Waste Materials Used in Concrete ManufacturingElsevier, 31.12.1996 - 672 Seiten 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. |
Inhalt
1 | |
CHAPTER 2 PRODUCTION AND USE OF BYPRODUCT GYPSUM IN THE CONSTRUCTION INDUSTRY | 53 |
CHAPTER 3 FLY ASH IN CONCRETE | 142 |
CHAPTER 4 THE USE OF RICE HUSK ASH IN CONCRETE | 184 |
CHAPTER 5 BLAST FURNACE SLAG THE ULTIMATE BINDER | 235 |
CHAPTER 6 RED MUD AND PHOSPHOGYPSUM AND THEIR FIELDS OF APPLICATION | 290 |
CHAPTER 7 USE OF LIGNINBASED PRODUCTS IN CONCRETE | 352 |
CHAPTER 8 RECYCLING OF WASTE AS AN ALTERNATIVE RAW MATERIAL AND FUEL IN CEMENT MANUFACTURING | 430 |
CHAPTER 9 USE OF SILICA FUME IN CONCRETE | 554 |
CHAPTER 10 PALM OIL SHELL AGGREGATE FOR LIGHTWEIGHT CONCRETE | 624 |
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28 days acid addition admixture AFBC aggregate air-entraining alite amount anhydrite belite binder blast furnace slag blended cement by-product calcium hydroxide calcium sulphate carbon Cement and Concrete Chemistry of Cement clinker minerals coal combustion components compressive strength Conc concrete mixes crystal decreases desulphogypsum desulphurization dihydrate durability effect ettringite FGD gypsum flue gas fluidized bed combustion fly ash formation formed fuel hardened cement paste hemihydrate hydration hydration reactivity impurities increase industrial waste kg/m kiln lightweight concrete lignin lignosulphonate based lime microstructure mortar N-type natural gypsum oxide particles permeability PFBC phase phosphate phosphogypsum pore Portland cement pozzolanic properties raw materials red mud reduced residue rice husk ash shown in Figure silica fume slag alkaline concrete slump sodium solid solution soluble stabilizes structure sulfate sulfur sulfuric acid superplasticizers surface Table Technology tricalcium aluminate water-cement ratio water-reducing workability