Calcium Carbonate Fines or finely divided materials for

use in Concrete

NSSGA meeting

Caroline Talbot Ph.D., P.E., FACI

Overview

Potential Market Size

Where used and how

Barriers to entry in North America and Competition

What we have accomplished so far

DATA Performance

What else is needed

Cement Consumption by Market Segments

US Market Size Factors

• 112 millions tons of Cement used in concrete applications in 2007

• 136 million tons of Fly ash produced in the US 50 million tons used in concrete applications EPA Shortage due Solar, Wind, Natural Gas instead of Coal

• Aggregate gradation not always optimum Requires higher level of powder content

• Cement mills closing and not reopening due to new Environmental requirements on CO2 emissions Clinker imports…

• Green movement and LEED

Market segment potential in USA 2007 data

112 mil ton of cement = 450 mil yd3 of concrete

85% RM: 383 mil yd3

7% cement replacement: 35 lbs/yd3

Potential of 6.7 million tons of gcc

In this market it is hard to differentiate gcc vs dust fracture:

Residential market

DOT if we can be counted as cement

15% PC: 68 mil yd3

90% Wet Cast – 61.2mil yd3 10% Dry Cast – 6.8mil yd3

50-60 lbs/yd3 204000 tons of gcc

75% SCC - 46mil yd3

100 lbs/yd3 2.3 million tons of gcc

25% OC - 15 mil yd3

60 lbs/yd3 450000 tons of gcc

Grand total of 10 mil ton market size in 2007

North American Sales Potential PCA data

• Cement used in US 2007 (+ Canada ~ 15-20 Million) • 112 Million tons

• 7.5% replacement: 8.4 million tons + Canada

• That would include cements that includes CC interground, so not all would be for Producers

• Fly ash NA • Under pressure from EPA and Green Energy

• Quality and Availability ???

• 50 Million tons used in the construction market • If GCC takes 5% of that market: 2.5 Mil Tons

Active Clinker / Cement Production locations in the US

All Others

Ash Grove

Buzzi Unicem

Calportland

Essroc

GCC of America

Giant Cement Holding

Lehigh

Holcim

CEMEX

Lafarge

European Market vs. North America

Cement with inter-grinded limestone for >25 years • OPC 5% • Cem II A 6-20% (Lower performance than OPC and also <$) • Cem II B 21-35%

Use of fillers for >20 years • Mineral fillers standard exist since the 1990s • As fillers for aggregate gradation • As part of the cement (K factor since 2006? K25)

Canada has 5% inter-grinded limestone since early 80s • USA just approved few years ago

Canada just created a cement (GUL) with 15% inter-grinded limestone • Finer Blaine • Performance equal to GU and therefore same price • USA introduced also recently

GCC as a filler for aggregate is approved and in CSA and building code but no real guidance on how to design concrete using gcc. The US passed ASTM C 595, ASTM C1797 ACI 211N Proportioning with Limestone fillers

Europe vs North America

• Fillers: New specification exist in NA

• In Europe all considered similar and judged on performance under different exposures

• Fly Ash (in NA, FA is considered 100% cement)

• Slag is considered 100% cement

• Silica Fume is considered 100% cement

• CCF aggregate only

Classes of Concrete and exposure for Concrete

• Completely different in Europe vs. NA

• Data cannot be used

Cement category

Not the same

A few Market Cost figures

Fly Ash US: sells for 30-65 $/tons

• Recycle product

• EPA

• Availability

• Shortage price is going up

Canada: sells for 110-125 $/metric Tons • Distribution controlled by Cement Companies

Cement US: normally sells for 100-120$/T

• Expected to rise because of new environmental laws

• Cement shortage predicted in a few years

Canada: sells 140-160$/metric Tons

A few Market Cost figures

Slag US and Canada

• About same $/T than cement

• Recycle product

Silica Fume

• US and Canada

• 400 $/ton

Metakaolin

• US and Canada

• 200 $/ton

White Cement

• Double the price of Gray Cement

Barriers to Entry and Competition

• Lack of knowledge from Engineering community We need to educate and show how to use This Industry has not pushed into this part of the construction market

• Now we have ASTM Specification for a good/acceptable fillers for use in Concrete for Engineers /

Architect

• Now we ACI mix proportioning information available for our classes of concrete and exposure classes

• DOTs all have different requirements

• CO2 emission reduction versus cement What is the number to use LEED at this point this is not part of recycle content but when interground with cement it is a

LEED point qualifier?

