Cement, Energy and Environment

·. The blending of portland cemen t w ith pozzolanic materials produces portland pozzolana cement and is in use from the year 1880 onwards. The availability of fly ash boos ted up the use of Pozzolana cement from 1930 onwards. The use of electro-static precipitators in thermal power plants helped in producing high quality of fly ash with les·ser loss of ignition and higher content of siliceous materials. The use of such high quality fly ash through blending or inter grinding with Portland cement has been able to produce a binding material which is not only comparable with ore but in many characteristics it smpasses the performance of OPC especially in aggressive environmental conditions. This paper discusses the over all quality perception of PPC, recent changes incorporated by Bureau of Indian Standards (BIS) and steps taken by major cement plants to produce high quality PPC. These s teps are resulting in improving the share of PPC in the total production of cement in India in recent years. At present the quali ty of PPC is mainly regulated through the following three IS codes issued by BIS. IS 3812-1987 Indian Standard specification for fl yash for use as pozzolana and admixture (draft revision in ci rculation) IS 1489 (Part I) 1991 Indian Standa rd Spec ifi ca tion for Portl and Pozzo lana Cement Fly Ash based (amended in the year 2000) IS 1489 (Part II) 1991 Indian Standard Spccifica ti on for Po rt land Pozzolana Cement Calcined clay based (amended in the year 2000) The factors are d iscussed in detail in this paper. The quality of fly ash from major TPPs meets requirements of revised draft code IS3812:2000. The confidence of consumers in the usage of PPC can further be increased through the following; + The fly ash supplied by TPP should conform to revised draft code IS;3812 and a third party certification can be made manda tory + The cement plants should have dry collection system of fly ash and storage in silo in the p lan t. Appropriate .dosing system and weigh-feeders to ensure accurate quantity. It can be enforced by regulatory authorities such as BIS at the time of granting/ renewing license. + Consumers or Consumer forums can visit TPPs and cement plants to ascertain the quality systems. • • • • • The processing of fl y ash should be considered where appropriate quality fly ash is not avail able from TPP. Data and procedure concrete mix design with PPC should be developed centrall y a.1d disseminated at all levels. Adequate data should be generated on performance of PPC in actual field and experience shared with o ther fellow engineers/ decision makers. Tra ining end-consumers and other professionals in the use of PPC. The introduction of grading in PPC by BIS will further bui ld confidence of consumers.