Development of

Sustainable Ultra-High Strength Concretes

by

Ping Fang

A thesis submitted in conformity with the requirements

for the degree of Master of Applied Science

Department of Civil Engineering

University of Toronto

© Copyright by Ping Fang

2013

ii

Development of

Sustainable Ultra-High Strength Concretes

Ping Fang

Master of Applied Science

Department of Civil Engineering

University of Toronto

2013

Abstract

The influence of constituent materials and curing regimes on compressive strength

characterization of sustainable ultra-high strength concrete (SUHSC) was researched employing

a standard mortar mixer and a non-vibration consolidation method.

High intrinsic strength of fillers and reactive particles enhanced compressive strength. While the

effect of the type of silica fume was negligible, the increase of the content of silica fume

improved compressive strength. Use of combination of different sized limestone powders was

effective in modifying the particle size distributions of SUHSC. Water content of the mixtures

was an important parameter, but it was not the dominant influencing factor. An increase in the

content of cement did not necessarily lead to the improvement of compressive strength.

Elevated curing temperature, compared with ambient curing temperature, enhanced the

compressive strength, and there was no strength decline at later ages.

iii

Acknowledgments

I would first like to thank, from the bottom of my heart, my supervisor, Professor R. Doug

Hooton, for his kindness and patience. He is an outstanding supervisor who knows how to

stimulate the student’s potential for creativity and enthusiasm for research. His valuable insight

into the world of concrete helped situate this research in the company of the most cutting-edge

concrete technology. It was an honour to work with such a wonderful supervisor.

Many thanks must be given to Olga Perebatova. This research could not have been completed

without her excellent work in the lab.

I also must thank my classmates Eric Liu and Ardavan Amirchoupani, for their always friendly

help in my studies.

Finally, I must thank my mom and my husband. Without their support from the other side of the

globe, I would not have been able to finish this tremendous project.

iv

Table of Contents

Acknowledgements iii

Table of Contents iv

List of Tables vii

List of Figures x

List of Abbreviations xii

Chapter 1 Introduction 1

1.1 Background Information 1

1.2 Research Objectives 2

1.3 Scope of Research 2

Chapter 2 Literature Review 4

2.1 Theory of Strength for Cement Pastes 4

2.2 Particle Packing Model 5

2.2.1 Andreasen Model 5

2.2.2 Furnas Model 6

2.2.3 Modified Andreassen Model 6

2.2.4 Gap-graded Particle Size Distribution 9

2.2.5 F.de Larrard Model 9

2.3 Technique of Ultra-high Strength Cement Pastes 11

Chapter 3 Experimental Methodologies 16

3.1 Introduction 16

v

3.2 Materials 16

3.2.1 Constituent Materials 16

3.2.2 Properties of Constituent Materials 17

3.3 Mix Proportions Design 19

3.3.1 Phase I 19

3.3.2 Phase II 26

3.3.2.1 Mixture Design in Phase II 26

3.3.2.2. Particle Packing Model Employed 27

3.3.2.3 Calculation of Mixture Proportions 34

3.3.2.3.1 Cementitious Materials Contents 34

3.3.2.3.2. Limestone Powders Contents 35

3.3.2.4. Overview of Mixture Proportions of SUHSC in Phase II 38

3.3.3 Phase III 40

3.4 Mixing Methods 42

3.5 Curing Regimes 42

3.6 Test Methods 43

Chapter 4 Results and Discussions 44

4.1 Properties of Fresh Pastes 44

4.2 Compressive Strength Characterization in Phase I 49

4.2.1 Overview of Compressive Strength Characterizations in Phase I 49

4.2.2 Effect of Type of Fillers 51

vi

4.2.3 Effect of Content of Quartz Powder 52

4.2.4 Effect of Size of Sand 53

4.2.5 Effect of Type of Silica Fume 54

4.2.6 Effect of Slag and Metakaolin 55

4.3 Compressive Strength Characterization in Phase II 56

4.3.1 Overview of Compressive Strength Characterization in Phase II 56

4.3.2 Effect of Residual Packing Density β 59

4.3.3 Effect of Shrinkage Reducer Admixtures 62

4.3.4 Effect of Particle Size Distributions 63

4.4 Compressive Strength Characterization in Phase III 66

4.4.1 Optimization Constituent Proportions for Sustainability 66

4.4.2 Effect of Water to Binder Ratio in Phase III 69

4.4.3 Effect of Replacing Part of Slag by Limestone Powders 71

4.4.4 Effect of Size of Fine Limestone Powders 72

4.5 Effect of Curing Regimes 74

Chapter 5 Discussion 75

Chapter 6 Conclusions and Future Work 85

6.1 Conclusions 85

6.2 Recommendation for Future Work 87

Chapter 7 References 88

vii

List of Tables

Table 2.1 Residual Packing Density: Summary of Data 10

Table 2.2 Overview of Advancement of Ultra-high Strength Cement Concrete 11

Table 2.2-1 de Larrard’s UHSC 1994 12

Table 2.2-2 Typical RPC Compositions (by mass) and Properties 12

Table 2.2-3 UHPC Recommended by University of Michigan 13

Table 2.2-4. Typical Ductal® UHPC Compositions 13

Table 2.2-5 Typical Ductal® UHPC Performance 14

Table 2.3 Comparison of Mixture Proportion Parameters of Different UHPC 15

Table 3.1 Physical Properties of Constituent Materials 18

Table 3.2 Chemical Compositions of Constituent Materials 18

Table 3.3 Summary of Mixture Parameters in Phases I 20

Table 3.4 Design of Mixture Proportions Parameters 22

Table 3.5 Mixture Proportions Based on RPC 23

Table 3.6 Mixture Proportions on Effects of Maximum Size of Sand 24

Table 3.7 Mixture Proportions on Effects of ELKEN Silica Fume 24

Table 3.8 Mixture Proportions on Effects of W/P and Type of Silica Fume 25

Table 3.9 Mixture Proportions on Effects of Slag and Metakaolin 25

Table 3.10 Relative Ratio between Binder Ingredients 26

Table 3.11 Contents of Binder Ingredients in SUHSC 26

viii

Table 3.12 Constituent Proportions and Properties 28

Table 3.13-a Particle Packing Constitutes (1) 34

Table 3.13-b Particle Packing Constitutes (2) 34

Table 3.14 Optimization of Residual Packing Density β 36

Table 3.15 Designed Mixture Proportions 37

Table 3.16 Summary of Mixture Parameters in Phase II 38

Table 3.17 Mixture Proportions of Mixtures in Phase II 39

Table 3.18 Mixture Proportions on Optimization of Cement Contents in Phase III 40

Table 3.19 Mixture Proportions on Effect of Water to Binder Ratio in Phase III 41

Table 3.20 Mixture Proportions on Effects of LMP 12-PT Replacing Part of Slag 41

Table 3.21 Mixture Proportions on Effects of LMP 3-PT and LMP1-PT 41

Table 4.1 Effects of Dosages of SP on Workability 44

Table 4.2 Properties of SUHSC in Phase I 48

Table 4.3 Lowest Cement Content and Highest Compressive Strength in Phase I 50

Table 4.4 Mixture Proportion Parameters and Properties of Mixtures in Phase II 57

Table 4.5 Adjustment of Proportions of Different Particle Sizes Groups 63

Table 4.6 Properties of Optimal Constituent Proportions for Sustainability 67

Table 4.7 Effects of Water to Binder Ratio in Phase III 69

Table 4.8 Effects of LMP 12-PT Replacing Part of Slag 71

Table 4.9 Effects of LMP 3-PT and LMP1-PT 72

Table 5.1 Effect of Constituent Materials on Strength at Same W/C in Phase I 77

ix

Table 5.2 Effect of Constituent Materials on Strength at Same W/B in Phase I 78

Table 5.3 Effect of Constituent Materials at Same Water to Binder Ratio in Phase II 79

Table 5.4 Effect of Constituent Materials at Same Water to Cement Ratio in Phase II 80

Table 5.5 Effect of Constituent Materials at Same W/P in Phase II 81

x

List of Figures

Figure 2.1 Particle Size Distribution of Andreasen Model 8

Figure 3.1 Cumulative Distribution Curves of Constituent Materials 19

Figure 3.2 Simulated Particle Size Distributions of Mixtures with LMP 3-PT as

Cementitious Supplemental Materials in Phase I 30

Figure 3.3 Histogram Distributions of Constituent Materials 33

Figure 4.1 Effect of Mixing Time of SUHSC 45

Figure 4.2 Flowable and Cohesive Characterization of Fresh SUHSC 46

Figure 4.3 Overview of Compressive Strength in Phase I 50

Figure 4.4 Effects of Type of Fillers 51

Figure 4.5 Effects of Quartz Powder Content 52

Figure 4.6 Effects of Maximum Size of Sand 53

Figure 4.7 Effects of Type of Silica Fume 54

Figure 4.8 Effects of Slag and Metakaolin 55

Figure 4.9 Effects of W/B, W/C and W/P on Strength 58

Figure 4.10 Effects of Residual Packing Density β on Strength 60

Figure 4.11 Simulated Particle Size Distributions of Mixtures with Different β 61

Figure 4.12 Effects of Contents of Shrinkage Reducing Admixture 62

Figure 4.13 Simulated Particle Size Distributions of Mixtures with Blended Different

Particle Sizes of Limestone Powders 65

Figure 4.14 Effects of Cement Contenst in Phase III 68

xi

Figure 4.15 Effects of Water to Cement Ratio in Phase III 68

Figure 4.16 Effecsts of Water to Binder Ratio on Strength in Phase III 70

Figure 4.17 Effects of Part of Slag Supplemented by Limestone Powders on Strength 71

Figure 4.18 Effects of Particle Sizes of Fine Limestone Powders on Strength 73

Figure 4.19 Effects of Curing Regimes on Strength 74

Figure 5.1 Effects of W/B and W/C and W/P on Strength 83

Figure 5.2 Overview of Effect of Water to Binder Ratio on Strength 84

xii

List of Abbreviations

AD - Air-Detraining Admixture PS 1390

F- Fillers

GU – General Use (cement type)

LMP 12-PT - Limestone powder Betocarb®12-PT

LMP 6-PT- Limestone powder Betocarb®6-PT

LMP 3-PT - Limestone powder Betocarb®3-PT

LMP 1-PT - Limestone powder Betocarb®1-PT

MK – Metakaolin

NQS 160 - Natural quartz sand, finer than sieve 160µm

NQS 315 - Natural quartz sand, finer than sieve 315µm

NQS 1250 - Natural quartz sand, finer than sieve 1250µm

NQS 2000 - Natural quartz sand, finer than sieve 2000µm

NQS 5000 - Natural quartz sand, finer than sieve 5000µm

QZP - Quartz powder

SUHSC – Sustainable ultra-high strength concrete

SF – Silica fume

xiii

SL -Slag

SP - Polycarboxylate high range water reducer admixture

WRA - Water-Reducing Admixture

UHPC – Ultra-high performance concrete

UHSC – Ultra-high strength concrete

W - Water

W/P –Water to powder ratio, including all the powder particles

W/B – Water to binder ratio, including cement and supplemental cementitious materials

W/C – Water to cement ratio

- 1 -

Chapter 1 Introduction

1.1 Background Information

Efforts to discover higher strength concrete have not ceased since reinforced concrete structures

were first used in civil engineering in the early 1900’s. The concept of high strength concrete

evolved from compressive strengths more than 40MPa before 1980’s to higher than 130MPa

currently [1]. Cement pastes with compressive strengths of 509MPa and 318MPa were generated

by the hot-pressing technique and the room-temperature-pressing technique respectively in 1972

[2], Macro-Defect-Free cement (MDF cement) with compressive strengths of 300 MPa and

flexural strengths of 150 MPa were developed in 1980 [3]. In 1981, so-called DSP cement with

250MPa compressive strength was invented by filling the interstitial voids of cement particles

with silica fume [4]. Cement mortar with a compressive strength of 236 MPa was produced by

the optimization of particle packing in 1994 [5]. Reactive powder concrete (RPC) with

compressive strengths of between 200 MPa and 800 MPa was invented in 1995 [6]. Next came

innovations in ultra-high strength cement pastes, as cement pastes mixed in a defoaming mixer

achieved 30 MPa bending strength in 2010 [7]. With compressive strength exceeding 150 MPa

and with similar fabrication methods as conventional concrete, the self-consolidating ultra-high

performance concrete was first reported in 2011 [8, 9].

The most obvious advantage of ultra-high strength cement concrete is that it can allow the

components of concrete structures to have thinner sections and longer spans, such as RPC used

in bridge construction [10]. The castable feature and the lowest energy cost among popular

engineering materials [11] make ultra-high strength cement concrete suitable for use in

combination with other engineering materials. For example, MDF cement and DSP cement were

used to supplement steel in machine components and bulletproof materials [12]. Extremely low

- 2 -

porosity makes DSP cement concrete for use in vacuum container materials and one of the

candidate materials for Lunar-Base construction [12].

However, to achieve widespread application in civil engineering, the ultra-high strength cement

pastes must not only overcome obstacles which all innovational materials face, as summarized in

the literature [1]: “Structural Safety, Empirical knowledge base and Market Niche and Critical

Mass”, but also address the drawbacks of these new materials, such as the variations of

properties of MDF in wet environment.

1.2 Research Objectives

The research objective of this project is to investigate the influence of various factors on the

compressive strength of ultra-high strength concrete. The research will focus on the effects of the

constituent materials while the effects of curing regimes will also be investigated.

1.3 Scope of Research

The research was divided into three phases.

In Phase I, the constituent materials and their proportions were designed with reference to typical

RPC mixtures [6]. Commercially available limestone powder was employed as a main

constituent material to adjust the particle size distribution (DSP) of the mixture: LMP 3- PT

(average particle size 3µm) was used as the supplemental material for cement and LMP 12-PT

(average particle size 12µm) was used as supplemental material in place of quartz powder. The

effects of filler category and content, the maximum size of natural sand, the silica fume category,

the supplemental function of slag and metakaolin, as well as the variation of water to powder

ratio were investigated.

- 3 -

In Phase II, a design method of mixture proportioning for ultra-high strength concrete was

proposed which was the result of combination of Andreasen Particle Packing Model and the

Appolonian Particle Packing Model. The effects of the residual packing density β, particle size

distribution (PSD), and water to powder ratio, as well as binder content (the sum of cement, slag

and silica fume) were researched. A shrinkage reducing admixture (SRA) was creatively applied

to remove the large air voids entrapped in the fresh mixtures and to reduce the inner-cohesion of

powders.

In Phase III, a series of optimizations of mixture proportion were conducted by employing the

mixture proportion design method proposed in Phase II to achieve the feasible least cement

content and the highest compressive strength of the sustainable ultra-high strength concrete. The

effects of four different curing regimes were studied.

- 4 -

Chapter 2 Literature Review

2.1 Theory of Strength for Cement Pastes

Equation (2.1) is the Griffith strength equation [13] which reveals the strength mechanism of

brittle materials, such as hydraulic cement concrete:

R = C

E

2 (2.1)

Where R= failure stress, E=Young’s modulus, γ=surface energy, 2C= the length of a crack or

flaw.

For porous materials, such as hydraulic cement concrete, with particle materials surrounded by

paste, the particle sizes have the following relation with the strength [14]:

σp = (σ0 +K’d

-a)exp(-bP) (2.2)

Where σp = strength of the porous materials, σ0 and K’ are constants characteristic of the material,

P= percent porosity, d= particle diameter.

There is an empirical equation for the Young’s modulus (E) [14]:

E =Eg (1-εc) (2.3)

Where Eg = Young’s modulus of cement gel having zero capillary porosity, εc = capillary

porosity.

Abrams [15] and Feret [16] expressed the water to cement ratio is an important parameter to the

strength of concrete. Powers [17, 18] indicated pores and the fraction of cement hydrated are the

more important parameters to strength than the water to cement ratio. Young’s Modulus, surface

energy and toughness are affected by porosity [19]. The lower the porosity, the higher the

strength and Young’s modulus. The particle sizes of aggregates have relation with the strength of

- 5 -

porous materials. The bigger the particle size, the lower the strength will be. Flexural strength of

cement pastes is controlled by pore size distribution and the macroscopic voids which are

produced by entrained air or by poor particle packing. The micropores and the total porosity have

no relation with the flexural strength of cement pastes [20].

