03-11-2014, 12:28 PM
Abstracts: Concrete usage around the world is second only to water. Ordinary Portland cement (OPC) is conventionally used as the primary binder to produce concrete. The environmental issues associated with the production of OPC are well known. The amount of the carbon dioxide released during the manufacture of OPC due to the calcinations of limestone and combustion of fossil fuel is in the order of one ton for every ton of OPC produced. In addition, the extent of energy required to produce OPC is only next to steel and aluminums. Portland cement concrete is a mixture of Portland cement, aggregates, and water. Concrete is the most often used construction material. Due to increase in infrastructure developments, the demand for concrete would increase in the future. The manufacture of Portland cement releases carbon dioxide (CO) that is a significant contributor of the green house gas emissions to the atmosphere. The production of every ton of Portland cement contributes approximately about one ton of CO2. Globally, the world’s Portland cement production contributes 6% of the global loading of carbon dioxide into the atmosphere. By the year 2012, the world cement consumption rate has reached about 4425million tons, meaning that about 265.5 million tons CO2 will be released. In order to address the environmental effect associated with Portland cement, there is a need to use other binders to make concrete. These include the utilization of supplementary cementing materials (SCM) such as fly ash, silica fume, granulated blast furnace slag, rice-husk ash and metakaolin, and the development of alternative binders to Portland cement. Globally, approximately 850 million tonnes of rice harvest is produced each year out of which approximately 160 million ton is produced in India alone. On average 20% of the rice paddy is husk, giving an annual total production of 160 million tonnes. This rice husk when burnt produces 32 million tonnes of Rice Husk Ash (20% approx.). In the majority of rice producing countries much of the husk produced from the processing of rice is either burnt or dumped as a waste. The specific objectives for this study were to compare the following performance characteristics of concrete made with partial replacement of cement by four different combinations of RHA mixtures, to levels of 10%, 15%, 20% and 25% with that of concrete made with no cement replacement at all.