Performance of recycled aggregate concrete containing silica fume at elevated temperatures

This study is undertaken to address the environmental problems associated with the large-scale concrete production. To prevent the natural stone reserves, 50% of the recycled concrete aggregate (RCA) are used. Since, the cement used in concrete is responsible for huge CO2 emissions, 10% of its weight is replaced by silica fume. Silica fume improves the properties of recycled aggregate concrete (RAC) by its excellent filling and pozzolanic properties. The compressive and split-tensile strength of the concrete so formed are investigated at room temperature (20°C) as well as elevated temperatures up to 800°C and compared with a reference concrete mix not containing silica fume. It has been observed that silica fume has a beneficial effect upon the compressive as well as split-tensile strength at all exposure temperatures. With the addition of silica fume, an increment of 3.6-14.9% in compressive strength, and 10.9-22.5% in split-tensile strength is found over a temperature range of 20-800°C.