internal curing

8/13/2019 Internal Curing

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Internal Curing of Concrete Using Localy Available Material in Bangladesh

by

Different materials have been used for internal curing or self curing in the form of saturated

lightweight fine aggregates, superabsorbent polymers, or saturated wood fibers such as super

absorbent polymers (SAP), crushed return concrete aggregates, pre-wetted lightweight

aggregates (LWA), expanded shale, clays, and slates, recycled waste porous ceramic coarse

aggregate, wooden fiber etc. In Bangladesh, Many of these materials are either unavailable or

costly.

For performance ease and economy, the material that will be used as internal curing material

should have high absorption capacity so that it can provide required water for curing of

concrete, at the same time should be readily available and cheap. The major challenge

associated with internal curing in Bangladesh or other developing countries is to select a

lightweight aggregate, which is cheap and available, and to select the proper percent

replacement. Availability, lightweight and high water absorption capacity of Burnt Clay

Aggregate (Brick) was prime factors to select it as a lightweight aggregate.

In this research different percent replacement is taken and is varied with water cement ratio,

stress-strain, modulus of elasticity, and age with a view to get the optimum percent

replacement of lightweight aggregate.

Research shows that use of brick as lightweight aggregate in internal curing does not

significantly reduce strength and for 20 percent replacement by brick, strength reduction is

minimum.

The research finds out can take a major role in cost elimination in construction especially in

areas having water scarcity

Keywords: Internal Curing, Modulus of Elasticity, Strength, Clay Burnt Aggregate, Brick,

LWA

Introduction

Introductory Remarks

Lightweight aggregate batched at a high degree of absorbed water may be substituted for

normal weight aggregates to provide internal curing in concrete containing a high volume of

cementitious materials. High cementitious concretes are vulnerable to self-desiccation and


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early-age cracking, and benefit significantly from the slowly released internal moisture. Field

experience has shown that high strength concrete is not necessarily high performance concrete

and that high performance concrete need not necessarily be high strength. A frequent,

unintended consequence of high strength concrete is early-age cracking. Blending lightweight

aggregate containing absorbed water is significantly helpful for concretes made with a low ratio

of water-to-cementitious material or concretes containing high volumes of supplementary

cementitious materials that are sensitive to curing procedures. This process is often referred to

as water entrainment. Time dependent improvement in the quality of concrete containing pre

wet lightweight aggregate is greater than with normal weight aggregate. The reason is better

hydration of the cementitious materials provided by moisture available from the slowly released

reservoir of absorbed water within the pores of the lightweight aggregate. The fact that

absorbed moisture in the lightweight aggregate is available for internal curing has been known

for more than four decades. The first documentation of improved long term strength gains

made possible by the use of saturated normal weight aggregates, was reported in 1957 by Paul

Klieger, who, in addition, commented in detail on the role of absorbed water in lightweight

aggregates for extended internal curing. In his 1965 report, Concrete Strength Measurement

Cores vs. Cylinders, presented to the National Sand and Gravel Association and the National

Ready Mixed Concrete Association. Holm (1984) cited the improved integrity of the contact

zone between the lightweight aggregate and the matrix. The improved quality was attributed to

internal curing, and better cement hydration and pozzolanic activity at the interface, and

reduction in stress concentrations resulting from elastic compatibility of the concrete

constituents. The benefits of internal curing go far beyond any improvements in long-term

strength gain, which from some combinations of materials may be minimal or non-existent.

The principal contribution of internal curing results in the reduction of permeability that

develops from a significant extension in the time of curing. Powers showed that extending the

time of curing increased the volume of cementitious products formed which caused the

capillaries to become segmented and discontinuous. It appears that in 1991, Philleo was the first

to recognize the potential benefits to high performance normal weight concrete possible with

the addition of lightweight aggregate containing high volumes of absorbed moisture. Reduced

sensitivity to poor curing conditions in concretes containing an adequate volume of pre wet

lightweight aggregate has also been reported. Since 1995 a large number of papers addressing

the role of water entrainments influence on internal curing and autogenous shrinkage have been

published of which Bentz, et al (1998), is typical. The benefits of internal curing are

increasingly important when supplementary cementitious materials, (silica fume, fly ash,


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metokaolin, calcined shales, clays and slates, as well as the fines of lightweight aggregate) are

included in the mixture. It is well known that the pozzolanic reaction of finely divided alumina-

silicates with calcium hydroxide liberated as cement hydrates is contingent upon the availability

of moisture. Additionally, internal curing provided by absorbed water minimizes the plastic

(early) shrinkage due to rapid drying of concretes exposed to unfavorable drying conditions.