Considering all of the above, low porosity and small pore size are crucial in achieving high

strength cement concrete, and these parameters have been at the core of the development strategy

behind all the high strength or ultra-high strength cement concrete to date. For SUHSC, this

approach will be employed in the form of particle packing and extreme low water to powder

ratio.

2.2 Particle Packing Model

Among the many particle packing models, the Andreasen model [21] and Furnas [22] models

are considered to be “the two foundation models since 1900’s” [23]. The Andreasen model

concerns continuous particle size distribution (PSD) while the Furnas model deals with discrete

PSD. The Modified Andreasen model [24] and F.de Larrard’s model [25] are popularly applied

in concrete. In recent years, the Wet Packing Method was developed at Hong Kong University

[26] and the Statistical Method also was employed to optimize the PSD of cement pastes [27].

Following is a review of these current main particle packing models.

2.2.1 Andreasen Model

The Andreassen Model [21] is based on a continuous “feed” of “finer and finer” particle

materials to fill the smallest voids. The model is described in the following equation:

CPFT = q

D

d)( x100 (2.4)

Where CPFT is the Cumulative Percent Finer Than,

d is the particle size, µm,

D is the maximum particle size, µm,

- 6 -

q is the distribution coefficient between 0.333 (1/3) and 0.5 (1/2).

By computer simulation, 0% voids (i.e.100% packing) is possible if q is equal to or less than

0.37 [24].

2.2.2 Furnas Model

Compared with the particle packing of a continuous PSD used in the Andreasen model [21], the

Furnas model [22] is the particle packing for the discrete particle sizes. According to the Furnas

model, the best particle packing is that where the finer particles exactly fill the voids between the

larger particles, and at the same time, the voids between these finer particles are filled by the

further finer particles. This procedure can continuously be extended until the finest particle sizes

are obtained. This kind of monodispersions of particle is the feature of the discrete packing of the

Furnas model. The following equation describes the densest packed PSD of a continuous

distribution according to Furnas [28]:

SL

S

DD

DD

rr

rrCPFTloglog

loglog

100

(2.5)

where CPET is the cumulative percent finer than,

D is particle size, µm,

DS is the smallest particle size, µm,

DL is the largest particle size, µm,

r is the ratio of the volume of particles on one sieve to the volume on the next smaller sieve

2.2.3 Modified Andreassen Model

Based on reviewing and comparing the Andreasen Model (2.9) to the Furnas Model [22], Dinger

and Funk [24] presented a particle packing model-Modified Andreassen Model, which combines

the two models into the following single equation:

rf

S

rf

L

rf

S

rf

DD

DDCPFTloglog

loglog

100

(2.6)

Where CPFT is the cumulative percent finer than,

- 7 -

D is particle size,

DS is the smallest particle size,

DL is the largest particle size,

r is the ratio of the volume of particles on one sieve to the volume on the next smaller sieve,

f is 1/logCSR,

where CSR is the class size ratio representing the ratio of sizes of two adjacent size classes, equal

to 21/2

between two typically consecutive sieves.

Elkem Materials developed computer programs LISA and EMMA to design a PSD which could

be used in Self Consolidating Concrete (SCC), Very High Strength Concrete and even Ultra

High Strength Concrete based on either Andreasen model [21] or Modified Andreasen model [24]

[29].

The program LISA produces a graphic (Figure. 2.1) when the data (density, PSD and quantity) of

the components of the matrix are available. The red straight line represents the perfect PSD for

the matrix and the blue curve is the PSD being optimized. The optimization of PSD could be

obtained by adjusting the quantities of the components to make the blue curve closer to the red

line. The more closely the blue curve is to the red line, the better the PSD of the matrix will be.

However, because the red line is based on a continuous feed of finer and finer particles, while

normal powder mixtures have only a few components, a perfect correspondence between the

blue curve and the red line is therefore impossible.

- 8 -

a. PSD of Mix A1 by Andreasen Model

b. PSD of Mix A1 by Modified Andreasen Model

Figure 2.1 Particle Size Distribution of Andreasen Model

Particle Size Distribution

Andreassen: q=0.22gfedcb Particle Size Distributiongfedcb

Particle Size (Micron)

1 10 100 1000 10000

Perc

enta

ge P

ass (

Vol%

)

24.59

28.64

33.46

40.48

48.95

59.23

71.67

86.71

104.94

A1

Modified Andreassen: q=0.22gfedcb Particle Size Distributiongfedcb

Particle Size (Micron)

1 10 100 1000 10000

Perc

enta

ge P

ass (

Vol%

)

1.89

4.19

6.55

8.95

11.53

16.97

22.82

29.16

39.60

51.31

69.15

89.94

- 9 -

2.2.4 Gap-graded Particle Size Distribution

Gap-graded PSD is a popular particle packing design method used currently in China. A kind of

blended cement with only 25% clinker by mass achieved the same or higher early and late

strength properties of Portland cement by employing the gap-graded PSD method [30]. The gap-

graded PSD method was also employed in Micro--Defect-Free cement (MDF cement) [3] and

“High Early Strength Pozzolan Cement Blends” [27]. The obvious drawback of this particle

packing method is that it would cause large amounts of cement and SCMs which lack certain

size particles to become waste.

2.2.5 F.de Larrard Model

F.de.Larrard developed three generation particle packing models since the 1980’s. The first

generation model is the Linear Packing Density Model [31] which was used to obtain concrete

with higher than 80 MPa compressive strength at 28-day [32]. However, the silica fume content

in the optimized proportion was as high as 20%-30% by mass of cement [32]. The second

generation model is the Solid Suspension Model which was used to obtain a fluid mortar with

236 MPa compressive strength mortar at the water/binder ratio of 0.14 [32]. The drawbacks of

this ultra-high strength mortar are its large amounts of cement (1081kg/m3) and silica fume (334

Kg/m3), as well as its monodispersed sand component which led to wasting a large amount of

residual sands [32]. The third generation model is the Compressive Packing Model (CPM) which

is now popularly used. A feasible high performance concrete for pavement was achieved by

employing this model [33].

The Appolonian model is the case of CPM being used to determine the proportion of the mixture

which would obtain a maximum packing density. It assumes that “a sequence of diameters in

geometrical progression” [25] and one of them is dominant. If the particles were combined in the

following way, the highest virtual packing density would be obtained [25]:

Φ1 = β1

Φ2 = β2 (1-β1) (2.7)

Φn = βn (1-Φ1-Φ2- -Φn-1)

- 10 -

and the optimal value of virtual packing density is

γ = 1-

n

i 1

(1-βi) (2.8)

where Φn is the proportion (in volume) of the n fraction, related to the total volume of the

container, here d1 whose proportion is Φ1 is the dominant particle size. βn is the residual packing

density of a monodispersed fraction having a diameter equal to dn.

Reference values for the packing density are shown in Table 2.1 [25].

Table 2.1 Residual Packing Density: Summary of Data [25]

Cement Silica fume Limestone powder

Parameter Actual

packing

density Φ

Residual

packing

density β

Actual

packing

density Φ

Residual

packing

density β

Actual

packing

density Φ

Residual

packing

density β

Without SP 0.55-0.58 0.41-0.44 / / 0.57-0.62 0.47-0.57

With SP 0.60-0.68 0.45-0.50 0.49-0.63 0.55-0.64 0.61-0.65 0.52-0.58

For ternary constituents of particle sizes (d1>d2>d3), the wider the size span (d1/d3), the higher

the optimal packing density, and the higher the coarse material proportion will be [25].

de Larrard indicated that [25]: “with a given grading span (that is, d1 and d3 fixed, and d2

variable), it can be demonstrated that the intermediate diameter that leads to the highest virtual

packing density is the geometrical mean of the extreme diameters: that is, 31dd ” .

- 11 -

2.3 Technique of Ultra-high Strength Cement Pastes

Ultra-high strength cement pastes developed since 1970’s are summarized in Table 2.2 and de

Larrard’s packed UHSC, typical RPC and the latest UHPC models are shown in detail in Table

2.2-1 to Table 2.2-5, respectively.

Table 2.2 Overview of Advancement of Ultra-high Strength Cement Concrete

Name Rf. Compressive

strength

(MPa)

Cement

SF

SP W/P Porosity

(%)

Manufacture

methods

Roy’s

1972

2 650 100% 0 0 0.10 4.3 Pressure 350MPa,

250o C

MDF

1980

3 300 100% 0 / 0.12

︱

0.20

/ High shear

mixing, twin-roll

mill, particle size

distribution

controlled, 5MPa

pressure

DSP

1981

4 270 / / / 0.12

︱

0.22

/ Same as ordinary

cement pastes

Larrard’

s

1994

5 236 48%

1080.6

Kg/m3

15%

334.2

Kg/m3

1.3%C 0.14 / Mixed at variable

mixing speed,

Particle packing,

fluid mortar,

90o C hot water

curing 7 days

RPC

1995

6 200 37%

8%

1.6%

︱

1.9%

0.15

︱

0.19

/ Vibration, 90oC

hot water curing

UHPC

2011

8

9

194 35%

9%

0.5%P

︱

1.5%P

0.18

︱

0.22

/ Mixed at variable

mixing speed,

vibration

Note:

1. de Larrard’s mixtures have details in Table 2.2-1.

2. RPC mixtures have details in Table 2.2-2.

3. The cement content and SF content used in UHPC mixtures have details in Table 2.2-3.

4. The SP in solid content in SUHSC is 0.9% by mass of powder, P.

- 12 -

Table 2.2-1 de Larrard’s UHSC, 1994 [5]

Composition (kg/m3) Properties

Compressive strength (MPa)

With water curing With thermal curing

Sand 813.2 1 day 34.6 7 days 235.8

Cement 1080.6 7 days 120.6

Silica fume 334.2 28 days 164.9

Water 198.2 Tensile splitting strength

(MPa)

Air content 2% 28 days 6.6

Flow time 1 second Young’s modulus (GPa)

28 days 50.6

Table 2.2-2 Typical RPC Compositions (by mass) and Properties [6]

RPC 200 RPC800

Non fibered Fibered Silica

aggregates

Steel

aggregates

Portland Cement 1 1 1 1 1 1

Silica fume 0.25 0.23 0.23 0.23 0.23 0.23

Sand 150-600µm 1.1 1.1 1.1 1.1 0.5 /

Crushed quartz d50=10µm / 0.39 / 0.39 0.39 0.39

SP (Polyacrylate) 0.016 0.019 0.016 0.019 0.019 0.019

Steel fiber L=12mm / / 0.175 0.175 / /

Steel fiber L=3mm / / / / 0.63 0.63

Steel aggregates

<800µm

/ / / / / 1.49

Water 0.15 0.17 0.19 0.19 0.19 0.19

Compacting pressure / / / / 50MPa 50MPa

Heat treatment

temperature

20°C 90°C 20°C 90°C 250-400°C 250-400°C

Compressive strength 170-230 MPa 490-680MPa, quartz

sand

650-810MPa, steel

aggregates

Flexural strength 30-60 MPa 45-141 MPa

Fracture energy 20,000-40,000 J/m2

1,200-20,000 J/m2

Ultimate elongation 5,000x10-4

– 7,000 x10-6

m/m /

Young’s modulus 50-60GPa 65-75GPa

- 13 -

Table 2.2-3 UHPC Recommended by University of Michigan [8, 9]

Type UHPC UHPC1 UHPC2 UHPC3 UHPC4

Properties by mass

Cement PC

Type 1

1 1 1 1 1

Silica fume 0.25 0.25 0.25 0.25 0.25

Silica powder 0.25 0.30 0.30 0.25 0.25

Water 0.22 0.22 0.22 0.20 0.18

HRWR 0.0054 0.0072 0.0072 0.0072 0.0090

Fine sand1

(max 0.2mm)

0.28 0.50 0.00 0.28 0.27

Fine sand 2

(ma 0.8mm)

1.10 1.18 1.68 1.10 1.09

f’c (Prism) MPa,

28 day

192 175 171 190 163

f’c (Prism) MPa,

140 day

210 198 180 198 175

Spread value

mm

910 800 820 795 750

Table 2.2-4. Typical Ductal® UHPC Compositions [35]

Material Amount (kg/m3) Percent by Mass

Portland Cement 712 28.5

Fine Sand 1020 40.8

Silica Fume 231 9.3

Ground Quartz 211 8.4

Superplasticizer 30.7 1.2

Accelerator 30.0 1.2

Steel Fibers 156 6.2

Water 109 4.4

Note: vibration casting

- 14 -

Table 2.2-5 Typical Ductal® UHPC Performance [35]

Material Characteristic Range

Compressive Strength (MPa) 180-225

Modulus of Elasticity (GPa) 55-58.5

Flexural Strength (MPa) 40-50

Chloride Ion Diffusion (m2/s) 1.9x10

-14

Carbonation Penetration Depth (mm) < 0.5

Freeze-Thaw Resistance (RDF) 100%

Salt-Scaling Resistance (kg/m2) < 0.012

Entrapped Air Content 2–4%

Post-Cure Shrinkage (microstrain) 0

Creep Coefficient 0.2–0.5

Density (kg/m3) 2440–2550

Table 2.3 provides the analysis results of the constituent materials of the current UHPC

developed by other researchers, as summarized on the following:

1. High cement content, from 700 (kg/m3) to 1100 (kg/m

3);

2. Large silica fume content, from 200 (kg/m3) to 350 (kg/m

3), SF/C from 0.23 to 0.32;

3. Binder amounts varied from 900 (kg/m3) to 1100 (kg/m

3), the largest amount was as high

as 1415 (kg/m3);

4. All the UHPC had fine sand whose contents were between 800 (kg/m3) to 1250 (kg/m

3);

5. The material types of the powders were not confined, from ground quartz powder to

silica powder, or glass powder, etc. The amounts of powders were between 200 (kg/m3)

to 350 (kg/m3);

6. Low water content, less than 200 (kg/m3);

7. W/B varied between 0.12 (vibration casted) – 0.18;

8. W/C varied from 0.15 to 0.22

- 15 -

Table 2.3 Comparison of Mixture Proportion Parameters of Different UHPC

Lafarge

Ductal®

in 2006

University of Michigan

in 2011

Richard’s

in 1995

de

Larrard’s

in 1994

UHPC UHPC UHPC1 UHPC2 UHPC3 UHPC4 RPC UHPC

Reference [36] [8,9] [6] [5]

B(kg/m3) 943 1013 913 916 1028 1053 1039 1415

F(kg/m3) 1231 1321 1445 1451 1340 1356 1260 813

C(kg/m3) 712 810 730 733 822 842 845 1081

W(kg/m3) 109 178 161 161 164 152 177 198

SP(kg/m3) 30.7 0.54%C 0.72%C 0.72%C 0.72%C 0.90%C 19.7 -

SF(kg/m3) 231 203 183 183 206 211 194 334

Sand(kg/m3) Fine

sand

1020

Fine

sand

1118

Fine

sand

1226

Fine

sand

1231

Fine

sand

1134

Fine

sand

1145

930 813

Powder(kg/m3) Ground

quartz

211

Silica

powder

203

Silica

powder

219

Silica

powder

220

Silica

powder

206

Silica

powder

211

330 0

B/F 0.77 0.77 0.63 0.63 0.77 0.78 0.82 1.74

SF/C 0.32 0.25 0.25 0.25 0.25 0.25 0.23 0.31

W/B 0.12 0.18 0.18 0.18 0.16 0.14 0.17 0.14

W/C 0.15 0.22 0.22 0.22 0.20 0.18 0.21 0.18

fc (MPa) 180-

225

192 175 171 190 163 170-

230

236

Note: 1. B=binder, including cement and supplemental cementitious materials (SCM), i.e., silica

fume, slag, fly ash metakaolin;

2. F=fillers, including powders (except binders) and sand;

3. C=cement;

4. W=water;

5. Powder = B+F

- 16 -

Chapter 3 Experimental Methodologies

3.1 Introduction

The research involves three phases, Phase I focused on the effects of different constituent

materials on the compressive strength of ultra-high strength concrete. Phase II concentrated on

the proposed mixture proportion design method and overcoming problems which occurred in

mixing and casting procedures. Phase III focused on the optimization of mixture proportions in

order to approach the lowest cement content with the highest compressive strength.

