Cement, Energy and Environment

reduced energy consumption when compared with the production of the same quantity of Ordinary Portland cement, thus contributing towards more sustainable construction. Over the years it has been standardized and codified extensively in ASTM & EN standards. However, these cements have not been produced in Indian cement industries so far because there is no IS specification for Portland limestone cement in the country. Considering its presence for more than two decades in Europe it may be worthwhile to explore possibility of extending its introduction in Indian subcontinent in order to provide a suitable alternative to PPC. In fact comparing factors like grindability differences in limestone and fly ashes, availability of suitable low grade limestone at the sites and logistical cost of incorporating fly ash in PPC, making of PLC is an attractive preposition. During extensive developmental work at Central R&D for the last 2 years, it has been found that a 43 grade OPC equivalent grade PLC can be made by employing low/marginal grade limestone, which is currently not usable for cement manufacture. The studies have indicated possibility of using low/marginal grade limestone upto 25% in the PLC for having comparable performance in concrete applications. The proposed blended cement has a potential of • Reducing green house gas emissions during cement manufacturing (by around 20%) • Conserving fast depleting cement grade limestone reserves • Utilizing hitherto unused low grade limestone • Reducing energy consumption in size reduction Thus apart from considering more non– conventional cements mentioned in previous sections, introduction of PLC also deserves some detailed attention which may prove useful in starting our efforts towards sustainability. Action plan and timelines for verifying effectiveness of Products: The proposed cements are completely new in Indian context and are therefore expected to take sustained effort in terms of research and developmental activities, pilot scale trials, plant trials for bulk preparation, detailed investigations in concrete applications and durability, etc. over a period of about 3-5 years. Tentative steps involved in the process can be summarized as given below. Detailed experimental and activity planning may be undertaken later on if the products get conceptual acceptance. 1. Research and developmental activities for verifying functional properties of Calcium– sulfoaluminate cements, mineralized clinker cements, technical feasibility studies and pilot scale preparation over a period of about. 1-2 Years. 2. Preliminary lab studies of reactive belite clinkers are completed. It further requires few plant scale trials for bulk preparation of Reactive belite cement over a period of 3-4 months. The trials will help in understanding process issues, optimizing raw mix designs and cement mill implications while making reactive belite cements. The studies are to be followed by detailed investigations on application of prepared cements in concrete and its durability by making exclusive experimental concrete structures for generating reliable data on differences in normal concrete and concrete made using reactive belite cements, if any. 1 year 3. Making of calcium-sulfoaluminate cements and mineralized clinker cements on plant scale to understand technical feasibility and functional features of such cements and concretes over a period of 2-3 years 4. Co-ordination with National Standards Committee with accommodation of newer cements. The case for PLC may be pursued actively to begin with since considerable amount of experimental results and experience is now available. 1-2 years 5. Identification of suitable manufacturing locations for making newer cements depending upon raw materials constraints, technology upgradation needs, market requirements, etc. for carrying out test runs and market response . 1 year 12 ,.