Executive Summary : | India is currently the second largest consumer of cement after China. The cement industry is facing challenges because of limited reserves of limestone that may last for the next 15-20 years and power shortage for the manufacturing process because of a limited supply of coal. It also consumes ahuge amount of energy during its production. This has led to the search of alternative cements which could be less energy intensive, environment friendly and also possess superior property like that of ordinary Portland cement. The exploitation of the potential benefits of the mineralogical constituents of the waste materials could pay the way for such kind of development. Some of these cements could be less carbon cement, calcium sulpho-aluminate-based cement etc. For taking urgent action to combat climate change and its impacts, Research in these areas is essentially needed and this will continue to be the priority area of Indian cement and construction industries.
The primary objective of this research will be to explore methods for the development of low energy low carbon composite ECO cements using low-graded industrial wastes to reduce the environmental impact of cement production, while maintaining or improving current performance Indian standards. Development of low energy- low carbon ECO cementitious binders via synergistic use of low graded industrial wastes for sustainable development. The cement industries are using high-grade fly ash as replacement materials with already manufactured ordinary Portland cement (OPC) clinker. But, till now no attempt has been made to use low-grade limestone slurry waste & low-grade fly ash in the synthesis of OPC cement clinker itself. Because, as such slurry, waste cannot be used in cement because of its high loss of ignition. Every year about 17-18 MT of stone waste is generated from stone Industries which may increase to a level of 25 MT in the coming decades. Waste is a fine white powder (<70 um), enriched with CaCO, and MgCO, as the main constituent. Major issues from the generation of stone waste generation are Groundwater contamination due to landfilling; Air pollution due to an increased level of suspended particulate in the atmosphere and Choking of drains in the rainy season due to unorganized disposal etc. It is therefore imperative to utilize low-grade industrial wastes (after their thermal activation) to develop eco-binders to reduce carbon footprint. Also, the developed cement will help in conserving natural resources by utilizing limestone waste. The developed alternative binder will have the following advantages:
In this project; 3 wastes were supposed to be used i.e. Fly ash (up to 45-50%), Low-grade limestone slurry waste (it is slurry waste and helps minimise mining of limestone because it is disposed off after mining nearby local areas) (up to 30-35%) and Red mud waste/bauxite residue from bauxite mining (up to 15-20%). These things are well stated in the Abstract of Proposal and presentation also. Low-grade limestone slurry waste is a hazardous waste. Low-grade limestone slurry waste is a waste product that is disposed off nearby local areas of mining. Annual disposal can reach up to 20 MT. Therefore it is a huge problem as the particles are lesser than 75 microns, which causes air pollution (by increasing PM2.5. and PM10 levels), land pollution and water pollution. Thus, this waste comes under the hazardous wastes category.
- Up to 30% less CO, than normal OPC clinker;
- Reduction in burning temperature: -250-300°C;
- Fuel consumption: -20-25% less;
- Electricity costs for the manufacturing process: -25-30% less.
Further, the use of low-grade limestone slurry waste will help reduce mining of limestone. Therefore, it is not an environmentally degrading and polluting activity. The pollution activity will be minimized by using this waste without any environmental degradation. Objective: i. Selection of industrial waste raw materials for primarily feed composition in cement kiln, based on chemical constituents. In addition to limestone slurry waste, other waste materials such as fly ash (50% or more) from Thermal Power, gypsum from fertilizer Industry, Red Mud from Alumina Industry may also be used for preparing end products and tested as per BIS Specifications.
ii. Mix proportion and Time-Temperature optimization for ECO-cements.
iii. Development of ECO-binders i.e., OPC-based and CSAB-based Cement.
iv. Evaluation of different cement phase formations (C3S C2S ratio, C3S-C3A ratio, C2S-C4A3S ratio, etc.).
v. Determination of Physico-mechanical, durability, microstructural properties of the ECO cement pastes and mortars.
vi. Studies of the thermodynamics of Ternary CaO-SiO2, -Al203, or quaternary system Cao-SiO2-Al2O3-Fe203, to understand the cement chemistry.
vii. Use of the developed ECO binders in certain building applications.
viii. Longevity and strength of materials/products developed in building construction should be assessed as the properties of the products developed by PI would differ from that of conventional cement. The durability /strength, etc should compare well with that of OPC and meet the standards set by Bureau of Indian Standards (BIS) Code for quality parameters. The products developed should be tested by BIS. |