3.2 Materials

3.2.1 Constituent Materials

Cement (GU): Holcim GU, Mississauga, Toronto, ON;

Silica fume (SF): S.K.W, Becancour, Quebec, Canada

Slag (SL): Holcim Slag, Mississauga, Toronto, ON;

Metakaolin (MK): Whitemud Resources, Saskatchewan

Limestone powder (LMP): Betocarb®12-PT* (LMP12-PT), Betocarb

®6-PT* (LMP6-PT),

Betocarb®3-PT* (LMP3-PT), Betocarb

®1-PT* (LMP1-PT), Omya Canada

*The designations refer to the average particle size of the limestone in microns

Quartz powder (QZP): Silex 325

Natural quartz sand (NQS): NQS 160—finer than sieve 160µm

NQS 315---finer than sieve 315µm

NQS 1250- natural sand, finer than sieve 1.25mm

NQS 2000--natural sand, finer than sieve 2.0mm

NQS 5000--natural sand, finer than sieve 5.0mm

- 17 -

Polycarboxylate high range water reducer admixture (SP): BASF GLENIUM 7700

Shrinkage-Reducing Admixture (SRA): MaterLIFE®SRA20, BASF Chemical company

Air-Detraining Admixture PS 1390 (AD): BASF Chemical Company

Water (W)—Tap water

3.2.2 Properties of Constituent Materials

The physical properties and chemical composition of the constituent materials are shown in

Table 3.1 and Table 3.2 respectively. The particle size distributions of the constituent powders

are plotted in Figure 3.1. The SKW SF had much bigger particle sizes than it should have (Figure

3.1). LMP 1-PT had a specific area of 7000 m2/kg, and the median diameter was 1.4 µm, its 60%

particles were smaller than 2 µm, and 40% particles were smaller than 1µm. The constituent

powders were divided into three groups according to their particle sizes in Figure 3.1. GU, QZP

and LMP 12-PT were in the group of coarse particles; LMP 6-PT, SL and SKW SF were in the

group of intermediate particles, and LMP 3-PT combined with LMP 1-PT were in the group of

fine particles.

The binders, also called cementitious materials, were composed of cement, silica fume and slag,

while the fillers were quartz powders, limestone powders and sands.

- 18 -

Table 3.1 Physical Properties of Constituent Materials

Density

(g/cm3)

Specific

Surface

Area

(m2/kg)

Average

Particle

Sizes

(µm)

Apparent

Bulk Density,

Loose

(1bs./ft3)

Apparent

Bulk Density,

Packed

(1bs./ft3)

GU 3.25 - - - -

SF 2.55 - - - -

LMP 1-PT 2.70 7000 1.4 28 59.5

3-PT 1125 3 37 69

6-PT 720 6 44 75

12-PT 380 12 50 87

SL 2.93 - - - -

QZP 2.65 - - - -

Table 3.2 Chemical Compositions of Constituent Materials

SiO2 Al2O3 Fe2O3 CaO MgO K2O SO3 LOI

GU 19.78 5.43 2.16 61.59 2.36 1.23 4.06 2.26

SF 99.7 0.29 0.01 0.01 - - 0.02 -

SL 37.41 9.01 1.21 35.75 12.42 0.37 2.89 0

LMP - - - 47.8 - - - 51.2

QZP 98.8 0.9 0.02 0.02 0.09 0.06 0.03 -

- 19 -

Fig.3.1 Cumulative Distribution Curves of Constituent Materials

3.3. Mix Proportions Designs

The mixture proportion design methods were different in each of the three Phases.

3.3.1 Phase I

In Phase I, the ultra-high strength concrete mixtures were designed according to the Reactive

Powder Concrete (RPC) mixture proportions. Quartz powder, Silex-325 was taken as a reference

filler, while LMP 12-PT and natural sand (NQS) (with maximum particle size from 160µm to

5mm) were used as fillers, separately or combined, as a substitute for the quartz powders. LMP

0

10

20

30

40

50

60

70

80

90

100

1 10 100

% P

assin

g

Microns (log)

Cumulative Distribution Analysis

Holcim Cement HE

Holcim Cement GU

Silex Quartz Powder

Lafarge SKW Silica Fume

Omya Limestone 3um

Omya Limestone 6um

Omya Limestone 12um

Holcim Slag - Mississauga

- 20 -

3-PT was used as the supplemental material of GU cement to reduce the cement content in

SUSHC. The mixture parameters were indicated in Table 3.3.

Table 3.3 Summary of Mixture Parameters in Phases I

Parameters Mixture ID Number of Tables

Aggregates QZP content A1-A4, A5-A8, A9-A12 Table 3.5

LMP 12-PT as aggregates supplement

of QZP

A13-A16 Table 3.5

LMP 12-PT combined with NQS 160

as aggregates

A17-A20 Table 3.5

The maximum size of sand A18 & A21-A24 Table 3.6

SF ELKEN supplement of SF SKW A25-A27, A21&A25, A28&A29 Table 3.7

Different water to powder ratio A21&A28, A25&A29 Table 3.8

SL and MK as SCM B1, B2, C1, C2, D1, D2 Table 3.9

In Table 3.4 and Table 3.5, the mixtures were divided into five groups, i.e., A1-A4, A5-A8, A9-

A12, A13-A16 and A17-A20. The difference between each group was the filler to binder ratio

and the type of the filler, while the varieties in every group were the cement content and its

replacement content LMP 3-PT (Table 3.4). Binders here were defined as the blend of cement

and silica fume, while the powders were the sum of all powder materials (cement, silica fume,

quartz powder, LMP 12-PT, and LMP 3-PT). The calculation of the material contents in Table

3.5 was according to the volume that each constituent material occupied. W/P and SP/P in Table

3.5 indicate the water to powder ratio and the superplasticizer (solid content) to powder ratio,

respectively. The water content in Table 3.5 includes the water content in SP whose water

content is 70%. The water content in W/P was the sum of water content in SP solution and the

water added during the mixing procedure.

Keeping the mixture proportions the same as in Table 3.5, the effects of different sizes of sand

were researched (Table 3.6). It should be pointed out that there were two kinds of powder

concepts in Table 3.6, i.e, the powder including sand is shown as P* and the powder excluding

sand is presented as P. The effect of cement content with different kinds of silica fume is shown

- 21 -

in Table 3.7. The effects of silica fume category and water content are shown in Table 3.8. Slag

and metakaolin employed as materials supplemental to cement are shown in Table 3.9.

- 22 -

Table 3.4 Design of Mixture Proportion Parameters

Mixtures Fine aggregates

/ binders

Different fine

aggregates

Cement

/binders

LMP 3-PT

/ binders

Silica fume/

binders

A1

0.63

Silex 325

(QZP)

0.90 0.00

0.10

A2 0.45 0.45

A3 0.35 0.55

A4 0.25 0.65

A5

0.73

0.90 0.00

A6 0.45 0.45

A7 0.35 0.55

A8 0.25 0.65

A9

0.83

0.90 0.00

A10 0.45 0.45

A11 0.35 0.55

A12 0.25 0.65

A13

0.73

LMP12-PT 0.90 0.00

A14 0.45 0.45

A15 0.35 0.55

A16 0.25 0.65

A17 0.50 sand

+

0.23 LMP 12-PT

Sand

(NQS 160)

+LMP 12-PT

0.90 0.00

A18 0.45 0.45

A19 0.35 0.55

A20 0.25 0.65

- 23 -

Table 3.5 Mixture Proportions Based on RPC (kg/m3)

ID NQS

160

QZP

LMP

12-PT

SF

SKW

GU LMP

3-PT

W/P W/B W/C W

SP

SP/P

(Solid)

(%)

A1 - 740 - 118 1060 0 0.17 0.28 0.31 330 60 0.9

A2 - 740 - 118 530 530 0.17 0.50 0.62 330 60 0.9

A3 - 740 - 118 412 648 0.17 0.62 0.79 330 60 0.9

A4 - 740 - 118 295 765 0.17 0.79 1.11 330 60 0.9

A5 - 806 - 110 994 0 0.17 0.29 0.33 330 60 0.9

A6 - 806 - 110 496 496 0.17 0.58 0.66 330 60 0.9

A7 - 806 - 110 386 608 0.17 0.66 0.84 330 60 0.9

A8 - 806 - 110 276 716 0.17 0.84 1.18 330 60 0.9

A9 - 862 - 104 936 0 0.17 0.31 0.35 330 60 0.9

A10 - 862 - 104 468 468 0.17 0.57 0.70 330 60 0.9

A11 - 862 - 104 364 572 0.17 0.70 0.90 330 60 0.9

A12 - 862 - 104 260 676 0.17 0.90 1.25 330 60 0.9

A13 - - 812 112 1000 0 0.17 0.29 0.36 330 60 0.9

A14 - - 812 112 500 500 0.17 0.53 0.72 330 60 0.9

A15 - - 812 112 390 610 0.17 0.65 0.84 330 60 0.9

A16 - - 812 112 278 722 0.17 0.84 1.17 330 60 0.9

A17 554 - 254 110 992 0 0.17*

0.30 0.33 330 60 1.3

A18 554 - 254 110 496 496 0.17* 0.54 0.66 330 60 1.3

A19 554 - 254 110 388 608 0.17* 0.65 0.84 330 60 1.3

A20 554 - 254 110 276 716 0.17* 0.84 1.18 330 60 1.3

Note: The contents of sand were included in the calculation of W/P of the mixture A17, A18,

A19 and A20. If the sand was expelled, the W/P of these mixtures was 0.24.

- 24 -

Table 3.6 Mixture Proportions on Effects of Maximum Size of Sand (kg/m3)

ID NQS LMP

12-PT

SF

SKW

GU LMP

3-PT

W/P

W/B W/C W

SP

SP/P

(Solid)

(%)

A18 160µm

554

254 110 496 496 0.17 0.54 0.67 330 60 1.3

A21 315µm

554

254 110 496 496 0.17 0.54 0.67 330 60 1.3

A22 1.25mm

554

254 110 496 496 0.17 0.54 0.67 330 60

1.3

A23 2.00mm

554

254 110 496 496 0.17 0.54 0.67 330 60

1.3

A24 5.00mm

554

254 110 496 496 0.17 0.54 0.67 330 60

1.3

Note: The contents of sand were included in the calculation of W/P of the mixtures. If the

sand is excluded, the W/P of these mixtures was 0.24.

Table 3.7 Mixture Proportions on Effects of ELKEM Silica Fume (kg/m3)

ID NQS

(315µm)

LMP

12-PT

SF

ELKEM

GU LMP

3-PT

W/P

W/B W/C W

SP

SP/P

(Solid)

(%)

A25 554 254 110 496 496 0.17 0.54 0.67 330 60 1.3

A26 554 254 110 388 608 0.17 0.66 0.85 330 60 1.3

A27 554 254 110 276 716 0.17 0.85 1.20 330 60 1.3

Note: The contents of sand were included in the calculation of W/P of the mixtures. If the

sand is excluded, the W/P of these mixtures was 0.24.

- 25 -

Table 3.8 Mixture Proportions on Effects of W/P and Type of Silica Fume (kg/m3)

ID NQS

(315µm)

LMP

12-PT

SF GU LMP

3-PT

W/P

W/B W/C W

SP

SP/P

(Solid)

(%)

A21 554 254 SKW

110

496 496 0.17 0.54 0.67 330 60 1.3

A25 554 254 ELKEM

110

496 496 0.17 0.54 0.67 330 60 1.3

A28 554 254 SKW

110

496 496 0.13 0.41 0.50 246 60 1.3

A29 554 254 ELKEM

110

496 496 0.13 0.41 0.50 246 60 1.3

Table 3.9 Mixture Proportions on Effects of Slag and Metakaolin (kg/m3)

ID NQS

(315µm)

LMP

12-PT

SF

SKW

GU LMP

3-PT

SL MK W/P W/B W/C W

SP

SP/P

(Solid)

(%)

B1 554 254 110 496 386 110 0 0.18 0.34 0.50 246 60 1.3

B2 554 254 110 386 496 110 0 0.18 0.34 0.64 246 60 1.3

C1 554 254 110 496 386 0 110 0.18 0.34 0.50 246 60 1.3

C2 554 254 110 386 496 0 110 0.18 0.34 0.64 246 60 1.3

D1 554 254 110 496 386 55 55 0.18 0.34 0.50 246 60 1.3

D2 554 254 110 386 496 55 55 0.18 0.34 0.64 246 60 1.3

- 26 -

3.3.2 Phase II

The objective of the research in Phase II is to maximize the compressive strength of Sustainable

Ultra High Strength Cement Pastes (SUHSC) with minimum porosity and at the lowest cement

content.

3.3.2.1 Mixture Design in Phase II

Three techniques reviewed in Chapter 2 were integrated to achieve the research objective. They

are the high strength-high performance cement pastes technique, the optimization of particle

packing technique, and the powder process technique.

Taking into account the sustainability and durability of ultra-high strength concrete, the

following ternary cementitious materials were employed as the binder materials, based on

literature results [36] (Table 3.10).

While fixing the relative ratio between the cementitious ingredients, the content of the binder

was changed to generate different compressive strength. The contents of the binders were 1000

kg/m3, 750 kg/m

3, 500 kg/m

3 and 250 kg/m

3 (Table3.11).

Table 3.10 Relative Ratio between Binder Ingredients

GU SL SF

1 0.3 0.1

Table 3.11 Contents of Binder Ingredients in SUHSC (kg/m3)

No. Binder GU SL SF

1 1000 714 214 72

2 750 536 160 54

3 500 357 107 36

4 250 179 53 18

- 27 -

The effect of water content was researched in Phase II. There should exist a critical water content

in extremely low water to cement ratio (or water to binder ratio) concrete, where water forms

into a thin film around the surface of the particles. When the water content is lower than that

critical value, there is not enough water to envelope the surface of particles, and the mixture will

still remain in the state of loose powders, even after extended period of mixing more than 20

minutes. When the water content is higher than the critical point, powder particles will be

suspended in the water film and the paste will behave normally.

3.3.2.2. Particle Packing Model Employed

The particle packing models reviewed in Section 2.2 are in fact all similar, because all of them

are based on the premise of obtaining the densest dry powder mixture. All of their approaches

are similar: using the finer particles to fill the voids of the coarser particles. A study [37] was

conducted to compare the values of the minimum porosity obtained from five different particle

packing models. The results showed that almost the same porosity value was obtained together

with the similar particle size distributions from these five kinds of particle packing models. The

Andreasen Model [21] and the Appolonian Model [25] were combined in order to design the

particle size distribution (PSD) of the ultra-high strength mixtures used in this project.

The Andreasen Model, is easy to operate with the computer program LISA. Take Figure 3.2 for

example. These are the simulation results of particle size distributions of the cement pastes in the

experiments performed in Phase I. The constituent proportions and the compressive strengths of

the mixtures are shown in Table 3.12. The simulation curves (the blue curve in Figure 3.2 A1

and A2) are close to the red curve, while the curves of mixtures A3 and A4 are far away from the

red curve, especially for mixture A4. These changes in curves have a good relation with

compressive strengths in Table 3.12. However, the major disadvantage of the LISA program is

that it is difficult to decide which parameter should be adjusted, particularly when there are more

than two mixture proportion parameters as candidates for adjustment.

- 28 -

Table 3.12 Constituent Proportions and Properties (m3/m

3)

ID

QZP

SF

GU

LMP 3-PT

Water

Compressive strength (MPa)

23°C water curing 3d 90°C

water curing 3d 28d

A1 0.279 0.046 0.326 - 0.33 86.0 116.8 124.4

A2 0.279 0.046 0.163 0.196 0.33 53.5 74.4 110.0

A3 0.279 0.046 0.127 0.240 0.33 39.9 70.2 94.8

A4 0.279 0.046 0.091 0.283 0.33 26.0 53.3 77.5

Considering the ideal structure model in very low porosity cementitious materials proposed in

reference [38], and taking the dominant grading concept from Appolonian Model [25], the

constituent particles in this project were divided into three groups according to their D50 values

(Table 3.13): coarse particles, intermediate particles and fine particles. The coarse particle

grading was employed as the dominant grading size. The powders in the same grading group also

have similar histogram distributions (Figure 3.3).

