The Effect of Water Mixing Temperature on Concrete Compressive Strength Containing Different Ratios of Silica Fume

Abstract

This paper presents the experimental study about the effect of water mixing temperature on concrete compressive strength containing different ratios of silica fume by compressive testing of 108 cubes of (150 × 150 × 150) mm dimensions. The parameters were studied; temperature of water mixing, ratio of silica fume and age of test. The specimens were divided into four groups having different temperature of mixing water (20, 40, 60, and 80)° C, each group consisting of three set with different ratio of silica fume (0%, 10%, and 20%), each set having nine cubes tested in a different age (7, 14, and 28 days). In fresh state, the results showed that different water temperatures give different values of slump when the percentage of silica fume is constant, where the slump value decrease by about (2-4) mm for each 20° C increase in temperature. Also, the slump of the concrete decrease about (5-10) mm at each replace 10% from weight of cement by silica fume. In hardened state, the greatest increase in compressive strength obtained at 40° C by about (20-30) % in compared with 20° C and then began to drop slightly at 60° C, but at a temperature of 80° C observed a great decrease in compressive strength. It is also found that as advanced the age of test, compression strength increases but rate of increase fall at high of temperatures due to early curing causing by high temperature of hydration. it was observed in this study when the water temperature increased above 60° C, the presence of SF resulted to decreasing in the concrete strength.