Development of a low carbon and resource efficient cement
Soumen Maity1, Vaibhav Rathi1, Shashank Bishnoi2
1Development Alternatives, India; 2Indian Institute of Technology Delhi, India
India has been witnessing a rapid transformation due to its growth and ever increasing population. With an average of 4.2 tonnes per capita, India ranked 151 out of 193 countries in the world in 2009 consuming around 4.83 billion tonnes of materials. A major share of this has been contributed from mineral consumption.
In India the construction sector was the second largest and fastest growing sector with regard to material consumption in 2007 accounting for around 20% of all material demand. In construction sector, cement industry is one of the largest emitter of CO2 accounting for approximately 7% of the country’s total CO2 emission. Presently India is the second largest producer of cement in the world and is poised to be the largest by 2050. While India has considerable limestone reserves for producing cement, they may run out by 2030 if the growth rates are sustained. Thus a strong emphasis on resource efficiency and use of alternate materials is essential for the Indian cement industry going forward.
This paper discusses the development of a low carbon cement having the dual advantages of reducing carbon emissions and use of natural resources. The LC3 or limestone calcined clay cement developed is a ternary blend of clinker, calcined clay, crushed limestone and gypsum. The basic advantages are the reduction of clinker factor from 0.75 to 0.50 through the use of non-ceramic grade clays and crushed limestone with high silica or Mg content. Workability and durability tests showed better performance that Portland Pozzolana Cement. The early strength was better than Portland Cement with equivalent strength at 28 days.
Life cycle analysis shows a reduction of carbon emissions by 30% compared to OPC and 11% than PPC. Additionally the LC3 uses around 45% of mine rejects thereby promoting savings in natural resources.