Two sets of particle packing constituents were designed (Table 3.13). The particle packing of

constituents in Table 3.13-1 forms the basis of the one in Table 3.13-2.

- 29 -

A1

Modified Andreassen: q=0.22gfedcb Particle Size Distributiongfedcb

Particle Size (Micron)

1 10 100 1000 10000

Perc

enta

ge P

ass (

Vol%

)

1.89

4.19

6.55

8.95

11.53

16.97

22.82

29.16

39.60

51.31

69.15

89.94

A2

Modified Andreassen: q=0.22gfedcb Particle Size Distributiongfedcb

Particle Size (Micron)

1 10 100 1000 10000

Perc

enta

ge P

ass (

Vol%

)

1.89

4.19

6.55

8.95

11.53

16.97

22.82

29.16

39.60

51.31

69.15

89.94

- 30 -

Fig.3.2 Simulated Particle Size Distributions of Mixtures with

LMP 3-PT as a Cementitious Supplemental Material in Phase I

A3

Modified Andreassen: q=0.22gfedcb Particle Size Distributiongfedcb

Particle Size (Micron)

1 10 100 1000 10000

Perc

enta

ge P

ass (

Vol%

)

1.89

4.19

6.55

8.95

11.53

16.97

22.82

29.16

39.60

51.31

69.15

89.94

A4

Modified Andreassen: q=0.22gfedcb Particle Size Distributiongfedcb

Particle Size (Micron)

1 10 100 1000 10000

Perc

enta

ge P

ass (

Vol%

)

1.89

4.19

6.55

8.95

11.53

16.97

22.82

29.16

39.60

51.31

69.15

89.94

- 31 -

Fig.3.3 (a) Coarse Particles

0

1

2

3

4

5

6

7

8

0

20

40

60

80

100

120

% T

ota

l V

olu

me

% P

assin

g

Microns

Holcim Cement GU

% of Total Volume

% Passing

0

1

2

3

4

5

6

7

8

0

20

40

60

80

100

120

% T

ota

l V

olu

me

% P

assin

g

Microns

Silex Quartz Powder

% of Total Volume

% Passing

0

2

4

6

8

10

0

20

40

60

80

100

120

% T

ota

l V

olu

me

% P

assin

g

Microns

Omya Limestone 12um

% of Total Volume% Passing

- 32 -

Fig.3.3 (b) Intermediate Particles

0

2

4

6

8

10

12

14

0

20

40

60

80

100

120

% T

ota

l V

olu

me

% P

assin

g

Microns

Omya Limestone 6um

% of Total Volume

% Passing

0

1

2

3

4

5

6

7

8

9

0

20

40

60

80

100

120

% T

ota

l V

olu

me

% P

assin

g

Microns

Holcim Slag - Mississauga

% of TotalVolume

0

1

2

3

4

5

6

7

8

0

20

40

60

80

100

120

% T

ota

l V

olu

me

% P

assin

g

Microns

LF SKW Silica Fume

% of TotalVolume

- 33 -

Fig.3.3 (c) Fine Particles

Fig.3.3 Histogram Distributions of Constituent Materials

The constituent materials in Table 3.13-1 were used in the Phase I experiments. Compared with

the constituent materials in Table 3.13-1, the difference in Table 3.13-2 is the use of the finer

limestone powder LMP 1-PT. Finer particles and wider grading spans are better for packing

density, according to comments in the literature [25]. Otherwise, the diameter d2 in all the

particle packing constituents (Table 3.13-1 to Table 3.13-2) is in the range of 31dd which is

assumed to lead to the highest packing density [25]. The values d1, d2 and d3 refer to the

diameters of the coarse grading group, intermediate grading group, and fine grading group

respectively.

According to Equation 2.7, the volume proportions of the coarse particles, intermediate particles,

and fine particles are calculated, respectively. The residual packing density β is taken from Table

2.1. For all of the particle gradings, β is fixed at the same value, that is, β1 =β2 =β3. For example,

if β1 is taken as 0.55 from Table 2.1,

Φ1 = β1 = 0.55 for coarse particles

Φ2 = β2 (1-β1) = 0.55 (1-0.55) = 0.25 for intermediate particles

Φ3 = β3 (1-Φ1-Φ2) = 0.55 (1-0.55-0.25) = 0.11 for fine particles

0

2

4

6

8

10

12

14

16

18

0

20

40

60

80

100

120

% T

ota

l V

olu

me

% P

assin

g

Microns

Omya Limestone 3um

% of Total Volume

% Passing

- 34 -

Table 3.13-a Particle Packing Constituents (1)

Size

(µm)

Coarse particles

D50=12µm

Intermediate particles

D50=6µm

Fine particles

D50=3µm

GU LMP 12-PT SF SL LMP 6-PT LMP 3-PT

D90 43 25 30 21 15 9

D50 12.5 10.5 5 7.5 4.3 2.6

D10 1.1 1.1 1.1 0.9 <0.9 <0.9

Table 3.13-b Particle Packing Constituents (2)

Size

(µm)

Coarse particles

D50=12µm

Intermediate particles

D50=6µm

Fine particles

D50=1µm

GU 12-PT SF SL LMP 6-PT LMP 1-PT

D90 43 25 30 21 15

D50 12.5 10.5 5 7.5 4.3

D10 1.1 1.1 1.1 0.9 <0.9

3.3.2.3 Calculation of Mixture Proportions

3.3.2.3.1 Cementitious Material Contents

The cementitious material contents in mass are calculated in Table 3.11. The following are the

contents calculated in volume, Vb.

Vb250 = 081.0007.0018.0056.02550

18

2930

54

3200

179

Vb500 = 162.0014.0036.0112.02550

36

2930

108

3200

357

Vb750 = 243.0021.0054.0168.02550

54

2930

162

3200

537

Vb1000 = 324.0028.0072.0224.02550

72

2930

216

3200

716

- 35 -

3.3.2.3.2. Limestone Powders Contents

Limestone powder contents were determined by combining the absolute volume method and the

Appolonian Model. Water to powder ratios were 0.16, 0.18, and 0.20. The volume of water is

involved in the calculation of the Appolonian Model, which is used for dry powder packing,

because the water is assumed to be only a thin film enveloping the particles in SUHSC pastes.

Air contents were assumed as 0. The following is an example of the calculation:

For the binder content at 1000 kg/m3 in Table 3.11 and the powder packing constituents listed in

Table 3.13-1, take W/P = 0.16 and β = 0.55 as an example,

55.0)1000

716(16.0

3200

716

2700

1212

WW

(3.1)

(16.02550

72

2930

216

2700

6 W

1000

722166 W) = 0.25 (3.2)

11.01000

16.02700

33 WW

(3.3)

where W12 , W6 and W3 are the mass (kg/m3) of LMP 12-PT, LMP 6-PT and LMP 3-PT,

respectively;

The solutions of Equations 3.1, 3.2 and 3.3 are:

W12 = 399 kg/m3

W6 = 192 kg/m3

W3 = 208 kg/m3

In this case, the virtual packing density γ is:

%100]1000

100020819239916.0324.0

2700

2081923991[1

=91.2% (3.4)

In order to explore the possibility of a denser packed SUHSC, the residual packing density β is

re-considered as follows:

- 36 -

Take β to replace 0.55 in Equation 3.1, β (1- β) to replace 0.25 in equation (3.2) and β[1- β-β(1-

β)] to replace 0.11 in Equation 3.3. Adding the two sides of Equations 3.1, 3.2 and 3.3 together

as follows:

)1000

716(16.0

3200

716

2700

1212

WW + (16.0

2550

72

2930

216

2700

6 W

1000

722166 W)

+ 1000

16.02700

33 WW =β +β (1- β) +β[1- β-β(1- β)] (3.5)

The left side of Equation 3.5 can then be written as follows:

1)1000

72216716(16.0

2550

72

2930

216

3200

716

2700

36123612

WWWWWW

So, Equation 3.5 would be changed to the following:

1=β +β(1- β) +β[1- β-β(1- β)] (3.6)

The equation (3.6) is presented as following equation:

133 23 (3.7)

The meaning of the solution β value in Equation 3.7 is that it could make the porosity be equal to

zero. For a special β from Equation 3.7, the relative contents of limestone powders in the zero

porosity cement pastes could be calculated by Equations 3.1to 3.3.

A series of data are put into Equation 3.7 to replace β to let the left side of the equation

approaches 1. The results are shown in Table 3.14. If one takes β at 0.55, 0.64 and 0.76 to

calculate the W12, W6 and W3, respectively, the results are shown in Table 3.15.

Table 3.14 Optimization of Residual Packing Density β

β 0.52 0.55 0.58 0.61 0.64 0.67 0.70 0.73 0.76

33 23 0.89 0.91 0.93 0.94 0.95 0.96 0.97 0.98 0.99

- 37 -

Table 3.15 Designed Mixture Proportions (kg/m3)

No. B

β W/P LMP

12-PT

GU LMP

6-PT

SL SF LMP

3-PT

W SP

1

1000

0.76

0.16 795

716

61

216

72

94 271 59

2 0.18 741 48 91 299 56

3 0.20 689 36 88 325 54

4

0.64

0.16 569 155 151 261 56

5 0.18 522 139 145 287 54

6 0.20 479 124 140 313 52

7

0.55

0.16 399 192 208 249 54

8 0.18 359 175 200 276 52

9 0.20 321 158 193 299 50

10

750

0.76

0.16 955

537

133

162

54

94 268 58

11 0.18 900 120 91 297 56

12 0.20 850 108 88 321 54

13

0.64

0.16 728 227 151 258 56

14 0.18 682 211 145 284 54

15 0.20 640 196 140 309 52

16

0.55

0.16 559 265 208 248 53

17 0.18 519 247 200 273 51

18 0.20 482 231 193 296 50

19

500

0.76

0.16 1115

357

202

108

36

94 266 57

20 0.18 1062 189 91 293 55

21 0.20 1012 177 88 318 53

22

0.64

0.16 889 296 151 255 55

23 0.18 844 280 145 281 53

24 0.20 801 265 140 305 51

25

0.55

0.16 719 177 208 223 48

26 0.18 680 316 200 269 51

27 0.20 643 300 193 293 49

28

250

0.76

0.16 1274

179

270

54

18

94 262 57

29 0.18 1222 258 91 290 54

30 0.20 1172 247 88 314 53

31

0.64

0.16 1047 364 151 252 54

32 0.18 1004 349 145 278 52

33 0.20 961 335 140 302 51

34

0.55

0.16 877 402 208 242 52

35 0.18 840 385 200 267 50

36 0.20 804 370 193 289 49

- 38 -

3.3.2.4. Overview of Mixture Proportions of SUHSC in Phase II

According to the mixture proportions given in Table 3.15, the parameters listed in Table 3.16

were investigated. The mixture proportions are shown in Table 3.17.

Table 3.16 Summary of Mixture Parameters in Phase II

Parameters Mixture numbers (see Table 3.17)

Water to powder ratio 4,5

Residual packing density β 15,18,19

Influence of shrinkage reducer admixture 6,7,8/11,12

Particle size distributions of SUHSC 1,2,3/ 12,13/ 20,21

Designed for high compressive strength 9,10,12,13,20,21

With less cement and a denser particle packing expected, the research on these parameters was

conducted with binder contents (B) of 500 kg/m3 and a residual packing density β at 0.64 in

Table 3.17. The β value was only kept at 0.64 in the mixtures No.1, No.14, No.15, No.16 and

No.17 in Table 3.17 because there were particle size distribution adjustments made for limestone

powders. However, the surprisingly low compressive strength of these mixtures required the B

value to be changed to 750 kg/m3 and even higher, to 1000 kg/m

3, as shown in Table 3.17. The

mixture with the highest compressive strength in Phase I (the mixture D1 in Table 3.9) was

employed as a reference mixture for the design of high compressive strength.

- 39 -

Table 3.17 Mixture Proportions of Mixtures in Phase II

No B β W/P Materials contents (kg/m3)

GU SL SF LMP

12-PT

LMP

6-PT

LMP

3-PT

LMP

1-PT

W SP SRA AD

1 500 0.64 0.21 360 108 36 844 296 150 0 312 56 20 24

2 500 / 0.21 360 108 36 0 680 610 0 312 56 20 24

3 500 / 0.21 360 108 36 0 880 410 0 312 56 20 24

4 500 / 0.20 360 108 36 0 880 396 0 312 56 6 4

5 500 / 0.18 360 108 36 0 880 396 0 268 56 6 4

6 500 / 0.17 360 108 36 0 880 396 0 256 56 12 8

7 500 / 0.17 360 108 36 0 880 396 0 250 56 18 4

8 500 / 0.17 360 108 36 0 880 396 0 244 56 24 4

9 716 / 0.15 496 110 110 808 0 386 0 226 60 18 4

10 756 / 0.18 496 150 110 0 0 546 608 270 90 18 4

11 1000 / 0.18 716 216 72 0 340 0 468 282 54 6 4

12 1000 / 0.18 716 216 72 0 340 0 468 278 54 12 4

13 1000 / 0.18 716 216 72 0 340 468 0 278 54 12 4

14 1000 0.64 0.18 716 216 72 522 140 146 0 282 54 6 4

15 750 0.64 0.18 538 161 54 682 210 150 0 280 54 6 4

16 500 0.64 0.18 360 108 36 844 280 146 0 276 54 12 4

17 250 0.64 0.18 180 54 18 1004 350 146 0 272 54 6 4

18 750 0.76 0.18 538 161 54 900 120 90 0 292 54 6+6 4

19 750 0.55 0.18 538 161 54 518 248 200 0 268 54 6 4

20 750 / 0.18 538 161 54 0 410 0 632 280 54 6 4

21 750 / 0.18 538 161 54 0 410 632 0 280 54 6 4

- 40 -

3.3.3 Phase III

Designing more sustainable mixtures was the major task in Phase III. The particle packing model

used was that employed in Phase II, i.e. combined Andreasen Model [21] and Appolonian Model

[25]. Fine sand with a maximum size of 315 µm was taken as the dominant constituent, cement

and slag together with silica fume were taken as the intermediate constituent, while LMP 1-PT

was used to adjust the particle packing to densify the particle packing.

To decrease the cement content, an optimization of the feasible cement amounts was studied

(Table 3.18). The water content was controlled to less than 200 kg/m3 and the water to binder

ratio was fixed at 0.20 in Table 3.18. The effect of water to binder ratio was varied in Table 3.19.

The effect of part of the SL replaced by LMP 12-PT was also studied (Table 3.20). The effect of

fine limestone powder is explored using the mix designs listed in Table 3.21.

Table 3.18 Mixture Proportions on Optimization of Cement Contents in Phase III

ID Constituent materials contents (kg/m3)

GU SL SF LMP

1-PT

NQS

315

W/P W/B W/C W SP SRA AD

1-20 600 300 100 0 1124 0.20 0.20 0.33 200 90 12 8

2-20 550 300 150 100 1124 0.18 0.20 0.36 200 90 12 8

3-20 500 300 200 200 1124 0.17 0.20 0.40 200 90 12 8

4-20 450 450 100 100 1124 0.18 0.20 0.44 200 90 12 8

5-20 400 450 150 200 1124 0.17 0.20 0.50 200 90 12 8

6-20 350 450 200 0 1124 0.20 0.20 0.57 200 90 12 8

7-20 300 600 100 200 1124 0.17 0.20 0.67 200 90 12 8

8-20 250 600 150 0 1124 0.20 0.20 0.80 200 90 12 8

9-20 200 600 200 100 1124 0.18 0.20 1.00 200 90 12 8

- 41 -

Table 3.19 Mixture Proportions on Effect of Water to Binder Ratio in Phase III

ID

Constituent material contents (kg/m3)

GU SL SF LMP

1-PT

LMP

3-PT

NQS

315

W/P W/B W/C W SP SRA AD

6-16-1 350 450 100 100 0 1124 0.15 0.16 0.46 160 60 12 8

6-18-1 350 450 100 100 0 1124 0.16 0.18 0.51 180 60 12 8

6-20-1 350 450 100 100 0 1124 0.18 0.20 0.57 200 60 12 8

Table 3.20 Mixture Proportions on Effects of LMP 12-PT Replacing Part of Slag

ID

Constituent material contents (kg/m3)

GU SL LMP

12-PT

SF LMP

1-PT

NQS

315

W/P W/B W/C W SP SRA AD

6-16-1 350 450 0 100 100 1124 0.15 0.16 0.46 160 60 12 8

6-16-1-25 350 338 112 100 100 1124 0.15 0.16 0.46 160 60 12 8

6-16-1-50 350 226 226 100 100 1124 0.15 0.16 0.46 160 60 12 8

5-16-1-75 350 112 169 100 100 1124 0.15 0.16 0.46 160 60 12 8

Table 3.21 Mixture Proportions on Effects of LMP 3-PT and LMP1-PT

ID

Constituent material contents (kg/m3)

GU SL SF LMP

1-PT

LMP

3-PT

NQS

315

W/P W/B W/C W SP SRA AD

6-18 350 450 200 0 0 1124 0.18 0.18 0.51 180 60 12 8

6-18-1 350 450 100 100 0 1124 0.18 0.20 0.51 180 60 12 8

6-18-3 350 450 100 0 100 1124 0.18 0.20 0.51 180 60 12 8

6-18-1-3 350 450 100 50 50 1124 0.18 0.20 0.51 180 60 12 8

- 42 -

3.4. Mixing Methods

The following is the mixing schedule used for producing ultra-high strength concrete.

