Experimental investigation on autogenous shrinkage of high and ultra-high strength concrete

Abstract

Recent trends in concrete technology have been towards high-strength concrete and ultra-high strength concrete with a low water-cement ratio. However, these high and ultra-high strength concretes have some problems. One of the problems is early-age cracking due to autogenous shrinkage. This study presents the results of an experimental investigation carried out to evaluate the autogenous shrinkage of high and ultra-high strength concrete. Main ideas on autogenous shrinkage are based on the use of ordinary Portland cement, but it has already become apparent that mineral admixtures and fibers change the behavior significantly. Variables were taken to study its effect on shrinkage like (effects of water/cement ratio, cement content, coarse aggregate content, silica fume percentage and steel fiber). From the test results, it is concluded that the autogenous shrinkage strain of mixes increases with decrease w/c ratio and decrease with increasing w/c ratio and concrete with the higher value of cement content, shows greater amounts of shrinkage. The autogenous shrinkage strain increases with decreasing of the coarse aggregate content. The additions of 10-20 % of silica fume to the mix increase the autogenous shrinkage strains of concrete specimens. The autogenous shrinkage decreased gradually with the increase of steel fiber content.