Effects of the different atmospheric steam curing processes on the properties of self-compacting-concrete containing microsilica

In this paper an attempt has been made to study the use of microsilica on the properties of self-compacting-concrete (SCC) such as compressive strength, splitting tensile strength, flexural strength, ultrasonic pulse velocity (UPV) and micro-hardness when exposed to different atmospheric steam curing temperatures. The influence of microsilica as partial replacement of cement on the properties of SCC is investigated. In this study, mixes were prepared with three percentages of microsilica ranging from 5% to 10% and one controlled mixture without microsilica was also prepared for comparison. The specimens of each concrete mixture were heated up to different temperatures (65 degrees C, 70 degrees C and 75 degrees C). The variables included were the temperature effects (65 degrees C, 70 degrees C and 75 degrees C) using Cem I 42.5. SCC mixes enhanced atmospheric steam curing compressive strength ranging from 29.20 to 38.50 MPa, flexural strength ranging from 4.95 to 6.56 MPa and splitting tensile strength ranging from 1.18 to 1.63 MPa. Test results clearly show that there is little improvement in the compressive strength within temperature range of 70 degrees C as compared to 65 and 75 degrees C, although there is little reduction in splitting tensile strength ranging from 65 to 75 degrees C and with the increase in percentage of microsilica. However, the rate of splitting tensile strength and flexural strength was higher than that of the compressive strength at elevated temperatures and with the increase in percentage of microsilica. In this paper, scanning electron microscopic (SEM) observations were also made to explain the observed residual compressive strength increase between 65 degrees C, 70 degrees C and 75 degrees C.