DURABILITY CONSIDERATIONS FOR DAM CONCRETE IN ACIDIC HYDRO ENVIRONMENT – A CASE STUDY

Concrete can be made which will perform satisfactorily when exposed to various atmospheric conditions, to most waters and soils containing chemicals etc. There are, however, certain aggressive conditions under which the useful life of even the best concrete will be short. Understanding these conditions permit measures to be taken to prevent or reduce deterioration. Peculiar problems like deterioration of concrete due to poor water quality, problem of leaching of lime in seepage galleries, high temperature of water springs inside head race tunnels, acidic hydro environment etc. have been encountered during the pre and post construction investigations at various projects. In addition, the concrete deterioration is directly influenced by various geographical, climatic and ecological conditions. In these conditions, the designing and construction pose challenges for making long term durable concrete. Water plays an important role as the chemical reactions between cement and water for setting and hardening of cement. The long term sustainability of these structures is largely dependent on hydro-environment. Most of the regions in Assam State, Coal mines are wide spread. The autonomy gives freedom to the people to mine at their own will. Mining operations has led to extensive environment degradation and imparts acidic character in natural waters flowing around it. The present paper highlights the study of field and laboratory investigations of river Kopili and its tributaries and also discusses remedial measures for dam concrete for upcoming hydro power project in North East region of India