Effect of Saw Dust ash (SDA) Pozzolana on the Performance of Blended Cement Paste Concrete at High Temperatures

Abstract

This study is aim at investigating the thermal stability of concrete paste blended with ordinary Portland cement and saw dust ash (OPC/SDA). The SDA is thermally activated at 800oC for 2 hours and the concrete pastes prepared with constant consistency. The pastes were kept in moulds at room temperature and 100% relative humidity for 24 hours and then hydrated for 28 days under water. The hydrated concrete pastes were exposed for 2 hours to temperatures of 200, 400, 600, and 800oC. The hydrated concrete specimens were tested for compressive strength and thermal shock stability after heat treatment. It was found that, the compressive strength of the control cement paste concrete increase up to 400oC and suffers a more loss of compressive strength as the treatment temperatures were increased. However, the blended cement paste concrete experience an increase in compressive strength with temperature up to 600oC and then, the strength decrease as the treatment temperature was increased up to 800oC. The replacement of OPC with 10% SDA in the blended cement paste concrete increases the thermal shock resistance by about 4 times that of the control cement paste concrete. Blending of OPC with about 10% of SDA in concrete can improve on its thermal stability and durability.

Keywords: Blended Cement, Cement Paste, Concrete, Performance, Saw Dust Ash (SDA), Temperature.