Statistical Analysis of the Effect of Exposure to High Temperatures on Compressive Strength of Metakaolin Concrete

Using metakaolin as a mineral additive in concrete by replacing cement improves concrete strength due to its pozzolanic activity. It was observed by earlier researchers that the research centered around low- and medium-grade Metakaolin concretes. Also, the range of temperatures to which Metakaolin is exposed to study the fire effect is narrow. This research aims to study the effect of replacing cement with various percentages of Metakaolin in low, medium, and high-strength concretes on compressive strength and fire resistance. The range of grades considered for the study is M20 to M40, with increments of 10 MPa. The percentages of cement replacement with metakaolin are 0%, 10%, 15%, 20%, 25% and 30%. The range of temperatures considered in this study is 100°C, 200°C, 300°C, 400°C and 500°C for the durations of 1, 2 and 3 hours. It was concluded from the study that the maximum improvement in the strength of concrete in compression is 11.68% for M80 concrete, with cement replaced by 15% Metakaolin at 28 days of curing for the control specimen (0% Metakaolin at 27oC curing). The maximum compressive strength obtained for ordinary cement concrete exposed to 1000C for 1 hour, 2 hours and 3 hours is 86.67 N/mm2, 89.33 N/mm2, 88.22 N/mm2 for M80 grade. However, the same is true for concrete with 15 % cement replacement by Metakaolin, obtained as 100 N/mm2, 102.22 N/mm2, and 99.11 N/mm2, respectively.