06-21-2011, 04:45 PM
Supplementary Cementing Materials for Use in Blended Cements
Author: R. Detwiler, J. Bhatty, S. Bhattacharja | Size: 8.6 MB | Format: PDF | Publisher: PCA | Year: 1996 | pages: 106 | ISBN: 0893121428
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Provides information on using fly ash, slag, silica fume and natural pozzolans in the manufacturing of blended cements and the effects of these materials on cement and concrete.
Blended cements have been used extensively in Europe but are not common in North America, where supplementary cementing materials are generally added directly to concrete. However, interest in blended cements in North America is growing because of such advantages to the manufacturer as increased production capacity, reduced CO2 emissions and reduced fuel consumption. Blended cements offer a number of potential advantages to the user as well. These include optimized chemistry for sulfate resistance, optimized particle size distributions for low water demand and the desired reactivity, optimized strength gain characteristics, and superior quality control. However, these benefits are not an automatic result of combining clinker with one or more supplementary cementing materials. There is a distinct possibility of making blended cements that are inferior to portland cement if they are not optimized. This report describes the characteristics of the various components that can be used in blended cements and discusses in detail the mechanisms by which they affect each other and the behavior of concrete. By R.J. Detwiler, J.I. Bhatty, and S. Bhattacharja Contents 1. Introduction 2. Materials 2.1 Blended Cement Standards 2.2 Portland Cement Clinker 2.3 Fly Ash 2.3.1 Production and Availability 2.3.2 Definitions and Classifications 2.3.3 Characterization 2.3.4 Need for Improved Specifications 2.3.5 Reactivity 2.3.6 Processing of Fly Ash 2.4 Blast Furnace Slag 2.4.1 Production 2.4.2 Availability 2.4.3 Characterization 2.4.4 Specifications 2.4.5 Reactivity 2.4.6 Processing 2.5 Condensed Silica Fume 2.5.1 Production 2.5.2 Characterization 2.5.3 Availability 2.5.4 Specifications 2.6 Natural and Manufactured Pozzolans 2.7 Limestone 2.8 Rice Husk Ash 2.9 Cement Kiln Dust 2.10 Supplementary Cementing Materials 2.10.1 Pozzolanic properties 2.10.2 Physical effects 2.10.3 Possible impurities 3. Behavior of Cement and Concrete Containing Supplementary Cementing Materials 3.1 Workability 3.1.1 Rheology 3.1.2 Effect of Fly Ash 3.1.3 Effect of Slag 3.1.4 Effect of Silica Fume 3.2 Setting and Hydration 3.2.1 Hydration of Cement 3.2.2 Effect of Supplementary Cementing Materials 3.2.2.1 Slag 3.2.2.2 Fly ash 3.2.2.3 Silica fume and rice husk ash 3.3 Compressive Strength 3.3.1 Effect of Supplementary Cementing Materials 3.3.2 Silica Fume 3.3.3 Slag 3.3.4 Fly Ash 3.4 Volume Changes 3.4.1 Plastic Shrinkage 3.4.2 Drying Shrinkage 3.4.3 Soundness 3.4.4 Creep 3.5 Durability 3.5.1 Pore Structure and Permeability 3.5.1.1 Curing at normal temperatures 3.5.1.2 Curing at elevated temperatures 3.5.2 Sulfate Resistance 3.5.3 Carbonation 3.5.4 Corrosion of Reinforcement 3.5.4.1 Mechanism of corrosion in concrete 3.5.4.2 Effect of supplementary cementing materials on corrosion 3.5.5 Alkali-Silica Reactivity 3.5.6 Frost Resistance 3.5.6.1 Mechanisms 3.5.6.2 Effect of silica fume 3.5.6.3 Effect of fly ash 3.5.6.4 Effect of slag 3.6 Interaction with Chemical Admixtures 3.6.1 Water Reducers 3.6.2 Air-entraining Agents 3.6.3 Set-controlling Admixtures 4. Optimization 4.1 Background 4.2 Blended Cement Standards 4.2.1 Prescriptive vs. Performance 4.2.2 Building Acceptance 4.3 Obtaining the Desired Properties 4.3.1 Strength and Strength Gain 4.3.2 Durability 4.4 Applications 4.4.1 Checklist for Establishing Criteria 4.4.2 Pavements 4.4.3 Marine Structures 4.4.4 High-rise Buildings 4.4.5 General-use Cement 5. Conclusions and Recommendations