The following Eq. is used to determine the volume of water that must be supplied from the

lightweight fine aggregate to reach complete curing.

Vwat=

(1)

where Vwat(m3 water/m3 concrete or ft3 water/yd3 concrete) is the volume of water that is

consumed during the hydration process due to chemical shrinkage, C fis the cement content,

CS is the chemical shrinkage of the concrete that occurs during the hydration process (usually

about 0.06 lb H2O per lb of cement hydrated or kg of H2O per kg of cement hydrated), max

represents the maximum degree of hydration and can be estimated as (W/C)/0.40 for W/C ratios

below 0.40, When the W/C ratio is greater than 0.40, the maximum expected degree of

hydration can be estimated as one and is the density of water.

This thesis is aimed at the following objectives:

To find out the best percent replacement by lightweight aggregate of concrete with respectto stress-strain, modulus of elasticity.

To observe the effects of percent replacement for different parameter i.e. stress, strain,modulus of elasticity.

To discuss the suitability of internal curing based on the research.Research Significance

Internal curing has been discussed as an added advantage in concrete research. It has wider

prospect and it is possible to get benefit from the internal curing instead of traditional external

curing. Lightweight aggregate are normally used in concrete for the internal curing which are

available, cheap and easy to transport. It has a significant contribution in shrinkage reduction,

enhancing durability, higher performance, improving contact zone, greater utilization of

cement, greater curing predictability, not adversely affect finishability, not adversely affect

pumpability, sustainability, lower maintenance, and hence improving overall concrete

performance. It can aid the construction process economically resulting into effective resource


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utilization. Also considering environmental impact analysis this technique is found as a

desirable one. Additionally introduction of internal curing can open doors for recycling and use

of other potential materials. In this regards, internal curing is expected to be beneficial in many

aspects.

Experimental Work

This Thesis includes the evaluation of several mixes to determine the effectiveness of

lightweight aggregates as an internal curing agent. Free shrinkage specimens and strength

cylinders are evaluated to determine the effects of the lightweight aggregates. The mixes have

water/cement ratio of 0.4, 0.45, and 0.50 with 10%, 20% and 30% of coarse aggregate

replacement. 3-day, 7-day and 28-days of curing period are evaluated for the specimens. A

total of four programs are described. In each program keeping the W/C ratio same the different

percentage of replacement of coarse aggregate were used, and a total of thirty six cylinders to

cast. In each program for each type of replacement three specimens have been made to have

more accurately representative conclusion. The first three programs included only coarse

aggregate replace but the last one was only fine aggregate replacement for w/c ratio 0.45, just to

compare with the earlier ones. The testing machines are also calibrated to ensure their

standards. The humidity and temperatures of testing days had been recorded for more

understanding the testing conditions.

Sieve Analysis of Fine and Coarse Aggregate

The analysis is conducted to determine the grading of materials proposed for use as

aggregates or being used as aggregate. The term fineness modulus (FM) is a ready index of

coarseness or fineness of the material. It is an empirical factor obtained by adding the

cumulative percentages of aggregates retained on each of the standard sieves and dividing

this sum arbitrarily by 100. No. 100, No. 50, No.30, No.16, No.8, No.4, 3/8 in, in, 1.5 in

are the ASTM standard sieves. This test method conforms to the ASTM standard

requirements of specification C 136.

The lab experiments were conducted for two different types of aggregate. These aggregates

are Stone chips (C.A), Burnt Clay Aggregate (brick chips), Sand (F.A), Fine aggregate


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prepared from Burnt Clay Aggregate (brick chips) aggregate. Test results are shown in Figure

1 to Figure 4.