Barriers to Entry and Competition Cont.

• Cement companies have worked together to develop data for their new cement meeting CO2 emission Equivalent performance to regular cement ASR Sulfates Durability Availability (swap with competition companies) Distribution

• Fly ash, Slag, Silica fume Availability (swap) Distribution Price Performance data (ASR, Durability)

• Availability of GCC throughout the US Perception is that there is not much available

• Silo availability at Producers sites

New Technology Introduction: Long term process This is standard for any new product in any Industry • TECH Data on new product use has to be available • ASTM specification C1797 • ACI document (USA) : to show how to use and design concrete using GCC ACI 211N • CSA approves (Canada) Thaumasite • Building code inclusion (both countries) • DOT and provinces codes • Education of potential users through trials mixes and papers published Within the companies wanting to enter the market, the 5 p’s:

Place: product available for distribution everywhere

Price: know cement, fly ash, slag pricing regionally (adjust pricing accordingly)

Product: relevant data for each segment (dry cast, Ready mix, precast (SCC and ordinary)

Promotion: marketing material (TDS, Brochure, table top etc…)

Personnel: trained for this market: this is a very high maintenance segment

What matters to concrete producers

Making money • Cost/yd3 cannot go up • Silo

Meeting Performance requirements

• Cement min and max W/C ratio • Strength • Slump • Set time • LEED points

Mix Design modifications

• Cementitious content • Water • W/C ratio max • Meet minimum strength • Meet workability • Setting time and finishing

What did the Industry in Europe do

Cement Cies have inter-grinded CC but lower perf. than OPC • Lower cost

Over the last 20 years • Worked with the different Research Groups • Develop data in a different Class of Concrete • Using CC with Interground cement as Performance Enhancer • Recently LC3 cements

Worked with the different Associations in place • Develop Specification (Ground CC production) • Acceptance for Use in different applications • Grout, SCC, Regular concrete • Aggregate gradation correction • Built laboratory for internal data development for potential customers • Have product available at a price that competes against cement Now • Use of GCC in concrete application is common • Can be counted as part of cement like fly ash • Application specific • More countries are looking at adopting it as cement replacement • Growing market • Green product, lower cost than OPC

What’s been accomplished so far

ASTM task group formed • as part C09.20 section 1 specification

ACI sub-commitee 211N: • Proportioning Concrete with Limestone Fillers • Part of ACI 211 Proportioning Concrete

Independent lab to develop data for SCC, regular concrete and dry cast but much more is needed Many presentations and research papers

• ICAR 108-1 • Koehler (PH.D thesis and papers) • Dust of fracture • Proportioning with mineral fillers

Talbot • ACI 237 session • Use limestone fillers in SCC • Calcima • SDC/Emerging technology session

NIST (D. Bentz) and Purdue University (Jason Weiss) and others like A. Radlinska

Data so far

Shows excellent performance (I can show the data) • Kamal Khayat in SCC

Lower HRWR demand Lower Skrinkage Faster form pressure decay Adequate durability (freeze-thaw, salt scaling, air void

analysis, RCP) Adequate strength development at 20% replacement Strength loss can be compensated by water reduction

• NRC showed identical performance to GUL Strength, Durability, Shrinkage

• In Dry-Cast good performance at 10% replacement

Does not need to be ground with cement Enhanced fly ash performance seems possible • Paper presented at TRB by NIST • FHWA is doing more tests

Offers to producers • Cost savings • Mix proportioning flexibility

Industry To Do List – Next 1-5 Years ASTM specification • Approved but not all DOT allows it AASHTO (controlled material versus Dust of fracture) ACI • A sub committee as part of 211 N LEED and CO2 emission: need to lobby the case for Green Concrete and cement reduction

Development with the help of Industry Expert of a table like Europe for mix design and clear directions on how to use as max content and %cement replacement in our class of concrete and exposure

Develop Data for regular concrete • Regular applications Case Studies • Sulfate attack • ASR • Dry Cast application: performance data and durability: • Other

Mineral fillers

Ground Product Sand production

Calcium carbonate Other mineralogy Manufactured Dust of fracture

Natural

We must look specifically at the mineralogy and physical properties of

each to evaluate how they will perform in concrete.

