Mechanical Performance of Steam-Cured Self-Compacting Concrete Incorporating Silica Fume and Limestone Powder

Abstract

In this paper, influence of heat treatment on evolution of mechanical strengths at early age, less than 24hours of self-compacting concretes containing limestone powder and silica fume as fine materials was investigated experimentally. Two compositions of self-compacting concrete have been studied; the first is elaborated with silica fume addition and the second with limestone powder, each mixture were prepared with a constant water/binder ratio of 0.39. Concrete samples were either cured in water at (23±1°C), or steam cured at 65°C maximum temperature over six hours (6h) curing period. Tests of mechanical strengths were performed on specimens cooled down slowly to room temperature after heating.The obtained results show that all self-compacting mixtures exhibited satisfying fresh properties and check EFNARC specifications of self-compacting concrete (slump flow diameter higher than 650mm, L-box ratio higher than 80% and sieve stability less than 17%).Mechanical strengths of concrete containing limestone addition are slightly lower than those of concrete based on silica fume at all ages. Moreover, heat treatment generates an improvement of compressive and flexural strength. Interesting compressive strengths are obtained. At 24 hours, after heat treatment, the strengths are already greater than 35 MPa. The values ​​are 37 MPa and 40 MPa for self-compacting concrete containing limestone powder and silica fume respectively compared to 40 MPa and 46 MPa obtained at 7 days for the corresponding non-heat treated concretes. Compressive strength gain of SCCs mixtures with limestone powder and with silica fume, undergoing heat treatment at the age of 24hours is 85% and 75% respectively compared to SCCs mixtures cured in water.