In India, majority of cement produced is of blended variety, with fly ash and blast furnace slag as the mineral admixtures used for blending. Blended cements production reduces clinker production thereby leading to conservation of natural resources and energy and also substantial reduction in the CO2 generation, which is a green house gas. The production of blended cements also leads to utilization of two major industrial wastes, coming from thermal power stations and the integrated steel plants. The application of blended cement in concrete imparts better strength and durability properties to the structure. Keeping these aspects in mind, the presentation illustrates the characteristics of two varieties of blended cements, new to Indian cement industry, namely Portland Limestone Cement (PLC) and Portland High Volume fly Ash Cement (PHFC).

1. NEW BLENDED CEMENTS
by
Dr J D BAPAT
www.drjdbapat.com
INDIAN CEMENT REVIEW CONFERENCE 2014
on
SUSTAINABILITY IN INDIAN CEMENT INDUSTRY
6 JUNE 2014, MUMBAI

2. NEW BLENDED CEMENTS
PRINCIPAL DEVELOPMENT GOALS
 REDUCING CARBON (GHG) EMISSION THROUGH
CLINKER SUBSTITUTION
 REDUCING ENERGY CONSUMPTION
 INCREASED PRODUCTION CAPACITY
REDUCING SOLID WASTE
 MAINTAINING QUALITY : STRENGTH & DURABILITY

3. NEW BLENDED CEMENTS
IS 456 – 2000 PROVISIONS
ADMIXTURES PERMITTED BY INDIAN STANDARD CODE
FOR PLAIN AND REINFORCED CONCRETE i.e. IS 456 – 2000
 FLY ASH (15-35% )
 BLAST FURNACE SLAG OR GGBS (25-70%)
 SILICA FUME (3-10%)*
 RICE HUSK ASH (25-30%)*
 METAKAOLIN (10-25%)*
* Recommended as per common practice

4. NEW BLENDED CEMENTS
 PORTLAND LIMESTONE CEMENT (PLC)
 PORTLAND HIGH VOLUME FLY ASH CEMENT (PHFC)

5. PORTLAND LIMESTONE CEMENT
PLC

6. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
INDIAN & INTERNATIONAL STANDARDS
 INDIAN STANDARD IS 269 - 2013: PERMITS ADDITION OF LIMESTONE UPTO 5%,
AS PERFORMANCE IMPROVER, IN OPC
 EUROPEAN STANDARD EN 197-1 (2000):
 5% LS ADDITION PERMITTED IN ALL 27 APPROVED TYPES, AS MINOR
ADDITIONAL CONSTITUENT (MAC)
 OUT OF THAT, 4 ARE PORTLAND LIMESTONE CEMENT, PERMITTING HIGHER
ADDITIONS OF LS, IN ADDITION TO 5% MAC AS ABOVE
 CEM II/A-L & CEM II/A-LL: 6 TO 20% & CEM II/B-L & CEM II/B-LL: 21-35%
 US STANDARDS:
 ASTM C150: 5% LS ADDITION PERMITTED IN TYPES I TO V
 ASTM C595 & AASHTO M240: 5-15% LS ADDITION PERMITTED IN TYPE IL & IT
CANADIAN STANDARD CSA A3001:
 5% LS ADDITION PERMITTED IN PORTLAND CEMENT
 6 - 15% LS ADDITION PERMITTED PORTLAND LIMESTONE CEMENT

7. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
SIGNIFICANCE OF 15% LIMIT
Matschei et al. 2007

8. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
HOW LIMESTONE WORKS
PARTICLE PACKING – IMPROVED PARTICLE SIZE DISTRIBUTION

9. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
HOW LIMESTONE WORKS
PROVIDES NUCLEATION SURFACES
FOR PRECIPITATION OF HYDRATED CEMENT

10. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
HOW LIMESTONE WORKS
LS REACTS WITH ALUMINATES IN
CEMENT TO FORM CARBOALUMINATES

11. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
LIMESTONE REQUIREMENTS: EN STANDARDS
 CALCIUM CARBONATE > 75%
 TOTAL ORGANIC CARBON (TOC): MAX 0.5%
 CLAY: MAX 1.2 g/100g

12. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
PRODUCTION OF PLC
 METERED PROPORTION OF CRUSHED, DRIED LS FED TO FINISH GRINDING
MILL ALONG, WITH CLINKER & GYPSUM
 LS IS MORE EASILY GROUND THAN CLINKER (HARDER) & GETS
CONCENTRATED IN FINE PARTICLES
 OVERALL FINENESS MUST BE HIGHER, FOR EQUIVALENT PERF (.) TO HAVE
FINENESS OF THE CLINKER FRACTION TO BE SIMILAR TO OPC:
 PRODUCTION RATE IS SLOWED
 SOME ADDITIONAL GRINDING ENERGY REQUIRED BUT IS MORE THAN
OFFSET BY LOWER CLINKER CONTENT & RELATED KILN FUEL SAVINGS
 PARTICLE SIZE DISTRIBUTION IS ENHANCED
 HYDRATION IS ENHANCED BY BOTH PHYSICAL AND CHEMICAL INTERACTION
 SUSTAINABILITY BENEFITS SIGNIFICANT: REDUCED ASSOCIATED CARBON
EMISSIONS & EMBODIED ENERGY (LESS CLINKER)

13. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
PRODUCTION PLC
INTER-GRINDING WITH CLINKER
GRINDING ENERGY CONSUMPTION DECREASES WITH LS REPLACEMENT
Opoczky, L., 1992

14. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
FRESH CONCRETE WITH PLC
 WATER DEMAND & WORKABILITY RELATED TO PARTICLE SIZE
DISTRIBUTION OF LS IN RELATION TO CEMENT
 GENERALLY INCREASED WATER IS NEEDED TO MAINTAIN
CONSISTENCY OF CEMENT PASTES AS LS CONTENT INCREASES
FINE LS PARTICLES ENHANCE OVERALL PARTICLE PACKING OF
BINDER MATERIALS RESULTING IN LESS SPACE FOR WATER
BETWEEN SOLID GRAINS
DECREASING AVERAGE PARTICLE SIZE OF LS GIVES BETTER
EARLY-AGE RHEOLOGICAL PROPERTIES

15. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
FRESH CONCRETE WITH PLC
REDUCED BLEEDING
Specific Surface Area m2/kg
Building Research
Establishment , 1993

16. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
FRESH CONCRETE WITH PLC
HYDRATION
 AS LIMESTONE ACTS AS NUCLEATION
SITES FOR HYDRATION PRODUCTS ITS
INCLUSION INCREASES RATE OF HYDRATION
 LIMESTONE ADDITIONS GIVE EARLIER
PEAK FOR HEAT OF HYDRATION

17. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
MECHANICAL PROPERTIES: CONCRETE WITH PLC
 LS UP TO 5% INCREASES EARLY-AGE STRENGTH DUE TO: IMPROVED PARTICLE
PACKING , INCREASED RATE OF CEMENT HYDRATION & EARLY PRODUCTION OF
CALCIUM CARBOALUMINATE (.) APPLIES TO BOTH INTER-GROUND & BLENDED PLC
 HIGHER REPLACEMENTS: LOSS OF STRENGTH DUE TO DILUTION MUST BE
COMPENSATED BY FINER GRINDING (.) VOGLIS ET AL (2005): SHOWED COMPARABLE
STRENGTHS FOR PC & PLC WITH 15% LS, WHEN PLC WAS GROUND TO 511 m2/kg
COMPARED WITH 303 m2/kg FOR PC
 TSIVILIS ET AL (1999): APPROPRIATE CHOICE OF CLINKER QUALITY, LS QUALITY, %
LS CONTENT & CEMENT FINENESS CAN LEAD TO PRODUCTION OF PLC WITH
DESIRED PROPERTIES, AT LEAST FOR CEMENTS WITH UP TO 15% LS
 TENSILE, FLEXURAL STRENGTH & MODULUS OF ELASTICITY: STANDARD
EQUATIONS APPLICABLE (.) SHRINKAGE SAME BUT CREEP INCREASES

18. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
DURABILITY OF CONCRETE WITH PLC
CONCRETE PERMEABILITY
Matthews, J.D. 1994.

19. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
DURABILITY OF CONCRETE WITH PLC
CHLORIDE DIFFUSION COEFFICIENT
Dhir, R.K., et.al. 2007.

20. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
DURABILITY OF CONCRETE WITH PLC
CARBONATION
Dhir, R.K., et.al. 2007

21. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
DURABILITY OF CONCRETE WITH PLC
CARBONATION
 IN REFERENCE TO HYDRATED PLC, STRENGTH OF PLC AFTER
ACCELERATED CARBONATION WAS 79% HIGHER AT 28 D, EVEN THOUGH
ULTIMATE LS CONTENT IN CARBONATED PLC WAS OVER 40%
 CALCIUM CARBONATES PRODUCED BY ACCELERATED CARBONATION
GETS IMBEDDED IN C-S-H, FORMING INTERMINGLED MICROSTRUCTURE
 HIGH CARBONATION REACTIVITY OF PLC ATTRIBUTED TO FINE PARTICLE
SIZE & EXISTENCE OF LS POWDER NUCLEI FOR CALCIUM CARBONATE
PRECIPITATION
 USE OF PLC IN ACCELERATED CARBONATION OF CONCRETE PRODUCTS
CAN SIGNIFICANTLY CONTRIBUTE TO A NET GAIN IN STRENGTH & CARBON
EMISSION REDUCTION
Ref: Shao Y., et. al. 2014

22. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
DURABILITY OF CONCRETE WITH PLC
SULPHATE RESISTANCE
 STANDARDS DO NOT RECOMMEND USE OF PLC IN SULPHATE
ENVIRONMENT
 AT NORMAL TEMPERATURE, SULPHATE RESISTANCE OF PLC IS
SUBSTANTIALLY IMPROVED WHEN 30-50% SLAG IS ADDED & LS
REPLACEMENT OF 5-15% ARE ALLOWABLE
 SIMILARLY AT 5 C ALSO, SULPHATE RESISTANCE IS SUBSTANTIALLY
IMPROVED WITH THE ADDITION OF SLAG
Ref: Ramezanianpour A. M., 2012

23. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
DURABILITY OF CONCRETE WITH PLC
OTHER DURABILITY PARAMETERS
 SALT SCALING & FREEZE-THAW: LIMITED DATA AVAILABLE FOR AIR-
ENTRAINED CONCRETE SHOW THAT FREEZE-THAW & SALT SCALING
RESISTANCE OF PLC CONCRETE IS COMPARABLE TO THAT OF EQUIVALENT
PC CONCRETE
 ABRASION RESISTANCE: CONCRETES OF IDENTICAL 28-DAY STRENGTH
HAVE SIMILAR ABRASION RESISTANCE, IRRESPECTIVE OF LS CONTENT OF
CEMENT

24. NEW BLENDED CEMENTS
PORTLAND LIMESTONE CEMENT (PLC)
SUMMARY
 LS CEMENTS HAVE BEEN USED IN MANY COUNTRIES SINCE THE 1960’S & EU CEM
II/A 6 TO 20% LIMESTONE CEMENTS ARE THE LARGEST SINGLE TYPE OF CEMENT
CURRENTLY PRODUCED IN EUROPEAN COUNTRIES
 LS FINENESS & PARTICLE SIZE DISTRIBUTION ARE KEY PARAMETRS
ADVANTAGES:
 PLC RESULTS IN REDUCED GHG EMISSIONS
 WHEN PROPERLY OPTIMISED, PLC CONCRETE HAS FRESH PROPERTIES,
BLEEDING & STRENGTH SIMILAR TO OPC CONCRETE
REDUCED PERMEABILITY
 SIMILAR CHLORIDE DURABILITY UP TO 15% REPLACEMENT
 SIMILAR CARBONATION RATE UP TO 15% REPLACEMENT, AT LOW W/C RATIO
 SUBSTANTIALLY IMPROVED SULPHATE RESISTANCE, WHEN PLC UP TO 15% LS, IS
BLENDED WITH SLAG WITH 50% REPLACEMENT
DISADVANTAGE:
 PERFORMANCE IS AFFECTED BY (A) QUALITY OF LS, (B) WHETHER INTERGROUND
OR BLENDED & (C) PARTICLE SIZE DISTRIBUTION

25. PORTLAND HIGH VOLUME FLY ASH CEMENT
PHFC

26. NEW BLENDED CEMENTS
PORTLAND HIGH VOLUME FLY ASH CEMENT (PHFC)
PHFC REFERS TO BLENDED CEMENT PRODUCED IN CEMENT PLANT,
WITH FA REPLACEMENT CEMENT >55%
AT PRESENT HIGH VOLUMES OF FA (>55%) ARE ADDED AS REPLACEMENT
OF CEMENT, AT RMC PLANTS, TO PRODUCE HIGH VOLUME FLY ASH
CONCRETE (HVFAC) (.) IT NECESSITATES ADDITIONAL STORAGE SILOS &
QUALITY CONTROL AT JOB SITE
PHFC IS ONE OPTION, INCREASING AMOUNT OF FA THAT CAN REPLACE
PORTLAND CEMENT (PC) FROM <20% IN CONVENTIONAL MIXES UP TO AS
HIGH AS 55%
PHFC CAN BE PRODUCED EITHER BY INTER-GRINDING FA WITH PC
CLINKER & GYPSUM OR BY BLENDING DRY FA WITH PC (.) SOMETIMES DRY
SUPER PLASTICISER IS ALSO INTERGROUND (.) PRODUCTION OF PHFC
USING INTER-GRINDING METHOD APPEARS MOST COST-EFFECTIVE &
PRACTICAL
REQUIRED TO SATISFY MINIMUM STRENGTH AS PER ASTM C1157, OF 10 &
17 MPa AT 3 & 7 DAYS RESPECTIVELY