Figure 1: Grain size distribution of coarse aggregate (Stone Chips)

Figure 2: Grain size distribution of coarse aggregate (Burnt Clay Aggregate)

0

20

40

60

80

100

1 10 100

PercentFiner%

Particle Size (mm)

Stone chips as

coarseagggregate

0

20

40

60

80

100

1 10 100

PercentFiner%

Particle Size (mm)

Burnt Clay

Aggregate as

coarse aggregate


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Figure 3: Grain Size Distribution for Fine Aggregate (Sand)

Figure 4: Grain Size Distribution of Fine aggregate (Burnt Clay Aggregate)

Specific Gravity and Absorption Capacity of Fine and Coarse aggregate

Aggregate generally contain pore, both permeable and impermeable, for which specific

gravity has to be carefully determined. With the specific gravity of each constituent known,

its weight can be converted into solid volume and hence a theoretical yield of concrete per

unit volume can be calculated. This test was conducted for determining the bulk and apparent

specific gravity and absorption of fine aggregate.

0

20

40

60

80

100

0.01 0.1 1 10

PercentFine

r%

Particle Size (mm)

Sand as fineaggregate

0

20

40

60

80

100

0.01 0.1 1 10 100

Percen

tFiner%

Particle Size (mm)

Burnt Clay Aggregate as

fine aggregate


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Bulk specific gravity is defined as the ratio of weight of aggregate (oven-dry or saturated

surface dry) to weight of water occupying a volume equal to that of solid including

permeable pores. This is used for

- Calculation of volume occupied by the aggregate in various admixtures containingaggregate on an absolute basis.

- The computation of void in aggregate.- The determination of moisture in aggregate.

Apparent specific gravity is the ratio of the weight of the aggregate dried in an oven at 100 to

C for 24 hrs. To the weight of water occupying a volume equal to that of solid excluding

permeable pores. This pertain to the relative density of the solid material making up the

constituent particles not including the pore space within the particles that is accessible to

water.

Absorption volume is used to calculate the change in the weight of an aggregate due to water

absorption in the pore spaces within the constituent particles, compared to the dry condition.

For an aggregate that has been in contact with water and that has free moisture on particle

surfaces, the percentage of free moisture can be determined by deducting the absorption from

the total moisture content. This test procedure conforms to the ASTM standard requirements

of specification C128. Test results are shown in Table 1.

Test Method: ASTM C128-88


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Table 1: Absorption capacity and Specific Gravity of aggregate

Material

Specific GravityAbsorption

CapacityBulkBulk

(SSD)

Appar

ent

Coarse

Aggregate

Stone 2.65 2.68 2.73 1.1Burnt

Clay

Aggrega

te

1.68 1.99 2.42 18.2

Fine

Aggregate

Sand 2.55 2.59 2.66 1.7

Burnt

Clay

Aggrega

te

1.6 1.95 2.49 22.3

Unit Weight of Fine and Coarse Aggregate

This test procedure covers the determination of unit weight in compacted or loose condition

of fine and coarse aggregates. Unit weight values of aggregates are necessary for use so many

methods of selecting proportions for concrete mixtures. They may also be used for

determining mass/volume relationship for conversions and calculating the percentages of

voids in aggregates. Voids within particles, either permeable or impermeable, are not

included in voids as determined by this test method. This test was conducted according to the

ASTM standard requirements of specification C29. Test results are shown in Table 2.

Table 2: Unit weight of aggregate

Material Type Unit Weight (gm/cm3)

Coarse Aggregate

Stone Chips 1.523

Burnt ClayAggregate

0.905

Fine Aggregate

Sand 1.531

Burnt Clay

Aggregate0.881

Parameters Considered


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Two parameters, water-cement ratio and percent replacement of lightweight aggregate were

considered for this experiment. For water cement ratio 0.40, 0.45, 0.50 three different percent

replacement of 10%, 20% and 30% were considered.

Test Procedure

Stone chips has used as course aggregate was brought to saturated surface dry (SSD)

condition. In the experiment it is done by wagging after pouring water on the coarse

aggregate. A same procedure was applied for the coarse aggregate. Wagging is needed to

make the aggregate homogeneously mixed. To avail internal curing, Burnt Clay aggregates

are used. 1st class bricks are used as a curing agent and coarse aggregate replacer. 3/8

downgraded coarse aggregate are used. Those crushed bricks are sunk under water with the

help of sacks (made of jute) for more than 24 hours to attain saturated condition. Thus, the

brick aggregate are allowed to fill its permeable pores filled completely by water.

