Effect of elevated temperature on the compressive strength of millet husk ash (MHA) concrete

Abstract

This work aims to show the effect of elevated temperature on the residual compressive strength of concrete made with available ordinary Portland Cement, crushed gravel aggregate, sand and millett husk ash (MHA) added as chemical admixture at a percentage of cementitious material. Variables of this study are temperatures and MHA contents that ranges (RT, 200oC, 400oC & 600oC) and (0, 10% & 20%) respectively. The sample were cured in water tanks for 28 days prior to heating. After heating of the samples in the oven to the desired temperatures allowed to cool to the room temperature (RT) and tested for compressive strength. The average of the three readings obtained is used to represent the condition of the experimental text. The study showed that the compressive strength of MHA concrete and normal concrete decreases when exposed to elevated temperature, where the MHA concrete improve in strength at elevated temperature up to 400oC, the normal concrete decrease in strength within the same range. The best potential of the original value at 600oC is at 10% MHA with residual compressive strength of 87% of the pre-heating value.