Correlating Experimental and Predictive Method for Compressive Strength of Concrete with Temperature Effects

摘要

This study assessed the effects of elevated temperature on the compressive strength of concrete to determine the strength of concrete after fire outbreak. Two assessments were done which include; using laboratory experimental tests and using a mathematical model. The concrete grade of 25N/mm~2 with design mix of 1:1.5:3 and w/c of 0.56 were used. A total of 21 concrete cubes (150mm x 150mm x 150mm) were cast. After 24hrs, the cubes were de-moulded and cured in water at ambient temperature in the laboratory for 28 days. At 28 days age, the cubes were removed from the curing tank and air-dried for 2hrs before being subjected to these sustained elevated temperatures: 28°C, 50°C, 100°C, 150°C, 200°C, 300°C and 400°C for 1 hour. Thereafter their compressive strengths were determined. A Non-linear regression model was developed to predict the compressive strength of the cubic concrete specimen after oven heating. The model adequately predicted the compressive strength of concrete at given temperatures and weight after oven heating with a correlation coefficient of 0.81.