Effect of Admixture on Fire Resistance of Ordinary Portland Cement Concrete

Abstract

Ordinary Portland Cement (OPC) Concrete deteriorates considerably when exposed to aggressive environment such as fire or elevated temperatures. The addition of certain materials obtained from agricultural and industrial wastes to OPC concrete could improve its performance in this environment. This paper investigated the effect of Carbide Waste (CW) on the compressive strength of concrete when exposed to fire. This was achieved by partially replacing OPC with 5, 10, 15 and 20 percent (%) of CW to produce 150 x 150 x 150mm concrete cubes. Sample of 100% OPC were also produced and served as the control. The quantities of cement, fine aggregate and coarse aggregate used for the production of concrete specimens were obtained through absolute volume method of mix design. Water/cement (w/c) ratio of 0.65 was adopted for OPC/CW concrete and the control. For the purpose of the research, Ninety (90) concrete cubes were produced for the two specimens. The specimens produced were cured in ordinary water for 28 days after which they were heated in a furnace at varying temperatures of 200, 300, 400, 600, and 800^oC. Specimens were heated for 2 hours at each testing temperature to achieve the thermal steady state after which their compressive strengths were determined. Increase in compressive strength was observed in the control specimen up to 300^oC after which the specimen suffered severe loss with further increase in temperatures up to 800^oC. However, the compressive strength of CW concretes increases with increase in temperature up to 500^oC and then, decreases with further increase in temperatures. 10% replacement of OPC with CW performs satisfactorily better than other replacement level at all temperatures. Replacement of OPC by 10% CW increases concrete resistance to fire by 14% of OPC concrete.

Keywords: Blended Cement, Carbide, Concrete, Fire and Performance.