Total sixteen mixes were designed for the experimental program. Four were normal mixes

and twelve mixes were to evaluate the effectiveness of using brick as lightweight aggregate

as internal curing agent. Twelve mixes have evaluated three different replacement levels,

10% replacement, 20% replacement and 30% replacement of lightweight aggregate for water

cement ratios 0.40, 0.45 and 0.50. Table 4 shows the concrete mixes of the experimental

program..

Table 4: Concrete mix

MixtureID

ReplacedAggregate

W/Cratio

PercentReplacement

A/CRatio

Water(kg/m3)

Cement(kg/m3)

CA(kg/m3)

FA,Sand

(kg/m3)

Stone(kg/m3)

Brick(kg/m3)

CA-1

CA

0.4

0% 3.34 252.3 628.6 1261.3 840.8 1261.3 0.0

CA-2 10% 3.34 252.3 628.6 1261.3 840.8 1135.1 126.1

CA-3 20% 3.34 252.3 628.6 1261.3 840.8 1009.0 252.3

CA-4 30% 3.34 252.3 628.6 1261.3 840.8 882.9 378.4

CA-5

0.45

0% 3.89 252.3 558.6 1301.3 872.9 1301.3 0.0

CA-6 10% 3.89 252.3 558.6 1301.3 872.9 1171.2 130.1

CA-7 20% 3.89 252.3 558.6 1301.3 872.9 1041.0 260.3

CA-8 30% 3.89 252.3 558.6 1301.3 872.9 910.9 390.4

CA-9

0.5

0% 4.45 252.3 502.5 1341.3 894.9 1341.3 0.0

CA-10 10% 4.45 252.3 502.5 1341.3 894.9 1207.2 134.1

CA-11 20% 4.45 252.3 502.5 1341.3 894.9 1073.1 268.3

CA-12 30% 4.45 252.3 502.5 1341.3 894.9 938.9 402.4

FA-1

FA 0.45

0% 3.89 252.3 558.6 1301.3 872.9 872.9 0.0

FA-2 10% 3.89 252.3 558.6 1301.3 872.9 785.6 87.3

FA-3 20% 3.89 252.3 558.6 1301.3 872.9 698.3 174.6

FA-4 30% 3.89 252.3 558.6 1301.3 872.9 611.0 261.9


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The summery of fresh concrete properties values are given in table 5.

Table 5: Summary of fresh concrete properties

Mixture ID Slump (mm) Unit Weight (kg/m3)

CA-1 114.3 2357.6

CA-2 65 2325

CA-3 55 2316.8

CA-4 78 2251.5

CA-5 190.5 2329

CA-6 205 2347.4

CA-7 215 2306.6

CA-8 220 2290.3CA-9 198 2306.6

CA-10 222.25 2314.8

CA-11 215.9 2308.6

CA-12 215.9 2306.6

FA-1 160 2445.4

FA-2 160 2376

FA-3 148 2337.2

FA-4 190 2335.2

The 0% (percent) replacement is kept under water for normal external curing. the other

%replacements are kept at almost constant humidity at normal temperature around 25 0c.

After 3, 7, 18 days, the cylinders are tested and Stress and corresponding strain are found

from it. Thus the experiment is ready for analysis

Specimen were made for the following tests.

Compressive strength development (ASTM C 39)

6 12 in normally cured cylinders without aggregate replacement . Three cylinderswere tested at 3 days, 7 days, 28 days. 6 12 in internally cured cylinders with aggregate replacement of 10%, 20%, 30%.Three cylinders were tested at 3 days, 7 days, 28 days

Modulus of Elasticity (ASTM C469)

6 12 in normally cured cylinders without aggregate replacement. Three cylinderswere tested 28 days.

6 12 in internally cured cylinders with aggregate replacement of 10%, 20%, 30%.Three cylinders were tested at 28 days.


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Result and Discussion

Required and Supplied Curing Water

Eq. 1 gives the amount of water required for complete curing. From the absorption capacity,

the amount of lightweight aggregate and the amount of water supplied by lightweight

aggregate is determined.

