Effect of elevated temperature on physico-mechanical properties of blended cement concrete

Abstract

Pozzolanas are readily available for use in concrete in the local markets for strength and/or durability enhancement. Although safety and security against disasters are not new, they still presuming a challenge. For instance, the fire resistive properties of concrete are of prime interest. Through this work, the effect of different kinds of pozzolana on the fire resistive properties of concrete was studied. Four types of pozzolana were incorporated into the concrete mixtures, i.e. metakaolin (MK), silica fume (SF), fly ash (FA), and ground granulated blast furnace slag (GGBS). Each of the employed pozzolana was used in two ratios: 10% and 20%, either in the form of cement replacement or as an addition without affecting the cement content. A total of 17 mixes were cast. For all mixtures, compressive strength is evaluated after 28 days of water curing. The mixtures’ compressive strengths were also evaluated after exposure to elevated temperatures: 200 °C, 400 °C, 600 °C, and 800 °C. The residual compressive strengths after heat exposure are evaluated. The formed cementitious phases after incorporation of pozzolana and the heat-induced transformations are investigated via the X-ray diffraction technique (XRD). Test results demonstrate the impact of each type of the employed pozzolana on the heat resistive properties of concrete in addition to their influence on the strength development of the investigated mixes. Therefore, a decision could be made regarding optimizing the benefits specific to each type of pozzolana and their employment method.