India is ignorant of the use of fly ash in concrete mix. Projects such as Chennai Metro Rail rely only on cement and don’t permit the use of fly ash which could result in cracks in structures, according to an expert.
While delivering the G S Ramaswamy Memorial Lecture, here to mark the 49th foundation day of CSIR-SERC on Monday, former deputy managing director of Gammon India S A Reddi said that if too much cement was used, several cracks could develop due to shrinkage and thermal effects. He said that engineers as well as builders felt that the use of major quantity of cement in the building projects could increase the strength of the building but they were wrong.
He said that on an average, India used 100 million tonnes of cement per year for concrete mix. This could be reduced by 30 million tonnes, if the construction sector used fly ash. He said this could also improve the life span of a building.
He said, “As per the Euro code, the first step of any design is focused on the life of a structure. While the life of a Euro structure is between 100 and 120 years, the life of an Indian concrete structure that is totally dependent on cement is 50 years.” He also highlighted that Indian construction engineers were unable to design a mix with less cement. Quoting a published paper, Reddi said that India used cement content 30 per cent more than what was being used in developed countries. But then was Indian fly ash of good quality? Reddi said that fly ash from power station was not fit to be used in concrete. “India has only one plant in Nasik to process it. Many of the engineers use fly ash without cleaning,” he said. He added that the cement produced in India was not of good quality when compared to that produced in Europe.