Blended cements have been used extensively in Europe but are not common in North America, where supplementary cementing materials are generally added directly to concrete. However, interest in blended cements in North America is growing because of such advantages to the manufacturer as increased production capacity, reduced CO2 emissions and reduced fuel consumption. Blended cements offer a number of potential advantages to the user as well. These include optimized chemistry for sulfate resistance, optimized particle size distributions for low water demand and the desired reactivity, optimized strength gain characteristics, and superior quality control. However, these benefits are not an automatic result of combining clinker with one or more supplementary cementing materials. There is a distinct possibility of making blended cements that are inferior to portland cement if they are not optimized. This report describes the characteristics of the various components that can be used in blended cements and discusses in detail the mechanisms by which they affect each other and the behavior of concrete. By R.J. Detwiler, J.I. Bhatty, and S. Bhattacharja Contents 1. Introduction 2. Materials 2.1 Blended Cement Standards 2.2 Portland Cement Clinker 2.3 Fly Ash 2.3.1 Production and Availability 2.3.2 Definitions and Classifications 2.3.3 Characterization 2.3.4 Need for Improved Specifications 2.3.5 Reactivity 2.3.6 Processing of Fly Ash 2.4 Blast Furnace Slag 2.4.1 Production 2.4.2 Availability 2.4.3 Characterization 2.4.4 Specifications 2.4.5 Reactivity 2.4.6 Processing 2.5 Condensed Silica Fume 2.5.1 Production 2.5.2 Characterization 2.5.3 Availability 2.5.4 Specifications 2.6 Natural and Manufactured Pozzolans 2.7 Limestone 2.8 Rice Husk Ash 2.9 Cement Kiln Dust 2.10 Supplementary Cementing Materials 2.10.1 Pozzolanic properties 2.10.2 Physical effects 2.10.3 Possible impurities 3. Behavior of Cement and Concrete Containing Supplementary Cementing Materials 3.1 Workability 3.1.1 Rheology 3.1.2 Effect of Fly Ash 3.1.3 Effect of Slag 3.1.4 Effect of Silica Fume 3.2 Setting and Hydration 3.2.1 Hydration of Cement 3.2.2 Effect of Supplementary Cementing Materials 3.2.2.1 Slag 3.2.2.2 Fly ash 3.2.2.3 Silica fume and rice husk ash 3.3 Compressive Strength 3.3.1 Effect of Supplementary Cementing Materials 3.3.2 Silica Fume 3.3.3 Slag 3.3.4 Fly Ash 3.4 Volume Changes 3.4.1 Plastic Shrinkage 3.4.2 Drying Shrinkage 3.4.3 Soundness 3.4.4 Creep 3.5 Durability 3.5.1 Pore Structure and Permeability 3.5.1.1 Curing at normal temperatures 3.5.1.2 Curing at elevated temperatures 3.5.2 Sulfate Resistance 3.5.3 Carbonation 3.5.4 Corrosion of Reinforcement 3.5.4.1 Mechanism of corrosion in concrete 3.5.4.2 Effect of supplementary cementing materials on corrosion 3.5.5 Alkali-Silica Reactivity 3.5.6 Frost Resistance 3.5.6.1 Mechanisms 3.5.6.2 Effect of silica fume 3.5.6.3 Effect of fly ash 3.5.6.4 Effect of slag 3.6 Interaction with Chemical Admixtures 3.6.1 Water Reducers 3.6.2 Air-entraining Agents 3.6.3 Set-controlling Admixtures 4. Optimization 4.1 Background 4.2 Blended Cement Standards 4.2.1 Prescriptive vs. Performance 4.2.2 Building Acceptance 4.3 Obtaining the Desired Properties 4.3.1 Strength and Strength Gain 4.3.2 Durability 4.4 Applications 4.4.1 Checklist for Establishing Criteria 4.4.2 Pavements 4.4.3 Marine Structures 4.4.4 High-rise Buildings 4.4.5 General-use Cement 5. Conclusions and Recommendations
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