2§3.3 Portland Cement With Mineral Materials Chapter 3 Cement§3.3 Portland Cement With Mineral MaterialsMineral AdmixtureOrdinary Portland Cement (P.O)Portland granulated Blast-furnance-slag Cement (P.S)Portland-Pozzlana Cement (P.P)Portland fly-ash cement (P.F)Composite Portland Cement (P.C)
3Mineral Admixture Definition Classification Active admixture IntroductionSecondary Hydration ReactionFunction of Active AdmixtureInactive admixture
4Mineral Admixture Definition Improving Property processed or raw mineralmaterials when grindingAdjusting Strength GradeLowering CostsMineral Admixture is the processed or raw with the purpose of improving cement property, adjusting cement grade and lowering costs.
5Classification by performance active admixture (Pozzolan Admixture)and inactive admixture（filling admixture）Classification by performanceInactive admixture（filling admixture）Active admixture(PozzolanAdmixture)
6Active Admixture Introduction It is not hardened after grinding and watering.But after mixed with lime and waterA secondary hydration activity happensTo form hydraulic cementing material activityVolcanic ash activity
8Active AdmixtureAlthough active admixture is not a compound of Portland cement.The replacement of a portion of cement with active admixture changes the properties of the various types of cement.
9Secondary cementing reaction Hydration ReactionFirst reactionPortland cement hydratesTakes place when portland-pozzolan cement is used or when a pozzolan is added to concrete with portland cementSecondary cementing reaction
10Characteristics of Secondary Hydration Reaction Sensitivity to temperatureLow reaction speed at common temperatureHigh reaction speed at high temperatureConsumption Ca(OH)2Improving the structure of pores
11Consumption Ca(OH)2When the calcium silicates hydrate, hydrated lime is one of the products of hydrationThis leaves a reactive soluble salt in the concrete mass and is responsible for the white encrustations and efflorescence which appears in hydraulic structures where the lime has leached to the surface and reacted with CO2.
12Function of Active Admixture Improving products.Lower costs.Better the property of cement.Adjusting strength grade of cement.Expanding application range.Benefiting to prevention of environment.Making full use of industry rubbish.Protecting the environment.
13Better the property of cement Reducing temperature risePozzolanic action occurs very slowly.Consequently the temperature rise is much smaller
14Better the property of cement Reducing alkali-aggregate expansionA pozzolan is an active, amorphous silica.Reacting readily with any alkali in the presence of moisture.The pozzolan, as a very finely divided silica.Readily consuming the Na2O and K2O from the cement.Completely dispersing the expansive silica.Consequently, the alkalis are not available to react with reactive aggregates.
15To Reduce Harmful Effects of C3A The harmful effects of tricalcium aluminates can be reduced by use of a pozzolan.If the pozzolan is used to replace 30 percent of the Portland cement, the percentage of tricalcium aluminates in the total cementing material will also be reduced by 30 percent.
16Types of Active Admixture Fly ashGranulated blast furnace slagOther active admixture
17Types of Active Admixture Fly ash is the flu dust that is precipitated in the smokestacks of coal-burning power plantsGranulated blast furnace slagcomposed of the fine particles of shale in the coal which form tiny spheroids of glass when exposed to the hot flame of the furnace
18Types of Active Admixture Other active admixture such assilica fumediatomiteground pumiceother volcanic rocks
19Inactive Admixture Characteristics It can’t form hydraulic cementing material with gelatification after grinding and mixing with lime in water.QuartzClaySlow cooling slag