Waste Materials Used in Concrete ManufacturingBy
- Satish Chandra
The environmental aspects involved in the production and use of cement, concrete and other building materials are of growing importance. CO2 emissions are 0.8-1.3 ton/ton of cement production in dry process. SO2 emission is also very high, but is dependent upon the type of fuel used. Energy consumption is also very high at 100-150 KWT/ton of cement produced. It is costly to erect new cement plants. Substitution of waste materials will conserve dwindling resources, and will avoid the environmental and ecological damages caused by quarrying and exploitation of the raw materials for making cement. To some extent, it will help to solve the problem otherwise encountered in disposing of the wastes. Partial replacement of clinker or portland cement by slag, fly ash, silica fume and natural rock minerals illustrates these aspects. Partial replacement by natural materials that require little or no processing, such as pozzolans, calcined clays, etc., saves energy and decreases emission of gases. The output of waste materials suitable as cement replacement (slags, fly ashes, silica fumes, rice husk ash, etc.) is more than double that of cement production.These waste materials can partly be used, or processed, to produce materials suitable as aggregates or fillers in concrete. These can also be used as clinker raw materials, or processed into cementing systems. New grinding and mixing technology will make the use of these secondary materials simpler. Developments in chemical admixtures: superplasticizers, air entraining agents, etc., help in controlling production techniques and, in achieving the desired properties in concrete.Use of waste products is not only a partial solution to environmental and ecological problems; it significantly improves the microstructure, and consequently the durability properties of concrete, which are difficult to achieve by the use of pure portland cement. The aim is not only to make the cements and concrete less expensive, but to provide a blend of tailored properties of waste materials and portland cements suitable for specified purpose. This requires a better understanding of chemistry, and materials science.There is an increasing demand for better understanding of material properties, as well as better control of the microstructure developing in the construction material, to increase durability. The combination of different binders and modifiers to produce cheaper and more durable building materials will solve to some extent the ecological and environmental problems.
Engineers, scientists in concrete manufacturing.
Hardbound, 672 Pages
Published: December 1996
Imprint: William Andrew
- 1. Properties and Use of Solid Residue From Fluidized Bed Coal Combustion Introduction Starting Materials and the Combustion Process The Chemical and Phase Composition of AFBC and PFBC Ashes The Reactivity of Fluidized Bed Ashes The Analysis of Ashes and Testing of Ash Mixes Utilization of Ashes Without Additives Portland Fly Ash Cements and Composite Cements Possible Use of AFBC and PFBC Solid Residue as Constituents of Concrete Mixes The Use of Fluidized Bed Ashes in Multi-Component Portland Clinker Free Cements Autoclaved Products Artificial Concrete Aggregate Fluidized Bed Ashes as Constituents of Portland Cement Clinker Raw Meal Legal and Standardization Aspects, Performance Requirements Conclusions and Recommendations for Future Research References2. Production and Use of By-Product Gypsum in the Construction Industry Introduction Chemical Gypsums Flue Gas Desulphurization Products References3. Fly Ash In Concrete Introduction Fly Ash Characterization Effect of Fly Ash on Fresh and Hardened Concrete Properties Durability Others References4. The Use of Rice Husk Ash in Concrete Introduction Classification of Rice Husk Ash Analysis of The Quality of RHA Hydration Mechanisms of Paste with RHA Early Characteristics of Concrete with RHA The Durability Properties of Concrete with RHA Summary References5. Blast Furnace Slag - The Ultimate Binder Introduction Granulated Blast Furnace Slag Processes of Hydration and Hardening of Slag Cements Cements Using Blast Furnace Granulated Slags Concretes Containing Granulated Blast Furnace Slags Field Experience and Special Use of Slag Alkali Cements Conclusions and Recommendations References6. Red Mud and Phosphogypsum and their Fields of Application Introduction Red Mud Utilization Phosphogypsum Utilization Summary and Conclusions References7. Use of Lignin-Based Products in Concrete Introduction The Nature and Source of Lignins Lignosulphonates Use of Lignosulphonates in Concrete Effects on Hydration of Cement and Microstructure of Concrete Performance in Concrete Factors Influencing the Performance of Lignosulphonate Admixtures Use as Superplasticizers Effects on Durability of Concrete Concluding Remarks Acknowledgments References8. Recycling of Waste as an Alternative Raw Material and Fuel in Cement Manufacturing Introduction Waste Utilization of Waste and Environmental Pollution Control Influence of Using Waste Alternatives to Replace Raw Materials and Fuel on Clinker Formation and the Character of Cement Clinker Influence of Waste Alternatives on Cement Quality Procedure to Use Waste as Alternative Raw Materials and Fuels Other Types of Cement-Utilizing Waste Summary References9. Use of Silica Fume in Concrete Introduction Origin Silica Fumes and Synthetic Silica Evolution of Hydrogen Pozzolanic Reactivity, Hydration and Microstructure Durability Properties Concluding Remarks References 10. Palm Oil Shell Aggregate for Lightweight Concrete Introduction Lightweight Concrete Palm Oil Shell Aggregate Lightweight Concrete Using Palm Oil Shells Comparison with Other Agricultural Wastes Applications Acknowledgments References Index