The Hindu 28.07.2010
CDMM develops Geo-Polymer Concrete without cement
Special Correspondent
— Photo: D. Gopalakrishnan 
CONSTRUCTIVE: S.K. Sekar, Director, Centre for Disaster Mitigation and Management, VIT speaking on at a seminar organised at the Build Expo inside the fort in Vellore on Monday.
VELLORE: The Centre for Disaster Mitigation and Management (CDMM), VIT University, Vellore has developed the Geo Polymer Concrete (GPC) without cement, as an effective alternative to cement concrete, on a par with the standards of the GPC developed by Curtin University, Australia, according to S. K. Sekar, Director of CDMM and Senior Professor of Civil Engineering, VIT.
Speaking on “Alternative Building Materials'' at a seminar held as part of the Build Expo organised by Tamil daily Dinamalar in association with the Builders Association of India (BAI), Vellore Centre, at the fort maidan here on Monday, Prof. Sekar said that GPC has been produced by using 100 per cent fly-ash (alternative to cement), river sand, jelly (broken stones) and water mixed with chemicals comprising sodium silicate solution, sodium hydroxide solution and super plasticizer. The CDMM has proved through laboratory experiments that the strength of the GPC produced at the laboratory was equal to the M-20, M-30 and M-40 grades of cement concrete.
The CDMM Director, however, said that GPC could be used only for making pre-fabricated structures since it has to be subjected to hot air curing or steam curing which can be done only in closed chambers, after 24 hours of moulding. It could be used for making any type of insulation work, panels and partition walls of various dimensions. In the light of the need to use eco-friendly construction materials to prevent global warming, GPC meets the need as it avoids the use of cement, which involved atmospheric pollution in its production process.
Prof. Sekar said that Manufactured Sand (M-sand), which is nothing but crushed 40-mm granite stones passed through a 4.75-mm sieve, can be used as an alternative to river sand. By using M-sand, it was possible to totally replace river sand in construction of buildings, and thus save the rivers, which have been overexploited for sand. Over-exploitation of river sand has led to the reduction of the groundwater table in the river. Continuous exploitation of sand would reduce the water-holding capacity of the river, since it is the sand, which retains water in the river. “If we remove the filter bed, we cannot get pure water at all”. Removal of sand also leads to the weakening of structures such as abutments of bridges across rivers. River sand could also be replaced by using foundry waste sand. The foundry industry is ready to supply foundry waste sand free of cost, which can be utilised by the construction industry. Foundry waste sand could also be used for making paving tiles and hollow blocks, he said.
The Senior Professor of Civil Engineering said that the School of Mechanical and Building Sciences of VIT in 2004 laid a low-cost concrete road on the VIT campus, using fly ash (as an alternative to cement) and foundry waste sand as an alternative to river sand, and achieved a saving of Rs.one lakh per km length. Red bricks could be replaced by using FaL-G (fly ash, lime, gypsum) bricks, in order to avoid the exploitation of soil. Considering the fact that 60 per cent of the project cost for buildings goes towards procurement of materials, it was possible to reduce the construction cost and ensure greater durability by using quality alternative materials, he said.
During the question-and-answer session, Prof. Sekar said that industry wastes available in the vicinity of the construction site alone should be used to replace conventional building materials in order to achieve savings.
He said that no alternative to steel has been developed so far. The results of the VIT's experiments in the use of alternative building materials have been sent to the District Rural Development Agency, he said.
R. Anbu, Chairman, S. Rajagopal, general council member, S. Anandan, secretary and G. Ramganesh, former president of the BAI, Vellore Centre, participated in the seminar.