Step 1: Blend all the powders (including fine sand);

Step 2: Add all the chemical admixtures into the water in the mixer bowl;

Step 3: Pour the mixed powders into the mixer bowl;

Step 4: Mix the mixture until it becomes a fluid paste.

3.5. Curing Regimens

In Phase I and Phase II, the mixtures were self-consolidated into moulds and covered with plastic

films at 23 ºC and 90%R.H. The demolding time was approximately 24 h after casting. However,

for the mixture with high SP content, such as the No.10 mixture in Table 3.17 (where SP content

was 90 kg/m3, exceeding that of the regular mixture by 50%), the setting time was prolonged and

resulted in the demolding time being delayed. After demolding, the samples were put into two

kinds of curing regimes. One was cured in 23 ºC water, with test ages of 3 days and 28 days,

respectively. Another one was cured in 90 ºC hot water and tested after 3 days.

In Phase III, all of the mixtures were demolded on the third day after casting, and then cured

under the same regimes as in Phase I and in Phase II above, except for mixture 6-18-1 which was

used to investigate the effect of different curing regimes on the compressive strength. There were

three different accelerated curing temperatures, i.e., 75°C, 85°C and 95°C. Under each

temperature, samples were cured under elevated temperatures for different time periods, i.e., 2

days, 3 days and 4 days. While half of the samples were tested for compressive strength at the

ages of 2d, 3d and 4d, respectively, the other half of the samples were cured at 23 °C and 50%

RH environment until the 28th day, and then their compressive strength was measured.

- 43 -

3.6 Test Methods

There were three parameters tested for each fresh mixture: wetting time, paste time, mixing time.

The wetting time is the moment when there are small paste balls forming and their surface

becomes moist. The paste time is the moment when the moist balls connect together to be a

single paste mass. The mixing time is the moment when the paste can self-flow.

Compressive strength tests were conducted according to ASTM C 109/C 109M – 07 Standard

Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50-mm]

Cube Specimens).

- 44 -

Chapter 4 Experimental Results

4.1 Properties of Fresh Pastes

There are three significant features for the fresh ultra-high strength concrete in the project. The

first characteristic is the very high dosage of SP (60 kg per cubic meter of concrete) and long

mixing time (longer than 8-10 minutes). The mixing procedure is shown in Figure 4.1. There

may be different times required for different mixture constituents and proportions to achieve the

same situation as shown in Figure 4.1, but the procedure is the same.

The effects of the dosage of SP on the workability of the ultra-high strength concrete are shown

in Table 4.1. The dosage of SP in the project was mainly fixed at 60 kg/m3 throughout the

research. The wetting time means that there are small surface-wetted particles appearing, as in

Figure 4.1 at 3 minutes. The paste time refers to the bulk cement pastes forming, as in Figure 4.1

at 7 minutes. The values of the wetting time and the paste time are not precise, but the variation

was always between 1 to 2 minutes.

Table 4.1 Effects of Dosages of SP on Workability

ID SP

(kg/m3)

Wetting

Time (min)

Paste Time

(min)

Flow Notes

1 70 1.25 3.39 128 10 min become fluid

2 60 2.40 4.50 116 10 min can flow slowly, 15 min become

fluid

3 50 3.30 8.40 86 20 min become fluid, 33 min remains

fluid

4 40 11.0 14.0 / did not- flow

The second feature is that the pastes were fluid and cohesive, as shown in Figure 4.2. The third

feature is that large amounts of air bubbles were entrapped during the mixing process if there

was no shrinkage reducing admixture added. These air bubbles could not be expelled by either

vibration or vacuum, due to the viscous nature of the mixture.

- 45 -

0.47 min dry mortar balls appear 2.47 min dry mortar balls

3.00 min small mortar loose balls appear wet 4.00 min wet mortar balls get bigger

5 min 6 min

7.00 min 8 min starts to flow

9.00 min can flow 10.00 min mixing stopped

Figure 4.1 Effect of Mixing Time of SUHSC

- 46 -

(a) Flow without vibration (b) Self-consolidation

Figure 4.2 Flowable and Cohesive Characterization of Fresh SUHSC

These features of the fresh ultra-high strength concrete could be understood through the powder

techniques. Cement pastes with extreme low water to powder ratio have different inter-particle

relationships compared to ordinary cement pastes. When a small amount of water is mixed with a

large number of fine particle powders, water will wet the surface of the powders and form small

wetting particles, as shown in Figure 4.1 at 3 minutes, which is called wetting and nucleation in

the literature [34]. The wetting particles grow continuously to form a dough at 10 minutes in

Figure 4.1 and this is called consolidation and coalescence in the literature [34].

In the dough of the fresh UHSC, water forms into a film surrounding the particles, and the

neighboring particles become connected to each other through this water film. As the water

content increases, the water film becomes thicker, until the water bridge between the two

particles is filled in and the particles start to become suspended in liquid water, just as in normal

cement pastes.

The radii of the curvature of the surface of the water bridge between the two powder particles are

influenced by the surface tension of the aqueous water bridge [34]. The smaller the surface

tension, the smaller the curvature of the surface of the aqueous water bridge, and the lower the

inner-cohesion of powders. As an effective material in reducing the surface tension of the

aqueous water in concrete, a shrinkage-reducing admixture should be a potential candidate

material for the reduction of the inner-cohesion of powders, and this assumption was proven in

the experiments in Phase II. Therefore, all the mixtures in Phase II and Phase III used Shrinkage

- 47 -

Reducing Admixture (SRA) accompanied by Air-Detraining admixture (AD) as essential

constituents, which made the entrapped air voids disappear and the mixture more easily placed;

furthermore, additional workable time was enabled by the function of SRA, which delayed the

setting time of SUHSC .

Table 4.2 provides the results of the properties of ultra-high strength concrete tested in Phase I.

The mixing time is about three times that of conventional cement mortar and the paste has

obvious thixotropy and strong inner-cohesion. Limestone powders can decrease the inner-

cohesion and entrapped air contents compared with the conventional mixtures (mixtures A1, A5,

A9, and A13 in Table 4.2).

Water to powder ratio has an obvious influence on the mixing process. It was discovered through

a set of mixtures (A17 to A27 in Table 4.2) where the water to powder ratio was initially

calculated incorrectly. These mixtures had similar mixing times and entrapped air contents as

conventional cement mortars when the sand was taken as part of the powders to calculate the

water to powder ratio which was fixed at 0.17 as shown in Tables 3.5, 3.6 and 3.7. In reality, the

water to powder ratio (the content of sand not included) was 0.24 in these mixtures. For those

mixtures (A28, A29 and B1, B2, C1, C2, D1, D2 in Table 3.8 & 3.9) for which the water to

powder ratio was really 0.18, the mixing time and the entrapped air contents increased (Table

4.2).

In Phase I, there was no effective method to reduce the entrapped air contents in the mixtures,

although a vibration process and a vacuum process, as well as the combination of both, were

employed. However, if the mixture was cast in a shape of a thin belt, the entrapped air bubbles

could be expelled effectively as shown by the decreased air contents of A8 and A11 in Table 4.2.

BASF PS 1390 Air-Detraining Admixture for Non air-Entrained Concrete did not work here.

Vacuum mixing method may be tried as suggested in one report [7].

The SUSHC in the experiments was sensitive to the chemical ingredients and dosage of the

superplasticizer (SP). While EUCON 37 did not work, BASF Master Builders GLENIUM 7700

- 48 -

showed good behaviour. The SP dosage was fixed at 60 kg/m3 (the solid content was 18 kg/m

3)

in this project.

Table 4.2 Properties of SUHSC in Phase I

ID Wetting

time

(min)

Paste

time

(min)

Mixing

time

(min)

Air

Content

(%)

Compressive strength (MPa)

23°C water curing 3d 90°C

water curing 3d 28d

A1 5.0 6.0 8.5 5.1 86.0 116.8 124.4

A2 5.5 6.0 8.0 4.3 53.5 74.4 110.0

A3 6.0 7.0 8.0 4.3 39.9 70.2 94.8

A4 6.0 6.5 8.5 4.8 26.0 53.3 77.5

A5 5.0 6.0 8.5 4.5 82.4 100.3 108.9

A6 4.5 5.5 8.5 4.5 44.9 80.8 99.1

A7 6.0 7.0 8.5 4.0 35.3 62.3 111.6

A8 5.5 6.5 8.0 3.5*

20.7 50.9 72.9

A9 4.5 5.5 8.0 5.6 70.4 103.6 123.4

A10 4.5 5.0 8.0 4.5 41.7 73.5 106.9

A11 5.0 5.5 8.0 3.1*

30.8 61.5 87.3

A12 5.0 5.5 8.0 4.1 19.5 43.5 85.6

A13 5.0 6.0 12.0 5.4 83.1 107.3 105.5

A14 4.0 5.0 8.0 3.3 52.0 88.4 94.1

A15 4.5 5.0 8.0 3.5 39.3 68.0 89.2

A16 4.5 4.5 8.0 2.9 23.9 60.1 61.1

A17 1.5 2.0 4.5 1.4

79.7 111.6 112.3

A18 1.5 1.5 3.0 1.8

46.9 75.2 93.1

A19 1.0 1.0 3.0 1.5

34.9 60.2 79.9

A20 1.0 1.0 3.0 1.0

20.3 50.4 63.2

A21 1.0 1.5 2.5 1.9 36.1 75.9 85.7

A22 1.0 1.0 2.5 1.9 40.1 80.9 87.3

A23 1.0 1.0 2.0 2.6 41.1 83.1 85.6

A24 0.5 0.5 2.0 1.9 37.5 50.1 83.9

A25 1.0 1.5 2.5 2.1 40.1 89.1 94.1

A26 1.0 1.5 2.5 2.6 26.3 67.7 76.3

A27 1.0 1.5 2.5 3.4 14.1 48.9 66.7

A28 6.0 7.0 9.5 2.7 55.1 111.5 122.7

A29 6.0 7.0 10.0 3.7 55.6 112.0 111.7

B1 6.5 7.5 10.0 4.1 61.5 102.1 120.4

B2 6.0 7.0 9.5 3.8 49.1 109.9 96.4

C1 8.5 9.5 16.0 4.8 67.5 96.7 107.7

C2 13.0 15.0 20.0 4.4 65.2 94.3 112.3

D1 7.5 8.5 12.5 3.6 66.3 123.6 125.1

D2 9.0 10.0 13.5 4.1 60.1 111.1 112.4

- 49 -

4.2 Compressive Strength Characterization in Phase I

4.2.1 Overview of Compressive Strength Characterization in Phase I

The respective compressive strength of 35 mixtures with two kinds of curing regimes at three

different ages is shown in Figure 4.3 and Table 4.2. There were large voids in almost all of the

samples, but less so in samples with the water to powder ratio at 0.24 (samples A17 to A27 in

Table 4.2). The white colour cores in the high strength samples had unusual appearances,

different from conventional cement concrete. It might be presumed that there were the same

failure patterns for SUHSC as with conventional high strength concrete, whose failures always

occur in aggregates or in the interfacial between aggregates and cementitious materials.

The highest compressive strength was achieved by the mixture D1 ( Table 4.2 &4.3), whose

cement content was substituted 50% by the blended powders: LMP 3-PT, SL and MK, while its

fillers were combined with equal masses of NQS 315μm and LMP 12-PT, with the curing regime

under 90 °C hot water for 3 days. On the other hand, the lowest compressive strength was

performed by the mixture A12 (Table 4.2), whose cement content was substituted 75% by LMP

3-PT, while LMP 12-PT was used as fillers, with 23 °C water curing for 28 days. The lowest

cement content with high strength was obtained by the mixture A4 (Tables 4.2 & 4.3). The

strength properties could be better if all of the entrapped air could be expelled.

Figure 4.3 provides information that the compressive strength of all mixtures cured in 90° C

water for 3d were close to, and most of them were higher than, those of the mixtures cured by

23°C water curing for 28d. Therefore, the compressive strength cured under 90° C water for 3d

was taken as the index to evaluate the compressive strength characterization of SUHSC in this

project.

- 50 -

Table 4.3 Lowest Cement Content and Highest Compressive Strength in Phase I

ID Constituent Materials (kg/m3) Compressive strength (MPa)

NQS

315

QZP LMP

12-PT

SF GU

LMP

3-PT

SL MK

28d 23°C

water curing

3d 90°C

Water curing

A4 - 740 - 118 295 765 - - 53.3 77.5

D1 554 - 254 110 496 386 55 55 123.6 125.1

.

Figure 4.3 Overview of Compressive Strength in Phase I

0

20

40

60

80

100

120

140

A1 A3 A5 A7 A9 A11 A13 A15 A17 A19 A21 A23 A25 A27 A29 B2 C2 D2

Co

mp

ress

ive

str

en

gth

(M

Pa)

Mixture ID

Overview of Compressive Strength

3d 23°C water

28d 23°C water

3d 90°C water

- 51 -

4.2.2 Effect of Type of Fillers

Figure 4.4 indicates the effect of type of filler on the compressive strength. There was little effect

on the conventional SUHSC (A5, A13 and A17), while the mixtures with cement partly replaced

by limestone powder LMP 3-PT were influenced by the type of filler used (the group of A6, A14

and A18; the group of A7, A15 and A19, and the group of A8, A16 and A20). Under the curing

condition of 90° C water for 3d, the mixtures with quartz powder QZP as fillers had higher

compressive strength than those with LMP12-PT as fillers, because of the reaction between the

quartz powders and cement pastes under heat [8]. However, the situation was reversed for the

mixtures cured in 23°C water, either for 3d or for 28d. The mixtures with LMP12-PT as fillers

had higher compressive strength than those with QZP as fillers. NQS 160 as part of fillers had no

obvious effect on the compressive strength, neither at ambient temperature nor at elevated

temperature. The same effect for the quartz aggregates and the limestone aggregates are in the

research of the literature [39].

Figure 4.4 Effects of Type of Fillers

0

20

40

60

80

100

120

Sile

x

12

PT

San

d-1

2P

T

Sile

x

12

PT

San

d-1

2P

T

Sile

x

12

PT

San

d-1

2P

T

Sile

x

12

PT

San

d-1

2P

T

A5 A13 A17 A6 A14 A18 A7 A15 A19 A8 A16 A20

Co

mp

ress

ive

str

en

gth

(M

Pa)

Different Fillers and Mixtures ID

Comparison of Different Fillers

3d 23°C water curing 28d 23°C water curing 3d 90°C water curing

- 52 -

4.2.3 Effect of Content of Quartz Powder

The effect of the content of QZP is shown in Figure 4.5. There were no obvious influence for the

mixtures where cement was replaced by LMP 3-PT (a group of A2, A6, A10, a group of A3, A7,

A11 and A4, A8, A12), but there was some effect on conventional mixtures (A1,A5,A9).

