Presentation on theme: "Use of cement: Cement is ONLY one of the ingredients in any applications – well cementing or construction concreting. The specified quality parameters."— Presentation transcript:
1Cement – Specification and Performance Hugh Wang Eduardo Caballero CEMEX USA email@example.com
2Use of cement:Cement is ONLY one of the ingredients in any applications – well cementing or construction concreting.The specified quality parameters of cement are tested without considering other ingredients.Lessons learned from concrete mixtures - interaction of cement with other ingredients can be critical to performance.
3Production of quality well cement involves: ChemistryCa, Si, Al, FeProportioningPhysicalfineness,strength, TT, FFetcGrindingMineralC3S, C2S,C3A, C4AFBurning
4Mineral Desired clinker characteristics for well cement: C3S, C2S, C3A, C4AFWell crystallized alite;Optimize burning condition in order to minimize f-CaO content;Generally very low in C3A content – a challenge for kiln operation.
5Physical Physical properties requirements: Fineness; Thickening time (TT);Free fluid (FF).Physicalfineness,strength, TT,free fluid,etcPotential conflicting response:Fineness vs TT;Fineness vs FF.
6Specifications - ASTM vs API : Fineness: ASTM lowered the limit from 280 to 260 m2/kg;SO3: ASTM adopted performance based specification;D It is permissible to exceed the values in the table for SO3 content, provided it has been demonstrated by Test Method C1038 that the cement with the increased SO3 will not develop expansion exceeding % at 14 days.C3S: No requirement for MSR and HSR cements.C4AF+2C3A: 24 API vs 25 ASTM.
11Discussions – ASTM vs API Minimum blaine 400 m2/kg for API Class-C: if high blaine is intended for early strength, its benefit may be potentially reduced due to the higher water demand.Minimum blaine for other types of cements should be harmonized with ASTM requirements from 280 to 260 m2/kg;. This will improve thickening time performance.Why ASTM revised cement SO3 content?Critical in the mixtures containing supplementary cementitious materials (SCM) and chemical admixtures. Construction industry has gone through the learning process.Potential incompatibility problems in the mixtures shall be considered when complex components are used in slurry.
12Cement hydration rate profile I II III IV VStage I: dissolution Stage II: induction (dormant)Stage III: acceleration Stage IV: decelerationStage V: steadyTime in hoursEnergy release rate mW/gMaximum heat release rateOn-set of acceleration stageConversion of ettringite to mono-sulfate
24Viscosity profile comparison Gypsum addition eliminates high viscosity during early stages
25SO3: Supply - Demand Rule SO3 demandfalse normal flash
26If SO3 supply is greater than demand SO3 demandfalse normal flash
27If SO3 supply is greater than demand SO3 demandfalse normal flash
28If SO3 supply is less than demand SO3 demandfalse normal flash
29If SO3 supply is less than demand SO3 demandfalse normal flash
30RecommendationsIn order to make well cement more robust for slurry mixtures containing SCM and chemical admixtures, the cement SO3 needs to be optimized.The 280 m2/kg blaine requirement needs to be revised to 260 m2/kg, this will help to improve thickening time.The minimum blaine 400 m2/kg for Class-C cement may be eliminated by specifying the strength requirement.Harmonize cement mineral phase calculation to reflect lasted advance in understanding cement chemistry.30