నైరూప్య

A STUDY ON FLY ASH CONCRETE IN MARINE ENVIRONMENT

S. Bhanu Pravallika, V. Lakshmi

Potable water is the most important ingredient in the making of conventional concrete and concrete is the most widely used material in the world next to water. Only 2.5% of the world’s water bodies are said to be of fresh water and the remaining constitute of sea water. According to the report of the World Meteorological Organization, more than half of the world’s population would not have enough drinking water by 2025. The construction officials in coastal areas have long been facing the challenge of building and maintaining durable concrete structures in a salt water environment. Gradual penetration of sea salts and the subsequent formation of expansive and leachable compounds lead to disintegration of structural concrete. Cement is the most costly and energy intensive component of concrete. The unit cost of concrete can be reduced as much as possible by partially replacing cement with fly ash. Fly ash is available in abundance as a by-product from thermal projects in India. Waste products like fly ash, (which otherwise is hazardous to the atmosphere, may be used as part partial replacement of cement with fly ash and the fly ash) when used in concretes have been known to have higher resistance to chloride ion penetration than concrete made with ordinary Portland cement. In the present study two grades of reference fly ash concrete M20, M25 were prepared using potable water for mixing and curing. The same grades of fly ash concrete were once again prepared using potable water for mixing and cured in sea water. Once again the same grades of fly ash concrete were prepared using sea water for mixing as well as curing. Investigation was carried out for fresh concrete properties and hardened concrete properties on specimens cured for 7, 28 & 90 days.