Combined effect of high temperature and silica fume on the Ph and some mechanical properties of concrete.

This research studied the effect of high temperature and silica fume as a replacement material in concrete. Compressive strength, tensile strength and flexural strength were studied. All specimens were studied at 23c° and three high temperatures (150c°,350c° and 550c°). Results showed that drop in hardened properties decreased with increasing temperature as silica fume replacing ratio increase. Optimum replacing ratio was about 30% resulted in the best hardened properties of concrete. As age progress for concrete from 7 days to 90 days drop in hardening properties reduced gradually. Finally, results showed that pH slight deceasing in age (1, 7, 28 and 90) days for all temperatures. [ABSTRACT FROM AUTHOR]