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.