Figure 4.5 Effects of Quartz Powder Content

0

20

40

60

80

100

120

140

0.63B0.73B0.83B 0.63B0.73B0.83B 0.63B0.73B0.83B 0.63B0.73B0.83B

A1 A5 A9 A2 A6 A10 A3 A7 A11 A4 A8 A12

Co

mp

ress

ive

str

en

gth

(M

Pa)

Quartz powder Silex contents and Mixtures ID

Effect of contents of Quartz Powder

3d 23°C water curing 28d 23°C water curing 3d 90°C water curing

- 53 -

4.2.4 Effect of Size of Sand

The maximum size of sand had no obvious influence on the compressive strength when the

mixtures were 90° C water cured for 3d, as shown in Figure 4.6. However, the compressive

strength of the mixtures with the maximum size of sand 5.00 mm dropped steeply under 23° C

water curing for 28d. Actually, the sand in the mixtures in Phase I only scattered in the cement

pastes due to its small amount.

Figure 4.6 Effects of Maximum Size of Sand on Strength

0

10

20

30

40

50

60

70

80

90

100

160µm 315µm 1.25mm 2.00mm 5.00mm

A18 A21 A22 A23 A24

Co

mp

ress

ive

str

en

gth

(M

Pa)

Maximum Sizes of Sand and Mixture ID

Effect of Maximum Size of Sand

3d 23°C water curing 28d 23°C water curing 3d 90°C water curing

- 54 -

4.2.5 Effect of Type of Silica Fume

The compressive strength of the mixtures with ELKEM silica fume is a little higher than that

with SKW silica fume when the mixtures had higher water to powder ratio (W/P 0.17), while

both kinds of silica fume have had the same effect on the compressive strength when the

mixtures had lower water to powder ratio (W/P 0.13), as shown in Figure 4.7. Some literature [8]

suggests that the influence of the type of silica fume on the compressive strength of ultra-high

strength concrete is “negligible.

Figure 4.7 Effects of Type of Silica Fume on Strength

0

20

40

60

80

100

120

140

SKW-W/P0.17

ELKEN-W/P0.17

SKW-W/P0.13

ELKEN-W/P0.13

A21 A25 A28 A29

Co

mp

ress

ive

str

en

gth

(M

Pa)

Type of silica fume and mixture ID

Effect of type of silica fume 3d 23°C water curing 28d 23°C water curing

- 55 -

4.2.6 Effect of Slag and Metakaolin

SL and MK were used to supplement the cement and LMP 3-PT respectively (Table 3.9) and the

compressive strength of the mixtures is shown in Figure 4.8. While there was no influence on

compressive strength of the mixtures C1 and C2, when the MK was added at 10% content of

powders (including SF, GU, LMP 3-PT and SL, as well as MK), the compressive strength of the

mixtures supplemented by SL (B1 and B2) decreased as the cement content dropped when 90° C

water cured for 3d, except for the compressive strength of mixture cured for 28d in 23° C water.

The compressive strength of the mixtures supplemented by a combination of SL and MK was

higher than of those with either SL or MK alone, especially when 23° C water cured for 28d (the

group of B1, C1 and D1, as well as B2, C2 and D2).

Figure 4.8 Effects of Slag and Metakaolin on Strength

0

20

40

60

80

100120

140

GU 0.45SL0.10

GU0.35SL 0.10

GU 0.45MK0.10

GU 0.35MK 0.10

GU 0.45SL 0.05

MK 0.05

GU 0.35SL 0.05

MK 0.05

Co

mp

ress

ive

str

en

gth

(M

Pa)

Proportions of binders

Effects of Slag and Metakaolin 3d 23°C water curing 28d 23°C water curing 3d 90°C water curing

- 56 -

4.3 Compressive Strength Characterization in Phase II

4.3.1 Overview of Compressive Strength Characterization in Phase II

The compressive strength of the mixtures in Phase II shown in Table 4.4 turned out to be much

lower than was expected. To analyze the reasons for the disappointing compressive strength, the

experimental data of Reactive Powder Concrete (RPC) in 1995 [6], Ductal® High Performance

Concrete in 2006 [35], de Larrard’s Ultra-high Strength Concrete in 1994 [5], and the UHPC of

university of Michigan in 2011 & 2012 [8, 9] were studied. The results of were summarized in

Table 2.3.

It was found from Table 2.3 that water to binder ratio (W/B) was still a key factor influencing the

compressive strength of ultra-high strength concrete. The lower the W/B, the higher the

compressive strength will be. The W/B is in the range of 0.12 to 0.18 for all of the UHPC with

compressive strength higher than 150 MPa (Table 2.3). The positive relation between W/B and

compressive strength of SUHSC are shown in Figure 4.9 a. The same trends between W/C and

compressive strength are also shown in Figure 4.9 b, while W/P has no regular relation with the

compressive strength, as exhibited in Figure 4.9 c.

- 57 -

Table 4.4 Mixture Proportion Parameters and Properties of Mixtures in Phase II

Note:

1. B=Binders, including cement GU, slag and silica fume SKW;

2. F=Fillers, including all different particle size limestone powders, i.e, Betocarb® 12-PT, 6-PT,

3-PT and 1-PT;

3. P=Powders, including binders and fillers;

4. W =Water, not including the water in the admixtures of SP, SRA and AD

Mix B F B/F β W/C W/B W/P Wetting

Time

(min)

Pasting

Time

(min)

Mixing

Time

(min)

Density

(kg/m3)

fc

3d

85°C

Water

curing

(MPa)

1 500 1290 0.39 0.64 1.06 0.76 0.21 0.5 1.0 3.0 2101 42.0

2 500 1290 0.39 0.64 1.06 0.76 0.21 0.5 1.0 3.0 2020 45.3

3 500 1290 0.39 0.64 1.06 0.76 0.21 0.5 1.0 3.0 2105 48.2

4 500 1276 0.39 0.64 0.99 0.72 0.20 1.0 2.0 3.0 2152 56.9

5 500 1276 0.39 0.64 0.87 0.63 0.18 2.0 5.5 10.0 2251 64.9

6 500 1276 0.39 0.64 0.86 0.62 0.17 2.0 4.0 11.0 2301 67.0

7 500 1276 0.39 0.64 0.85 0.61 0.17 2.5 4.0 12.0 2248 59.0

8 500 1276 0.39 0.64 0.84 0.61 0.17 2.0 3.0 12.0 2203 57.0

9 716 1194 0.60 0.64 0.57 0.40 0.15 2.5 11.0 22.0 2251 92.0

10 756 1154 0.66 0.64 0.70 0.46 0.18 3.0 4.0 6.0 2237 79.0

11 1000 808 1.24 0.64 0.46 0.33 0.18 3.0 3.5 7.0 2285 85.0

12 1000 808 1.24 0.64 0.46 0.33 0.18 2.0 3.0 Did not

flow

2299 87.0

13 1000 808 1.24 0.64 0.46 0.33 0.18 3.0 4.0 7.0 2392 90.5

14 1000 808 1.24 0.64 0.46 0.33 0.18 2.5 3.5 10.0 2347 107.0

15 750 1042 0.72 0.64 0.60 0.43 0.18 2.0 3.5 10.0 2296 77.0

16 500 1270 0.39 0.64 0.90 0.65 0.18 - - - 2267 50.0

17 250 1500 0.17 0.64 1.76 1.27 0.18 0.5 2.0 12.0 2189 23.0

18 750 1110 0.68 0.76 0.63 0.45 0.18 2.5 3.0 15.0 2224 75.0

19 750 966 0.78 0.55 0.58 0.42 0.18 2.0 3.5 8.0 2220 87.0

20 750 1042 0.72 / 0.60 0.43 0.18 2.0 2.5 - 2293 85.0

21 750 1042 0.72 / 0.60 0.43 0.18 2.0 3.0 6.0 2293 88.0

- 58 -

Figure 4.9 a Effect of W/B

Figure 4.9 b Effect of W/C

Figure 4.9 c Effect of W/P

Figure 4.9 Effects of W/B, W/C and W/P on Strength

0

20

40

60

80

100

120

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4Co

mp

ress

ive

str

en

gth

(M

Pa)

Water to binder ratio (W/B)

Effect of W/B in Phase II

0

50

100

150

0.44 0.54 0.64 0.74 0.84 0.94 1.04 1.14 1.24 1.34 1.44 1.54 1.64 1.74 1.84

Co

mp

ress

ive

str

en

gth

(M

Pa)

Water to cement rario (W/C))

Effect of W/C in Phase II

0

20

40

60

80

100

120

0.14 0.15 0.16 0.17 0.18 0.19 0.2 0.21 0.22Co

mp

ress

ive

str

en

gth

(M

Pa)

Water to powder ratio (W/P)

Effect of W/P in Phase II

- 59 -

There is an obvious difference between the fresh mixtures with different W/P. The mixture with

W/P at 0.16 was a kind of dough, and the entrapped air could not be expelled. The mixture with

W/P at 0.18 had suitable consistency, neither sticky nor bleeding or segregating, while the paste

with W/P at 0.20 showed excess bleed water.

Therefore, the favorable water to powder ratio for adequate workability of the mixtures in the

project was 0.18. The pastes with W/P at 0.21 and 0.20 (No.1, No.2, No.3 and No.4 in Table 4.4)

flowed like water so that vacuum grease had to be used to seal the molds to prevent the pastes

from leaking. However, there was no bleeding or segregation observed.

4.3.2 Effect of Residual Packing Density β

The effect of the residual packing density β was not the same as initially presumed (that the

higher the value of β, the better the particle packing would be, as calculated in Table 3.14). The

experiment results (No.15, No.18 and No.19 in Table 4.4 and Figure 4.10) displayed that the

reasonable values are still those displayed in Table 2.1, i.e., 0.58, 0.55 and 0.52. There were too

many coarse particles and not enough fine particles in the mixtures with higher β values, just as

the contents distribution of 12-PT, 6-PT and 3-PT in the mixtures No.15, No.18 and No.19

(Table 4.4). These are also shown in the simulation graphs of particle size distribution produced

by the Lisa program (Figure 4.11).

Figure 4.10 Effects of Residual Packing Density β on Strength

70

75

80

85

90

0.5 0.55 0.6 0.65 0.7 0.75 0.8

Co

mp

ress

ive

str

en

gth

(M

Pa)

Residual packing density β

Effect of Residual Packing Density β

- 60 -

Figure 4.11 a β = 0.55

Figure 4.11 b β = 0.64

No.15

Modified Andreassen: q=0.22gfedcb Particle Size Distributiongfedcb

Particle Size (Micron)

1 10 100 1000 10000

Perc

enta

ge P

ass (

Vol%

)

1.89

4.19

6.55

8.95

11.53

16.97

22.82

29.16

39.60

51.31

69.15

89.94

- 61 -

Figure 4.11 c β = 0.76

Figure 4.11 Simulated Particle Size Distributions of Mixtures with Different β

No.18

Modified Andreassen: q=0.22gfedcb Particle Size Distributiongfedcb

Particle Size (Micron)

1 10 100 1000 10000

Perc

enta

ge P

ass (

Vol%

)

1.89

4.19

6.55

8.95

11.53

16.97

22.82

29.16

39.60

51.31

69.15

89.94

- 62 -

4.3.3 Effect of Shrinkage Reducing Admixtures

Since invented, shrinkage reducing admixtures (SRA) have been used as an effective method in

controlling the shrinkage deformation of cement concrete. Recently, SRA was applied for

concrete curing [40] and as viscosity modifiers of concrete pore solutions [41] to reduce the rate

of chloride diffusion in concrete. In this research, SRA was employed for the first time in ultra

high strength concrete for modifying the cohesion of the fresh mixtures. It effectively reduced

the cohesion and made the fresh mixtures easy to be handled; moreover, the large entrapped air

voids disappeared, although small entrained air bubbles still remained. The setting time was

delayed favorably by SRA, which means there is no loss in rheological properties during the first

30 minutes after mixing, and furthermore, the entrained air bubbles can obviously be eliminated

during this period. If there were suitable contents of Air-Detraining Admixture at this time, the

entrained air bubble amounts would decline more effectively. All the mixtures in Table 4.4 were

cast after 30 minutes, when the mixing procedure was over.

The strength of concrete would be reduced by SRA because of the depressing function of SRA

on the hydration of cement, and the strategy of decreasing water to cement ratio to make up for

the decline in strength was commented on in the literature [41]. This effect of the SRA on the

decline of compressive strength can be seen in mixtures No.6, No.7 and No.8, as shown in Table

4.4 and Figure 4.12.

Figure 4.12 Effects of Contents of Shrinkage Reducing Admixture on Strength

No.6

No.7

No.8 56

58

60

62

64

66

68

10 12 14 16 18 20 22 24 26

Co

mp

ress

ive

str

en

gth

(M

Pa)

SRA content (Kg/m3)

Effect of SRA content

- 63 -

4.3.4 Effect of Particle Size Distributions

Good particle size distributions can effectively modify the rheological properties and result in

increased compressive strength, as shown in mixtures No.1, No.2 and No.3, and the group of

No.12 and No.13, as well as No.20 and No.21shown in Table 3.17 and Table 4.4.

For the group of No.1, No.2 and No.3, because there was too much coarse powder, the LMP 12-

PT was divided as shown in Table 4.5. The particle size distribution curves were shown in Figure

4.13, which illustrates how difficult it is to distinguish the difference in these mixtures and to

know which particle packing was the best. However, the adjusted particle packing distribution as

shown in Table 4.5 had an obvious influence on the fresh mixtures. The mixture with better

packed particles was much easier to mix and achieved higher compressive strength.

Table 4.5 Adjustment of Proportions of Different Particle Sizes Groups

No. LMP 12-PT LMP 6-PT LMP 3-PT

1 844 296 150

2 0 (-384 to 6-PT, -460 to 3-PT) 680 610

3 0 (-584 to 6-PT, -260 to 3-PT) 880 410

For the group of No.11, No.12 and No.13, the mixture No.11 was designed using fine size

particles LMP 1-PT to fill the small voids in the mixture. However, the fresh mixture became

very fluffy. Therefore, double the content of SRA was added to form the mixture No.12 and the

mixture could not flow as well as other mixtures in Table 4.4. Considerably too much fine

powders LMP 1-PT, LMP 3-PT was employed in the mixture No.13. That was also the case with

mixtures No.20 and No.21, and because there were too many fine particles LMP 1-PT, the LMP

3-PT was used, and the compressive strength increased by 3 MPa.

- 64 -

- 65 -

Figure 4.13 Simulated Particle Size Distributions of Mixtures

with Blended Different Particle Sizes of Limestone Powders

- 66 -

4.4 Compressive Strength Characterization in Phase III

4.4.1 Optimization Constituent Proportions for Sustainability

Table 4.6 exhibits the optimized results of the constituent proportions for sustainability. The

compressive strength when both cured in 23°C water for 28d and 85° C water for 3d, achieved

compressive strengths of over 100 MPa with the cement content 300 kg/m3 and silica fume

content 100 kg/m3 (The mixture 7-20 in Table 4.6). All the fresh mixtures were easy to cast, with

only light tapping on the molds needed for compaction. The mixture 9-20 was still a powder

after 20 minutes of mixing because it had too low a cement content (200 kg/m3) to form a cement

paste.

There was no regular relationship, either between the compressive strength and the cement

contents (except for the mixtures cured in 23°C water for 3d, Figure 4.14), or between the

compressive strength and the water to cement ratio (Figure 4.15).

Considering the combination of fresh mixture features and compressive strength, as well as the

costs of constituent materials, the mixture 6-20 in Table 4.6 was selected as the basic mixture

proportion for future research.