Mineral Filler: a finely divided mineral product at least 65% of which passes the U.S. Standard 75 μm (No. 200) sieve (ACI Concrete Terminology, terminology.concrete.org)

ACI Definition

Chemical and Physical Requirements

Parameter Type A Type B Type C

CaCO3, % ≥ 92 ≥ 70 NA

Sum of CaCO3+ MgCO3, % ≥ 95 ≥ 90 NA

Methylene blue value (mg/g) ≤ 3 ≤ 5 ≤ 5

Total Organic Content % ≤ 0.5 ≤ 0.5 ≤ 0.5

Particle size distribution, minimum % passing 300-µm (No. 50) sieve

150-µm (No.100) sieve

75- µm (No. 200) sieve

45- µm (No. 325) sieve

100

100

95

90

100

85

70

65

100

65

Strength Activity Index, % of control at 28d

see note 4

≥ 75 ≥ 75 ≥ 75

Water Requirement, maximum percent of control 120 120 120

Fineness (m2/kg), see note 5 ReportA ReportA ReportA

Moisture Content (%)B ≤ 1 ≤ 1 ≤ 1

A) The purchaser has the authority to approve a change in the fineness or to add a range if needed.

B) The moisture content is listed for materials that can be pneumatically transferred. If material is not pneumatically transferred,

then the purchaser can waive the moisture content requirement.

Where used

• Europe: Has been used in concrete applications for more than 25 years

• Interground

• OPC contains up to 5%,

• GRADE with 5-20%

• GRADE 20-35%

• As a Blend replacing a portion of cement to improve performance/Packing Density (cement-aggregate)

• Canada: CSA recently approved replacement up to 15% on clinker (interground)

• Cement companies mandated to reduce their CO2 emission

• Inter-grinding calcium carbonate with clinker

• If not interground

• At this point CSA says cannot be counted as cementitious

• Often used in formulated bagged products as a filler/cement replacement

Research Significance • US

• ASTM C1797 • Standard Specification for Ground Calcium Carbonate and Aggregate

Mineral Fillers for use in Hydraulic Cement Concrete • ASTM C 595 Blended cement • ASTM C1697 Standard specification for blended SCM • ACI 211 N: Proportioning with Limestone fillers

• Interground versus Blending

• Plenty of data available for use in SCC

• Needed a study to demonstrate performance in ordinary concrete

SCC results (Kamal Khayat)

SCC results (Kamal Khayat)

SCC results (Kamal Khayat)

SCC results (Kamal Khayat)

SCC results (Kamal Khayat)

• Two cement types: GU and GUL

• OMYA Limestone: Betocarb 3 µm and Betocarb 17 µm

Content in the concrete mixes: 7.5%-10%

• Concrete made with w/cm ratios : 0.35 to 0.70

Cementitious content : 250 kg/m3 to 420 kg/m3

For W/Cm = 0.35 series, same superplasticizer dosage (slump: 220 ± 20mm)

Concrete Mixes Parameters

Physical Properties of Cementitious

Properties Cement Limestone

GU GUL 3 µm 17 µm

Blaine fineness (m2/kg) 380 472

Specific Surface (m2/g) 2.92 3.31 5.04 1.26

Passing 45µm, % 97 99 100 96

Specific gravity 3.13 3.08 2.70 2.70

Compressive Strength

7 day 33.5 MPa 36.0 MPa

28 day 41.4 MPa 41.8 MPa

Concrete identification GU-CTL GUL-CTL

BC 3µ BC 17µ

10%

W/(P) 0.33 0.33 0.33 0.32

Cementitious

Composition (%)