Table 6 shows that, curing agent (crushed brick) has the potential to provide concrete with

required curing water, which helps concrete to attain full due strength. Nevertheless, 10

percent replacement by lightweight aggregate (for both CA and FA) requires a huge amount

of water for complete curing. Due to this reason concrete cannot be cured properly. Thus,

cannot gain full strength. On the other hand, 30 percent replacement (for both CA and FA)

provides huge amount of excess water, which also prevents concrete from gaining due

strength.

water requred

for curing

internal curing is

working

wrto strength

wrto E

Reason to

choose CA Graph

& economy

% selection


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Table 6: Water requirement in curing according to Bentz and Snyder and the amount of water

supplied by lightweight aggregate

Replaced

Aggregate

W/CRatio

Percen

t

Replacemen

Brick

,

a(kg)

(kg

)

CS

Absorption

capacity

,b

Vwat

(fr

om

Eq2.9)

kg

supplied

throug

h

internal

curing

c

Extrawater

needed

(C-Vwat)

(kgperm

3)

CA

0.4

0% 0 628 0.07

18.2

44.0 0.0Normally

Cured

10% 126 628 0.07 44.0 22.9 -21.05D

20% 252 628 0.07 44.0 45.9 1.92

30% 378 628 0.07 44.0 68.8 24.87

0.45

0% 0 558 0.07 39.1 0.0 NormallyCured

10% 130 558 0.07 39.1 23.7 -15.42

20% 260 558 0.07 39.1 47.3 8.27

30% 390 558 0.07 39.1 71.0 31.95

0.5

0% 0 502 0.07 35.2 0.0Normally

Cured

10% 134 502 0.07 35.2 24.4 -10.79

20% 268 502 0.07 35.2 48.8 13.6330% 402 502 0.07 35.2 73.2 38.04

FA 0.45

0% 0 558 0.07

22.3

39.1 0.0Normally

Cured

10% 87.2 558 0.07 39.1 15.9 -19.63

20%174.

4558 0.07 39.1 31.7 -0.16

30%261.

6558 0.07 39.1 47.6 19.30

DNegative value indicates additional requirement of water for complete curing.


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Effect on Physical Properties

Effect of percent replacement of coarse aggregate as well as fine aggregate on internal curing

concrete has been observed from two points of views.

a) compressive strength and

b) modulus of elasticity.

4.3.1 Effect on Compressive Strength:

Figure 4.1 to figure 4.3 represent the variation of compressive strength for a particular W/C

ratio for different coarse aggregate replacement percent. Strength decreases with the increase

of replacement percent for internal curing concrete. For a particular W/C ratio with zeropercent replacement of coarse aggregate, normally cured concrete shows the higher strength

than internal curing concrete with higher replacement of coarse aggregate.

Figure 4.1: Figure: Strength Vs. Age for W/C ratio 0.40 (CA replacement)

0

1000

2000

3000

4000

5000

6000

0 5 10 15 20 25 30

Strength(psi)

Age (Day)

CA-1

CA-2

CA-3

CA-4


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Figure 4.2: Strength Vs. Age for W/C ratio 0.45 (CA replacement)

Figure 4.3: Strength Vs. Age for W/C ratio 0.50 (CA replacement)

0

500

1000

1500

2000

2500

3000

3500

4000

0 5 10 15 20 25 30

Strength(psi)

Age (Day)

CA-5

CA-6

CA-7

CA-8

0

500

1000

1500

2000

2500

3000

3500

0 5 10 15 20 25 30

Strength(psi)

Age (Day)

CA-9

CA-10

CA-11

CA-12


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Figure 4.4: Strength Vs. Age for W/C ratio 0.45 (FA replacement)

4.3.2 Effect on Modulus of Elasticity:

Figure 4.4 represents that modulus of elasticity varies linearly with percent replacement of

aggregate for a particular W/C ratio. Modulus of elasticity is higher in low percent

replacement on a certain W/C ratio. Comparing to the percent replacement of Coarse and

Fine aggregate keeping the W/C ratio same (0.45), Fine aggregate replaced concrete shows

higher Modulus of elasticity than the coarse aggregate replaced concrete. Modulus of

elasticity of different concrete mix for different aggregate replacement percentage is in

Appendix B.

0

500

1000

1500

2000

2500

3000

3500

0 5 10 15 20 25 30

Strength(psi)

Age (Day)

FA-1

FA-2

FA-3

FA-4

0

500

1000

1500

2000

2500

3000

3500

4000

0% 5% 10% 15% 20% 25% 30% 35%

ModulusofElasticity(ksi)

Replacement of CA, %

WC Ratio 0.4

WC Ratio 0.45

WC Ratio 0.5


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Figure 4.4: Modulus of elasticity Vs Replacement

Figure 4.5 represents that, variation of modulus of elasticity with strength of concrete with

aggregate having different percent of aggregate replacement. As replacement percentage

increases, strength of the concrete reduces as well as the modulus of elasticity. Brick chips

have lower strength than stone chips.