- 67 -

Table 4.6 Properties of Optimal Constituent Proportions for Sustainability

ID Mixture details

(kg/m3)

Fresh mixture features

(min)

Compressive strength

(MPa)

GU SL SF LMP

1-PT

Wetting

time

Pasting

time

Mixing

time

23°C Water

curing

3d

85°C

Water

curing

3d 28d

1-20 600 300 100 0 4 6 10

No flow

84.8 88.3 128.3

2-20 550 300 150 100 6 8 12

No flow

82.0 110.8 103.6

3-20 500 300 200 200 8 9 12

Slow

Flow

84.9 89.2 108.5

4-20 450 450 100 100 6 8 12

No flow

80.0 99.5 122.9

5-20 400 450 150 200 7 8 12

No flow

71.1 100.1 134.2

6-20 350 450 200 0 5 6 10

Slow

Flow

64.9 102.9 130.6

7-20 300 600 100 200 5 8 10

Slow

Flow

67.5 113.0 109.4

8-20 250 600 150 0 4 4’30” 8

Slow

flow

52.4 84.6 95.7

9-20 200 600 200 100 Too much powders in volume

and too little cement

/ / /

- 68 -

Figure 4. 14 Effects of Cement Contenst at the Same W/B in Phase III on strength

Figure 4.15 Effects of Water to Cement Ratio in Phase III on Strength

50

60

70

80

90

100

110

120

130

140

250 300 350 400 450 500 550 600

Co

mp

ress

ive

str

en

gth

(M

Pa)

Cement content (Kg/m3)

Effect of Cement Content in Phase III

3d 85°C 28d 23°C 3d 23°C

5060708090

100110120130140

0.3 0.4 0.5 0.6 0.7 0.8 0.9

Co

mp

ress

ive

str

en

gth

(M

Pa)

Water to cement ratio

Effect of Water to Cement Ratio in Phase III

3d 23°C 28d 23°C 3d 85°C

- 69 -

4.4.2 Effect of Water to Binder Ratio in Phase III

Taking mixture 6-20 in Table 4.6 as the benchmark mixture proportion, and adding LMP1-PT to

adjust the particle size distributions and to supplement half of the silica fume, the effect of water

to binder ratio on strength is indicated in Table 4.7 and Figure 4.16. In comparison to mixture 6-

20, there were no obvious variations in compressive strength, but the mixture was much easier to

cast (the mixture 6-20-1 in Table 4.7). The compressive strengths were not as expected when the

water to binder ratio decreased from 0.20 to 0.18 and 0.16 as shown in Table 4.7; this might be

the result of more air voids entrapped with the mixtures becoming drier and more difficult to cast.

The reference [8] stated that “the w/c is not the only dominate parameter influencing

compressive strength” to explain the substantial spread of compressive strength at the same w/c.

The reference [6] explained the influence of water content on the relative density of cement

pastes at the extremely low W/B that the relative density (do/ds) will decrease when the W/B

ratio is lower than the optimized value, i.e., there will be more air entrapped in the mixture.

Table 4.7 Effects of Water to Binder Ratio in Phase III

ID

Mixture

details

(kg/m3)

Fresh mixture features

(minutes)

Compressive strength

(MPa)

Wtotal Wetting

time

Pasting

time

Mixing

time

23°C Water curing 3d

85°C

Water

curing 3d 28d

6-16-1 160 10 15 25

Dry,

casting

difficult

101.7 114.2 127.7

6-18-1 180 6 9 15

Easy to

cast

73.4 102.4 120.4

6-20-1 200 2 3 6

Very

easy to

cast

73.7 103.9 131.3

- 70 -

Figure 4.16 Effecsts of Water to Binder Ratio on Strength in Phase III

60

70

80

90

100

110

120

130

140

0.16 0.18 0.2

Co

mp

rssi

ve s

tre

ngt

h (

MP

a)

W/B

Effect of W/B in Phase III

3d 85°C Water 3d 23°C Water 28d 23°C Water

- 71 -

4.4.3 Effect of Replacing Part of Slag by Limestone Powders

The effect of part of slag being supplemented by LMP 12-PT was provided in Table 4.8 and

Figure 4.17. The compressive strength was improved when no more than 50% slag was replaced

by LMP 12-PT. This is likely the result of the redistribution of particle sizes.

Table 4.8 Effects of LMP 12-PT Replacing Part of Slag

ID

Mixture details

(kg/m3)

Fresh mixture features

(minutes)

Compressive strength

(MPa)

SL LMP

12-PT

Wetting

time

Pasting

time

Mixing

time

23°C Water

curing

3d

85°C

Water

curing 3d 28d

6-16-1 450 0 10 15 25 Dry,

cast

difficult

101.7 114.2 127.7

6-16-1-25 338 112 8 12 20 Dry,

cast

difficult

/ / 131.0

6-16-1-50 226 226 9 12 20 Dry,

cast

difficult

/ / 140.3

6-16-1-75 112 338 8 10 20 Dry,

cast

difficult

/ / 113.8

Figure 4.17 Effects of Part of Slag Supplemented by Limestone Powders on Strength

110

115

120

125

130

135

140

0 112 226 338

Co

mp

ress

ive

str

en

gth

(M

Pa)

LMP 12-PT Content (kg/m3)

Part of SL Replaced by LMP 12-PT

- 72 -

4.4.4 Effect of Size of Fine Limestone Powders

Considering the incomplete hydration of this extremely low W/B SUHSC, and supposing that

only part of the silica fume reacted pozzolanically and the rest of silica fume acted as filler, fine

limestone powders (LMP 3-PT and LMP 1-PT) were used to replace half of silica fume and to

adjust the particle size distribution. However, the results (Table 4.9 and Figure 4.18) indicated

that silica fume could not be replaced by LMP and that the pozzolanic reaction is important to

the compressive strength.

The density of the mixture with LMP 3-PT was higher than of that with LMP1-PT, because the

loose apparent bulk density of 1-PT is 450 g/m3 while that of 3-PT is 600 g/m

3. The filler effect

of LMP 1-PT is worse than that of LMP 3-PT. The mixture with half and half blended LMP 1-

PT and LMP 3-PT had higher compressive strength than that of LMP 3-PT.

Table 4.9 Effects of LMP 3-PT and LMP1-PT

ID

Mixture details

(kg/m3)

Fresh mixture features

(minutes)

Compressive strength

(MPa)

SF LMP

1-PT

LMP

3-PT

Wetting

time

Pasting

time

Mixing

time

23°C Water

Curing

3d

85°C

Water

curing 3d 28d

6-18 200 0 0 8 10 15

Easy

cast

89.8 111.1 145.5

6-18-1 100 100 0 6 9 15

Easy

cast

73.4 102.4 120.4

6-18-3 100 0 100 5 8 15

Easy

cast

76.6 106.7 123.7

6-18-1-3 100 50 50 5 7 15

Easy

cast

82.2 95.7 131.8

- 73 -

Figure 4.18 Effects of Particle Sizes of Fine LMP on Strength

0

20

40

60

80

100

120

140

160

No LMP 1-PT 3-PT 1-PT&3-PT

Co

mp

ress

ive

str

en

gth

(M

Pa)

Type of limestone powders

Effect of part of the silica fume replaced by fine Betocarb

3d 85°C Water curing 3d 23°C Water 28d 23°C Water

- 74 -

4.5 Effect of Curing Regimes

The mixture 6-18-1 in Table 3.23 was cured in water under four different temperatures for three

different time periods: 2d, 3d, and 4d. After the high temperature water curing, one set of the

samples was tested for compressive strength immediately, while the other set of the samples was

cured continuously in the room (23°C, 50% R.H) until 28d before being tested. For the mixtures

which were cured at 23°C, the samples were kept in water until the day they were tested.

The charts (Figure 4.19) indicate that there was no decline in compressive strength in the case of

elevated temperature curing, whether tested immediately or after further room temperature

curing. There was no obvious difference in compressive strength between the curing regimes at

temperatures from 75°C to 95°C and the duration of 2 days to 4 days. However, the elevated

temperature curing conditions increased the compressive strength in comparison with the room

temperature curing condition.

Figure 4.19 Effects of Curing Regimens on Strength

0

20

40

60

80

100

120

140

160

3d28d 2d28d 3d28d 4d28d 2d28d 3d28d 4d28d 2d28d 3d28d 4d28d

23°C 75°C 85°C 95°C

Co

mp

ress

ive

str

en

gth

(M

Pa)

Curing temperature and duration

- 75 -

Chapter 5 Discussion

The literature review and the research results provided information for the following discussion

about the characterization of compressive strength of sustainable ultra-high strength concrete.

It could be presumed that the compressive stress of SUHPC is affected by the synergy of the

three constituent components, i.e., I - fine sand and fillers (as well as the unhydrated

cementitious materials), II – binders ( the hydrated cementitious materials’ pastes), and III - the

interface zones (although the influence of the interfacial zones was much smaller than in

conventional concrete, and the hydrated binder-cementitious material pastes were present only in

the form of a layer enveloping the particles). When the three solid components were subject to

compressive loads, the pores (the resident spaces of the excess water and the gaps between the

packed particles, and the air voids in the matrix) diminished the compressive strength of SUHSC.

This assumption about compressive strength of SUHSC was proven by the reviews of UHPC

proportions in Table 2.3 and the experimental results shown in Figure 4.9 which implied the

effect of W/B. It was also confirmed by the experimental results shown in Figure 4.4 which

revealed that high intrinsic strength of fillers, and the reaction between fillers and cement, could

improve compressive strength of SUHSC.

The same enhancing effect of the reactive fillers was formed elsewhere [38] where β-C2 S was

pre-formed on the surface of quartz fillers to react with cement at extremely low water to cement

ratio. However, in the present case, it must be noted that while the compressive strength

decreased as half of the silica fume was replaced by the LMP 1-PT or LMP 3-PT (Table 4.9 and

Figure 4.18), an adverse trend only appeared when the slag was supplemented by no more than

50% by the LMP 12-PT (Table 4.8 and Figure 4.17). This may be the effect of the difference in

shapes between the LMP particles and the slag particles.

- 76 -

The relation between the compressive strength and the mixture proportion parameters W/C, W/B

and W/P in SUHSC is not the same as it is in conventional concrete. W/P had a distinctly

different influence on the compressive strength than W/B and W/C as shown in Figure 4.9 and

Figure 5.1. The W/P in Phase I was maintained at the same value at 0.17 (Table 3.5) but the

related W/B varied from 0.28 to 0.90, and the W/C shifted from 0.31 to 1.25, respectively

(Figures 5.1 (a) and (b)), and there was a noticeable decline in the compressive strength of

SUHSC. The same trends were also exhibited in Phase II (Figure 4.9), but an irregular trend was

shown in the relation between the compressive strength and the W/C in Phase III (Figure 5.1 (c)

and (d)).

The substantial spread in compressive strength at the same W/B or W/C (Figure 5.1 (a), (b) and

Figure 4.9 (1), (2)) revealed that the compressive strength was not dominated by W/B or W/C.

Reference 8 and 9 indicated that neither W/C (W/B) nor air content was the dominant influence

factor on the compressive strength; in fact, the compressive strength had a relation with the

combination of W/C and air contents. In the present case, the variation of compressive strength

at the same W/P, or the same W/B, or the same W/C, which resulted from the variation of the

types and contents of the constituent materials of SUHSC are displayed in Table 5.1 to Table 5.5.

Combining the data of the compressive strength when cured at 85°C or 90°C in hot water for 3d

in all of the three Phases in the present research, and the data from reference [8], an overview of

the relation between compressive strength and water to binder ratio is shown in Figure 5.2. It is

estimated that the relation between compressive strength and W/C is as follows:

W/B ≤ 0.25, the related compressive strength ≥ 150 MPa;

0.25 ≤ W/B ≤ 0.67, the related compressive strength varied between 100 MPa and

150MPa;

0.33 ≤ W/B ≤ 0.90, the related compressive strength varied between 80 MPa and

100MPa;

- 77 -

Table 5.1 Effect of Constituent Materials on Strength at the Same W/C in Phase I

ID W/C W/B NQS

315

QZP

LMP

12-PT

SF

SKW

GU LMP

3-PT

SL MK fc (MPa)

3d 90°C

A28 0.50 0.41 554 - 254 110 496 496 - - 122.7

A29 0.41 554 - 254 ELKEN

110

496 496 - - 111.7

B1 0.34 554 - 254 110 496 386 110 - 120.4

C1 0.34 554 - 254 110 496 386 - 110 107.7

D1 0.34 554 - 254 110 496 386 55 55 125.1

A6 0.66 0.58 - 806 - 110 496 496 - - 99.1

A18 0.54 160µm

554

- 254 110 496 496 - - 93.1

A21 0.67 0.54 554 - 254 110 496 496 - - 85.7

A22 0.54 1250 µm 554

- 254 110 496 496 - - 87.3

A23 0.54 2000 µm 554

- 254 110 496 496 - - 85.6

A24 0.54 5000 µm 554

- 254 110 496 496 - - 83.9

A25 0.54 554 - 254 ELKEN

110

496 496 -

- 94.1

A7 0.84 0.66 - 806 110 386 608 - - 111.6

A15 0.65 - - 812 112 390 610 - - 89.2

A19 0.65 160 µm

554

- 254 110 388 608 - - 79.9

A26 0.66 554 - 254 ELKEN

110

388 608 - - 76.3

A16 1.17 0.84 - - 812 112 278 722 - - 61.1

A20 0.84 160 µm

554

- 254 110 276 716 - - 63.2

A27 0.85 554 - 254 ELKEN

110

276 716 - - 66.7

- 78 -

Table 5.2 Effect of Constituent Materials on Strength at the Same W/B in Phase I

ID W/B W/C NQS

160

QZP LMP

12-PT

SF

SKW

GU LMP

3-PT

SL MK fC

(MPa)

3d 90°C

A5 0.29 0.33 - 806 - 110 994 0 - - 108.9

A13 0.36 - - 812 112 1000 0 - - 105.5

B1 0.34 0.50 315µm

554

- 254 110 496 386 110 0 120.4

C1 0.50 315µm

554

- 254 110 496 386 0 110 107.7

D1 0.50 315µm

554

- 254 110 496 386 55 55 125.1

A28 0.41 0.50 315µm

554

- 254 SKW

110

496 496 - - 122.7

A29 0.50 315µm

554

- 254 ELKEN

110 496 496 - - 111.7

B2 0.64 315µm

554

- 254 110 386 496 110 - 96.4

C2 0.64 315µm

554

- 254 110 386 496 - 110 112.3

D2 0.64 315µm

554

- 254 110 386 496 55 55 112.4

A18 0.54 0.67 554 - 254 110 496 496 - - 93.1

A21 0.67 315µm

554

- 254 110 496 496 - - 85.7

A22 0.67 1250 µm

554

- 254 110 496 496 - - 87.3

A23 0.67 2000 µm

554

- 254 110 496 496 - - 85.6

A24 0.67 5000 µm

554

- 254 110 496 496 - - 83.9

A25 0.67 315 µm

554

- 254 ELKEN

110 496 496 - - 94.1

A8 0.84 1.18 - 806 - 110 276 716 - - 72.9

A16 1.17 - - 812 112 278 722 - - 61.1

A20 1.18 554 - 254 110 276 716 - - 63.2

A27 1.20 315 µm

554

- 254 ELKEN

110 276 716 - - 66.7

- 79 -

Table 5.3 Effect of Constituent Materials at Same Water to Binder Ratio in Phase II

No fc

3d

85°C

W/B W/C W/P Material contents (kg/m3)

GU SL SF LMP

12-PT

LMP

6-PT

LMP

3-PT

LMP

1-PT

W SP SRA AD

11 85.0 0.33 - 0.18 716 216 72 0 340 0 468 282 54 6 4

12 87.0 - 0.18 716 216 72 0 340 0 468 278 54 12 4

13 90.5 - 0.18 716 216 72 0 340 468 0 278 54 12 4

14 107.0 - 0.18 716 216 72 522 140 146 0 282 54 6 4

15 77.0 0.43 - 0.18 538 161 54 682 210 150 0 280 54 6 4

20 85.0 - 0.18 538 161 54 0 410 0 632 280 54 6 4

21 88.0 - 0.18 538 161 54 0 410 632 0 280 54 6 4

7 59.0 0.61 - 0.17 360 108 36 0 880 396 0 250 56 18 4

8 57.0 - 0.17 360 108 36 0 880 396 0 244 56 24 4

1 42.0 0.76 - 0.21 360 108 36 844 296 150 0 312 56 20 24

2 45.3 - 0.21 360 108 36 0 680 610 0 312 56 20 24

3 48.2 - 0.21 360 108 36 0 880 410 0 312 56 20 24

- 80 -

Table 5.4 Effect of Constituent Materials at Same Water to Cement Ratio in Phase II

No fc

3d

85°C

W/C W/B W/P Material contents (kg/m3)

