Effect of Microsilica Additive on Compressive Strength and Water Absorption of Lightweight Concrete

Concerning the issue of the seismicity of Iran and the effect of structure weight on the amount of earthquake load exerted on the structure, there is the need for stylization of structures in order to reduce the costs of designing and repairing structures against earthquakes. It is possible to build structural light-weight concrete by using different additive materials. Microsilica is of the additives of concrete, which is of a significant role in improving concrete characteristics. In this paper, as regards to the positive influence that the additive material puts on the concrete compressive strength, it has been used as a replacement of a part of the cement used in the concrete mix design. Investigation of the compressive strength of light-weight concrete with microsilica contents of 4, 8, and 12 weight percentage of cement at the ages of 28, 118, and 148 days and the water absorption of 90-day samples have been performed through experimental study. It was observed by investigating the compressive strength and the obtained results that using microsilica up to 12% leads to increase compressive strength relative to the control sample. The optimal amount of the used microsilica at all ages is equal to 8% of cement weight. In addition, by increasing of the consumable microsilica up to 12%, the concrete water absorption is reduced as compared to the control sample, and finally causes to reduce the porosity of the light-weight concrete. All the experiments during this study have been performed at the concrete laboratory of the civil engineering faculty of Islamic Azad University, Najaf Abad Branch.