Figure 4.5: Modulus of elasticity Vs Strength

Reason to choose CA over FA

0

500

1000

1500

2000

2500

3000

3500

4000

0 5 10 15 20 25 30

Strength(psi)

Age (Day)

CA-5

FA-1

0

500

1000

1500

2000

2500

3000

3500

0 5 10 15 20 25 30

Strength(psi)

Age (Day)

CA-6

FA-2


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strength reduction percentage is minimum at twenty percent coarse aggregate replacement.

Specific percent replacement can be obtained from Fig. 4.7 for different W/C ratio.

Figure 4.6: Strength Vs Percent Replacement

Table 4.2: Percent strength reduction

%

Repacement

w

eihtbasis

CA FA

W/C

ratio 0.4

W/C

ratio

0.45

W/C

ratio 0.5

W/C

ratio 0.5

Strength

(psi)

Strength

reduc

tio

Strength

(psi)

trengt

reduc

tio

Strength

(psi)

Strength

reduc

tio

Strength

(psi)

Strength

reduc

tio

047

62

31

56

24

22

22

81

1

0

47

540.2

29

18

7.

5

18

03

25.

6

20

14

11.

7

2

0

48

88

-

2.6

29

85

5.

4

24

030.8

23

30

-

15.

7

3

0

43

50 8.7

29

45

6.

7

20

48

15.

4

21

03 9.7

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

0 5 10 15 20 25 30 35

StrengthReduction,

%

Burnt Clay Aggregate (CA), %

WC Ratio 0.4

WC Ratio 0.45

Wc Ratio 0.5


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Figure 4.7: Strength Reduction Vs. Percent Replacement (FA) for different W/C ratio

It will be recalled that, at a given degree of hydration, the w/c ratio determines the porosity of

the cement paste. Thus, the relation of equation accounts for the influence of the total volume

of voids on strength, i.e. gel pores, capillary pores and entrapped air. With an increase in age,

the degree of hydration generally increases so that strength increases. It should be

emphasized that strength depends on the effective w/c ratio, which is calculated on the basis

of the mix water less the water absorbed by the aggregate; in other words, the aggregate is

assumed to use up some water so as to reach a saturated and surface-dry condition at the

time of mixing.

4.3 Effect of water cement ratio

Effect of water cement ratio on internal curing concrete has been observed on two points of

view. Water cement ratio has an emerging effect on concrete compressive strength and

modulus of elasticity. Workability of concrete greatly depends upon water cement ratio as

seen in normal concrete. Higher the water cement ratio so the workability increases and vice-

versa. Effect of water cent ratio on concrete compressive strength and its modulus of

elasticity is discussed below.

4.3.1 Effect on Strength


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Figure 4.1 to Figure 4.3 represent the variation of compressive strength for a particular coarse

aggregate replacement percent for different W/C ratio at different age. Strength decreases

with the increase of water cement ratio for internal curing concrete. For a particular w/c ratio

with zero percent replacement of coarse aggregate, normally cured concrete shows the higher

strength than internal curing concrete with higher replacement of coarse aggregate. Maximum

strength is found for w/c ratio 0.40 both for normal curing and internal curing concrete.

Figure 4.3:Strength vs. w/c for 3days

500

1000

1500

2000

2500

0.35 0.4 0.45 0.5 0.55

Strength,(psi)

WC Ratio

CA 0% Replaced

CA 10% Replaced

CA 20% Replaced

CA 30% Replaced


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Figure 4.2:Strength vs. w/c ratio for 7 days

Figure 4.1: Strength vs. w/c ratio for 28 days

4.3.2 Effect on Modulus of Elasticity

1500

2000

2500

3000

3500

4000

0.35 0.4 0.45 0.5 0.55

Strength,(psi)

WC Ratio

CA 0% Replaced

CA 10% Replaced

CA 20% Replaced

CA 30% Replaced

2000

2500

3000

3500

4000

4500

5000

0.35 0.4 0.45 0.5 0.55

Strength,(psi)

WC Ratio

CA 0% Replaced

CA 10% Replaced

CA 20% Replaced

CA 30% Replaced


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internal curing

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