27. NEW BLENDED CEMENTS
PORTLAND HIGH VOLUME FLY ASH CEMENT (PHFC)
WHY INTER-GRINDING
EFFECT OF GRINDING ON FA PROPERTIES
 SPECIFIC GRAVITY: INCREASES DUE TO CRUSHING OF PLEROSHERES
AND CENOSHERES AND CONTUES FOR CERTAIN TIME PERIOD OF
GRINDING
 SPECIFIC SURFACE: INCREASES WITH GRINDING TIME, BUT AT THE
EXPENSE OF GRINDING ENERGY
 MORPHOLOGY: OPTIMUM GRINDING PERIOD DOES NOT AFFECT
SPHERICAL SHAPE OF FA PARTICLES SIGNIFICANTLY
 WATER REQUIREMENT OF MORTAR: DECREASES UP TO CERTAIN TIME
PERIOD & LATER INCREASES (.) RELATED TO SPHERICAL SHAPE
 POZZOLANIC ACTIVITY: INCREASES AT RAPID RATE UP TO CERTAIN TIME
PERIOD, LATER RATE DECREASES
 THESE ASPECTS SHOW PHFC SHOULD BE PREFERABLY PRODUCED BY
INTER-GRINDING & GRINDING PERIOD SHOULD BE OPTIMISED.

28. NEW BLENDED CEMENTS
PORTLAND HIGH VOLUME FLY ASH CEMENT (PHFC)
GRINDING SUPERPLASTICISER WITH CLINKER & GYPSUM
WHEN NAPHTHALINE BASED SP WAS VARIED FROM 0-0.9% (MASS OF
CLINKER+GYPSUM):
 GRINDING TIME: SP ACTED AS GRINDING AID & GRINDING TIME REDUCED
TO OBTAIN REQUIRED BLAINE FINENESS
 WATER REQUIREMENT & COMPRESSIVE STRENGTH: SP ADDITION
DURING GRINDING OR SEPARATELY AT THE MIXER PRODUCED SAME
EFFECT
 BLAINE: FIXED ON THE BASIS OF FA, BY CARRYING OUT TRIALS
 BETTER TO ADD SP AT THE GRINDING STAGE
 ADDITION OF SP ALSO ELIMINATES COMPATIBILITY ISSUES AT
CONCRETING STAGE
 PREDETERMINED QUANTITY OF SP MAY BE ADDED TO OBTAIN REQUIRED
CONCRETE SLUMP

29. NEW BLENDED CEMENTS
PORTLAND HIGH VOLUME FLY ASH CEMENT (PHFC)
CONCRETE WITH PHFC
RESULTS OF LABORATORY TRIALS ON PHFC WITH 55% FA*
 FRESH CONCRETE: CONCRETE WITH PHFC REQUIRED MORE SP & AEA,
AS INTER-GRINDING INCREASED FINENESS
 COMPRESSIVE STRENGTH: IRRESPECTIVE OF SOURCE & TYPE OF FA,
CONCRETE WITH PHFC DEVELOPED BETTER STRENGTH COMPARED TO
THAT PREPARED BY SEPARATE ADDITION OF CEMENT & UN-GROUND FA AT
MIXER
 CHLORIDE RESISTANCE: INTER-GRINDING IMPROVED CHLORIDE
RESISTANCE OF CONCRETE
*Ref: Electric Power Research Institute (EPRI), USA, 2001

30. NEW BLENDED CEMENTS
PORTLAND HIGH VOLUME FLY ASH CEMENT (PHFC)
SUMMARY
PHFC IS FACTORY MADE WITH FA REPLACING CEMENT AT 55%
ADDING SP TO CLINKER AT FINISH GRINDING STAGE HELP REDUCE
GRINDING ENERGY & ALSO SOLVES COMPATIBILITY ISSUES AT
CONCRETING STAGE
INTER-GRINDING FA WITH GROUND CEMENT FOR FIXED TIME PERIOD
IMPARTS BETTER CONCRETE PROPERTIES
PHFC HAS VERY GOOD RESISTANCE TOWARDS CHLORIDE PENETRATION

31. NEW BLENDED CEMENTS
 NO CEMENT OR ADMIXTURE CAN OFFSET LOW QUALITY CONCRETE
 DURABLE CONCRETE DEPENDS ON:
 APPROPRIATE MIXTURE PROPORTIONS
 LOWER w/c RATIO
 PROPER PLACEMENT
 CURING
 MAINTENANCE
 WHEN GOOD PRACTICES ARE FOLLOWED, CONCRETE WILL ATTAIN ITS
EXPECTED SERVICE LIFE

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33. NEW BLENDED CEMENTS
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