Cement 100 100 90 90

Betocarb 0 0 10 10

Total binder (kg/m3) 420 420 420 420

Water (l/m3)* 150 150 150 145

Coarse aggregate (kg/m3) 1020 1020 1020 1020

Fine aggregate (kg/m3) 750 750 750 750

Air content- 60 min (%) 6.5 5.1 7.5 5.3

Unit weight (kg/m3) 2397 2425 2345 2430

Slump (mm)-10 min/60 min 210/155 205/95 235/185 240/130

Composition and Properties of Fresh Concrete (1)

* 4.5 L/m3 of superplasticizer for this series of concrete mixtures

Concrete Type

W/Cm

Durability Factor (%)

Freeze/Thaw

Compressive Strength, MPa

Chloride-ion Penetration,

Coulombs >300 cycles 1d 28d 28d 91d

GU-CTL 0.33 100 34.2 56.8 2458 1558

GUL-CTL 0.33 100 34.0 56.0 2461 1804

BC 3µ 10% 0.33 100 31.7 55.7 2609 1597

BC 17µ 10% 0.32 100 31.3 54.4 2864 1659

Properties of Hardened Concrete (1)

Conclusion • Results show good performance overall as a Blend or

Interground (similar results)

• When added separately • Potential savings • Flexibility of mix design

• Addition rate • Micron size

• Slump retention

• France allows use as partial replacement of cement • For grade smaller than cement • From sources that are controlling

• PSD • Chemistry • Produced in continuous

Study conducted at NIST (D Bentz)

Study conducted at NIST (D Bentz)

Conclusions

•Fine limestone powder additions accelerate setting times of high-volume fly ash (Class

C and Class F) mixtures, even as a delayed addition

•Finer limestone and greater quantities of limestone have a greater acceleration effect

•Even though anatase also has a very small particle size, it does not greatly accelerate

setting times

–This indicates that the limestone likely has both chemical and physical effects at early

ages

•A desired setting time can be engineered by altering the particle size and/or percentage

of the limestone powder by taking advantage of the linear relationship between limestone

surface area and setting time reductions

Study conducted at NIST (D Bentz)

This study focused on mitigating setting time delays via the addition of fine limestone

powders. Other properties that should be investigated include:

–Compressive strength development

•Likely increased by about 10 % at 1 d, less later

–Autogenous shrinkage at early ages

•These results indicate a promising potential for ternary mixtures to achieve equivalent

setting performance to 100% cement systems with substantial cost, energy, and CO2

footprint reductions, successfully achieving both constructability and sustainability.

Study conducted at NIST (D Bentz)

Role of limestone in greater hydration efficiency

(Tim Cost, HOLCIM)

Limestone is not inert, but contributes to hydration both physically and chemically.

Physical mechanisms:

Enhanced particle packing and paste density due to enhanced PSD

“Nucleation site” phenomenon – limestone particles between clinker grains become intermediate sites for CSH

crystal growth

Chemical mechanisms:

Limestone contributes calcium compounds that go into solution and become available for hydration interaction

Calcium carbonate reacts with aluminate compounds to produce durable mono-and hemi-carboaluminate hydrate

crystals

– De Weerdt , Kjellsen, Sellevold, and Justnes, “Synergy Between Fly Ash and Limestone Powder in Ternary Cements,” Cement and Concrete Composites, Vol. 33, Issue

1, January 2011, pp 30-38.

Synergistic strength benefits are, in large part, the

result of documented CaCO3 interaction w/ aluminates

and formation of carboaluminate crystals

(Tim Cost, HOLCIM)

How fine should PLC be ground?

Example fineness trends, PLC vs. clinker and limestone component fractions

(Tim Cost, HOLCIM)

Fineness of the grind is typically used to “tune” 28-day strength to equal that of OPC in C109

mortar and/or simple concrete mixtures (mild or no SCM use)

Benefits of synergies with SCMs become increasingly significant with higher fineness and

higher SCM replacement of cement

Practical limits of increased fineness benefits vary for each plant

How fine should PLC be ground?

(Tim Cost, HOLCIM)

Observed trends suggest that equivalent performance should be

possible with at least 10% higher fly ash replacement, using PLC.

(Tim Cost, HOLCIM)