Properties of concrete at elevated temperatures using selected brands of ordinary Portland Cement
In recent times, there has been a serious controversy as to whether the different brands of OPC commonly used in Nigeria can attain adequate strength and even the Standard Organization of Nigeria (SON) attributed the incidences of building collapse in the country to this assumption. This has prompted researchers to investigate the properties of concrete produced with various brands of the cement produced in the country. This study therefore evaluates the properties of concrete made with different Nigerian brands of OPC exposed to an elevated temperature. Four brands of Ordinary Portland Cement commonly available in Nigeria were used in this project to produce different concrete specimens which were labeled A, B, C and D. a total of seventy two (72) specimens of size 100mm x 100mm x 100mm cubes were produced using a nominal mix of 1:2:4 and W/C ratio of 0.55. After curing the concrete specimens produced in water for 28days, 36 of the specimens were exposed to an elevated temperature of 800oC, 1000oC and 1200oC for 3hrs while the remaining 36 were used as control. Thereafter, compressive strength of the concrete specimens was determined. The average compressive strength obtained for concrete specimen made with cement brand A, B, C and D exposed to 800oC were 6.27N/mm2, 5.08N/mm2, 5N/mm2 and 6.4N/mm2 respectively while at 1000oC the compressive strength values were 3.03N/mm2, 1.97N/mm2, 2.57N/mm2, and 3.27N/mm2 respectively. At 1200oC, all the concrete specimens melted. Result obtained shows that concrete specimen produced with cement brand D has better compressive strengths when compared to A, B and C. It is concluded that cement D showed higher compressive strength after its exposure to elevated temperature. It is therefore recommends that cement D be used in areas where concrete is likely to be exposed to high elevated temperature.
Keywords: Brands of Cement, Elevated Temperature, Properties, Compressive Strength