DURABILITY OF HIGH STRENGTH CONCRETE

摘要

Concrete is an important versatile construction material used in wide variety of situations. While taking a building material, it is very important to consider its durability as it indirectly affects on economy, serviceability and maintenance. The durability of concrete depends upon its resistance to deterioration caused by external as well as internal agents. The external agents are like weathering, natural or industrial liquids and gases and aggressive environment. The internal agencies are like harmful alkali-aggregate reactions, volume changes due to incompatibility of thermal and mechanical properties of aggregates and cement paste, presence of sulphates and chlorides in the ingredints of cement etc. This paper presents the durability study of High Strength Concrete (HSC) exposed to aggressive environment. The durability of HSC made with different types of coarse and fine aggregates is studied by immersing in 1 and 5% solutions of NaCl and Na_2SO_4 for different periods. The HSC is made with concrete mix 1:0.8:2.2 with water-cement ratio as 0.30. The desired degree of workability of concrete is obtained at lower water-cement ratio by adding superplasticizer dose @ 2% by weight of cement. The effect of partial replacement of cement by equal amount of flyash and silicafume in varying percentages is also studied in above solutions. Test results indicate that the compressive strength of concrete in 1 and 5% solution of NaCl and Na_2SO_4 decreases slightly upto 28 days. Further, the decrease in compressive strength of HSC with partial replacement of cement by equal amount of flyash, silicafume, flyash and and silicafume in varying percentage after 28 days is less then the decrease in compressive strength of concrete without flyash and silicafume. Thus, from the results of the above investigation it can be concluded that HSC with and without flyash and silicafume can be effectively and economically used in aggressive environmental conditions.