GU SL SF LMP

12-PT

LMP

6-PT

LMP

3-PT

LMP

1-PT

W SP SRA AD

11 85.0 0.46 0.33 0.18 716 216 72 0 340 0 468 282 54 6 4

12 87.0 0.33 0.18 716 216 72 0 340 0 468 278 54 12 4

13 90.5 0.33 0.18 716 216 72 0 340 468 0 278 54 12 4

14 107.0 0.33 0.18 716 216 72 522 140 146 0 282 54 6 4

15 77.0 0.60 0.43 0.18 538 161 54 682 210 150 0 280 54 6 4

20 85.0 0.43 0.18 538 161 54 0 410 0 632 280 54 6 4

21 88.0 0.43 0.18 538 161 54 0 410 632 0 280 54 6 4

1 42.0 1.06 0.76 0.21 360 108 36 844 296 150 0 312 56 20 24

2 45.3 0.76 0.21 360 108 36 0 680 610 0 312 56 20 24

3 48.2 0.76 0.21 360 108 36 0 880 410 0 312 56 20 24

- 81 -

Table 5.5 Effect of Constituent Materials at Same W/P in Phase II

No fc

3d

85°C

W/P W/B W/C Material contents (kg/m3)

GU SL SF LMP

12-PT

LMP

6-PT

LMP

3-PT

LMP

1-PT

W SP SRA AD

1 42.0 0.21 0.76 1.06 360 108 36 844 296 150 0 312 56 20 24

2 45.3 0.76 1.06 360 108 36 0 680 610 0 312 56 20 24

3 48.2 0.76 1.06 360 108 36 0 880 410 0 312 56 20 24

5 64.9 0.18 0.63 0.87 360 108 36 0 880 396 0 268 56 6 4

10 79.0 0.46 0.70 496 150 110 0 0 546 608 270 90 18 4

11 85.0 0.33 0.46 716 216 72 0 340 0 468 282 54 6 4

12 87.0 0.33 0.46 716 216 72 0 340 0 468 278 54 12 4

13 90.5 0.33 0.46 716 216 72 0 340 468 0 278 54 12 4

14 107.0 0.33 0.46 716 216 72 522 140 146 0 282 54 6 4

16 50.0 0.65 0.90 360 108 36 844 280 146 0 276 54 12 4

17 23.0 1.27 1.76 180 54 18 1004 350 146 0 272 54 6 4

15 77.0 0.43 0.60 538 161 54 682 210 150 0 280 54 6 4

18 75.0 0.45 0.63 538 161 54 900 120 90 0 292 54 6+6 4

19 87.0 0.42 0.58 538 161 54 518 248 200 0 268 54 6 4

20 85.0 0.43 0.60 538 161 54 0 410 0 632 280 54 6 4

21 88.0 0.43 0.60 538 161 54 0 410 632 0 280 54 6 4

6 67.0 0.17 0.62 0.86 360 108 36 0 880 396 0 256 56 12 8

7 59.0 0.61 0.85 360 108 36 0 880 396 0 250 56 18 4

8 57.0 0.61 0.84 360 108 36 0 880 396 0 244 56 24 4

9 92.0 0.40 0.57 496 110 110 808 0 386 0 226 60 18 4

- 82 -

a

b

0102030405060708090

100110120130140

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Co

mp

ress

ive

str

en

gth

(M

Pa)

Water to binder ratio (W/B)

Effect of W/B in Phase I

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4

Co

mp

ress

ive

str

en

gth

(M

Pa)

Water to cement ratio (W/C)

Effect of W/C in Phase I

- 83 -

c

d

Figure 5.1 Effects of W/B and W/C and W/P on Strength

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0.3 0.4 0.5 0.6 0.7 0.8 0.9

Co

mp

ress

ive

str

en

gth

(MP

a)

Water to cement ratio

Effect of W/C in Phase III

0102030405060708090

100110120130140

0.165 0.17 0.175 0.18 0.185 0.19 0.195 0.2 0.205

Co

mp

ress

ive

str

en

gth

(M

Pa)

Water to powder ratio

Effect of W/P in Phase III

- 84 -

Figure 5.2 Overview of Effect of Water to Binder Ratio on Strength

40

50

60

70

80

90

100

110

120

130

140

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Co

mp

ress

ive

Str

en

gth

(M

Pa)

Water to Binder Ratio

Effect of W/B in Phase I, II and III

- 85 -

Chapter 6 Conclusions and Future Work

6.1 Conclusions

1. While most commercially available ultra-high strength concretes require very high

portland cement contents, it was shown that Sustainable Ultra-High Strength Concretes

(SUHSC) could be made with compressive strengths in excess of 140 MPa and with as

little as 350 kg/m3 of Portland cement. The ability to obtain more sustainable, low cement

content SUHSC was reflected in two typical mixtures. One mixture with a compressive

strength of 96 MPa was achieved with only 250 kg/m3 Type GU cement, while 600 kg/m

3

industrial by-product slag was eliminated. The other one, with a compressive strength of

146 MPa, was obtained with a Type GU Portland cement of 350 kg/m3.

2. In this study, the SUHSC matrix was composed of three grades of different sized particles

and entrapped air voids, as well as capillary pores (the gaps between the packed

particles). The coarse particles form the skeleton and the intermediate particles filled the

voids between the coarse particles, while the fine particles filled the voids of the

intermediate particles. Pores and entrapped air voids were scattered throughout the

matrix. All of the particles are bonded by cement or cementitious materials. In the present

case, the coarse particles are fine sand and the intermediate particles are comprised of

cement, slag, silica fume, 12µm limestone powder (LMP 12-PT), 6µm limestone powder

(LMP 6-PT) and quartz powders. The fine particles consist of 3µm limestone powder

(LMP 3-PT) or/and 1µm limestone powder (LMP 1-PT).

3. A mechanical model for the compressive strength of Sustainable Ultra-High Strength

Concrete (SUHSC) was proposed as following: the compressive strength is affected by

the interaction of the three solid constituent components, i.e., I - fine sand and fillers, as

- 86 -

well as the unhydrated cementitious materials, II – binders (the hydrated cementitious

materials), and III - the interface zone. Meanwhile, compressive strength is diminished by

capillary pores and entrapped air voids.

4. The higher the intrinsic strength of fillers, the higher the compressive strength of SUHSC

would be. Reactions between the fillers and cement enhance the compressive strength of

SUHSC. The more reactive the particles, the higher the compressive strength of SUHSC.

These are the reasons that the compressive strength of SUHSC with limestone powders as

fillers is higher than that with quartz powder as fillers at ambient temperature, and the

opposite result would be obtained at elevated temperature.

5. While the type of silica fume had no obvious effect on the compressive strength of

SUHSC, the increased content of silica fume improved the compressive strength of

SUHSC significantly because of the combination function of the filler effect and the

pozzolanic reaction effect on the interface. The higher the content of silica fume in the

range of 100 kg/m3-250 kg/m

3, the higher was the compressive strength of SUHSC. The

highest compressive strength of SUHSC with the SF content of 100 kg/m3 was 140 MPa.

The common amount of silica fume in UHPC used by other researchers is approximately

180 kg/m3 to 250 kg/m

3.

6. Limestone powders can be used as fillers to replace quartz powders, or be used as fillers

together with fine sand. Limestone powders can be used to adjust the particle size

distributions of SUHSC, and can even be used to supplement 50% slag at a content of

226 kg/m3. The largest content of limestone powder used in SUHSC was 1534 kg/m

3

with a compressive strength 61MPa and the SUHSC with highest compressive strength

125 MPa had a limestone powder content 640 kg/m3.

7. There was no direct relation between cement content and compressive strength. As the

cement content was increased from 300 kg/m3 to 600 kg/m

3, the compressive strength

decreased from 128 MPa to 109 MPa.

- 87 -

8. W/P is important to obtaining workability but not for strength.

9. Water content is an important influence on the compressive strength of SUHSC, but it is

not the dominant influencing factor. The compressive strength varied with different types

and contents of the constituent materials at the same W/B, or W/C. However, the optimal

water content for obtaining compressive strengths over 150MPa is no more than 200

kg/m3, and the optimal W/B is less than 0.25.

10. Elevated curing temperatures (from 75°C to 95°C) enhanced the compressive strength

compared with the ambient curing temperature (23°C), and there was no strength decline

at latter ages after the elevated temperature curing.

6.2 Recommendation for Future Work

Sustainable ultra-high strength concrete (SUHSC) is a new material in comparison to

conventional UHSC concrete. There are many unknown issues that need to be explored, such as

the mechanism of the cement hydration with only a layer of water film, alternative design

methods for particle packing, and techniques for controlling the entrapped air content. The

durability and volume stability of SUHS also need to be investigated.

- 88 -

7. References

1. K. L. Scrivener, R. J. Kirkpatrick, 2008, Innovation in use and research on cementitious

material, Cement and Concrete Research Vol.38, pp.128–136

2. D. M. Roy, G. R. Gouda, A. Bobrowsky, 1972, Very High Strength Cement Pastes

Prepared by Hot Pressing and Other High Pressure Techniques, Cement and Concrete

Research, Vol.2, pp.349-366

3. European Patent Application No.80301909.0, Imperial Chemical Industries, Ltd (1980)

4. ‘H. H. Bache, 1981, “Densified Cement Ultrafine Particle-Based Materials”; the second

International Conference on Superplasticizers in Concrete, Ottawa, Canada

5. F.de Larrard and T.Sedran,1994, Optimization of ultra-high –performance concrete by

the use of a packing model, Cement and Concrete Research, Vol.24, No.6, pp.997-109

6. P. Richard and M. Cheyrezy, 1995, Composition of Reactive Powder Concretes, Cement

and Concrete Research, Vol.25, No.7, pp.1501-1511

7. E. Sakai, T. Sugiyama, T. Saito, M. Daimon, 2010, Mechanical properties and micro-

structures of calcium aluminate based ultra high strength cement, Cement and Concrete

Research Vol.40, pp.966–970

8. K. Wille, A. E. Naaman, and G. J. Parra-Montesinos, 2011, Ultra-high Performance

Concrete with Compressive Strength Exceeding 150 MPa (22Ksi): A Simpler Way, ACI

Materuals Journal, Vol.108, No.1, Jan-Feb, pp.46-54

9. K. Wille, A. E. Naaman, Sherif El-Tawil, and G. J. Parra-Montesinos, 2012, Ultra-high

performance concrete and fiber reinforced concrete: achieving strength and ductility

without heat curing, Materials and Structures Vol.45, pp.309–324

10. P. Y. Blais, and M. Couture, 1999, Precast, Prestressed Pedestrian Bridge-World’s First

Reactive Powder Concrete Structure, PCI Journal, September-October, Vol.44, No.5, pp.

60-71

11. S. R. Tan, A. J. Howard and J. D. Birchall, 1987, Advanced materials from hydraulic

cement, Phil. Trans. R. Soc. Lond. A, Vol.322, pp.479-491

12. Young, J. F., 1985, Concrete and Other Cement-Based Composites for Lunar Base

- 89 -

Construction, In: Lunar Bases and Space Activities of the 21st Century. Houston, TX,

Lunar and Planetary Institute, edited by W. W. Mendell, pp.391-397

13. A. A. Griffith, 1921, The Phenomena of Rupture and Flow in Solids, Phil. Trans. R. Soc.

Lond. A, Vol. 221, pp.163-198

14. D. M. Roy, G. R. Gouda, 1973, High Strength Generation in Cement Pastes, Cement and

Concrete Research, Vol.3, pp807-820

15. D. ABRAMS, 1918, Design of Concrete Mixtures, University of Chicago, Lewis

Institute, Structural and Materials Research Laboratory, Bulletin. No. 1, PCA as LS001

16. R. FERET, 1897, Sur la Compacite (Density) des Mortars Hydrauliques, Bulletin de la

Societe d’Encouragement pour I’ Industrie Nationale, Vol.2, pp.1604

17. T. C. POWERS, 1958, Structure and Physical Properties of Hardened Portland Cement

Paste, Journal of the American Ceramic Society, Vol.41, No.1, pp.1-6

18. T. C. POWERS, 1958, 'The physical structure and engineering properties of concrete',

Research Bulletin. No. 90, Portland Cement Association Research Dept, Chicago

19. H. M. Jennings, 1988, Critical Assessment Design of high strength cement based

materials: Part 3 State of the art, Materials Science and Technology, Vol. 4 pp.291-300

20. J. D. Birchall, A. J. Howard & K. Kendall, 1981, Flexural Strength and Porosity of

Cement, Nature, Vol. 289, pp.388-390

21. A. H. M. Andreasen, J. Andersen. 1930, Kolloid Z. Vol.50, pp. 217-228

22. C. C. Furnas, 1928, Relations between Specific Volume, Voids, and Size Composition in

Systems of Broken Solids of Mixed Sizes. U.S. Bureau of Mines Reports of

Investigations, No.2894

23. D. R. Dinger, J. E. Funk, 1992, Particle Packing Ⅱ- Review of Particle of Polydisperse

Particle Systems, Interceram Vol.41 No.2, pp.95-97

24. D. R. Dinger, J. E. Funk, 1992, Particle Packing Ⅲ-Discrete versus Continuous Particle

Sizes, Interceram Vol.41 No.5, pp.332-334

25. F.de Larrard, 1999, Concrete Mixture Proportioning-A Scientific Approach, E&FN Spon

26. H. H. C. Wong, A. K. H. Kwan, 2008, Packing density of cementitious materials: part

1—measurement using a wet packing method, Materials and Structures, Vol.41, pp.689–

701

27. D. P. Bentz, C. F. Ferraris, J. J. Filliben, 2011, Optimization of Particle Sizes in High

- 90 -

Volume Fly Ash Blended Cements, NISTIR 7763

28. C. C. Furnas, 1931, Grading Aggregates, Ⅰ. Mathematical Relations for Beds of Broken

Solids of Maximum Density. Ind &Eng. Chemistry Vol.23 No.9, pp.1052-1058

29. http://www.elkem.no/eway/default.aspx?pid=243&trg=Main_7170&Main_7170=7197:0:

4,4710:1:0:0:::0:0, June 8 2012.

30. T. Zhang, Q. Yu, J. Wei, P. Zhang, P. Chen, 2011, A gap-graded particle size distribution

for blended cements: Analytical approach and experimental validation, Powder

Technology Vol.214, pp.259–268

31. T. STOVALL, F. DE LARRARD and M. BUIL, 1986, Linear Packing Density Model of

Grain Mixtures, Powder Technology, Vol.48, pp.1 – 12

32. F.de Larrard, 1989, Ultrafine particles for the making of very high strength concretes,

Cement and Concrete Research, Vol.19, pp.161-172

33. F. de Larrard, T. Sedran, 2002, Mixture-proportioning of high-performance concrete,

Cement and Concrete Research Vol.32, pp.1699–1704

34. S.M. Iveson, J. D. Litster, K. Hapgood, B. J. Ennis, 2001, Nucleation, growth and

breakage phenomena in agitated wet granulation processes: a review, Powder Technology

Vol. 117, pp.3–39

35. U.S. Department of Transportation, 2006, Publication NO.FHWA-HRT-06-103, Material

Property Characterization of Ultra High-Performance Concrete

36. R. Terrence, 2003, The effect of pozzolans and slag on the expansion of mortars and

concrete cured at elevated temperature, PhD. Thesis, University of Toronto

37. M. R. Jones, L. Zheng and M. D. Newlands, 2002, Comparison of particle packing

models for proportioning concrete constituents for minimum voids ratio, Materials and

structures, Vol.35, pp.301-309

38. Z. Xu, M. Tang and J. J. Beaudoin, 1993, An Ideal Structural Model for Very Low

Porosity Cementitious Systems, Cement and Concrete Research, Vol.23, pp.377-386

39. S. Aydin, H. Yazici, 2010, Effect of Aggregate Type on Mechanical Properties of

Reactive Powder Concrete, ACI Materials Journal, pp.441-449

40. D. P. BENTZ, 2005, Curing with Shrinkage-Reducing Admixtures, Concrete

international, No.10, pp.55-60

41. F. Rajabipour, G. Sant, J. Weiss, 2008, Interactions between shrinkage reducing

- 91 -

admixtures (SRA) and cement paste's pore solution, Cement and Concrete Research,

Vol.38, pp. 606–615