COMPRESSIVE STRENGTH OF CONCRETE

Fire exposure destroys concrete structures, and the cooling methods significantly impacts residual strength Rapid cooling, especially with water, may cause additional damage due to thermal shock, yet limited studies compare air- and water- cooling effects. In order to determine which cooling technique best maintains structural integrity, this study will examine how various techniques affect the breaking strength of Grade 30 concrete exposed to temperatures of 200°C, 400°C, and 600°C. This study involves the preparation of Grade 10 concrete specimens, which were cured for 28 days before being subjected to elevated temperatures of 2000C 400C and 600°C in a controlled furnace. After exposure, the specimens were cooled using air and water to compare the effects of each method on compressive strength. The compressive strength of all samples was tested using a compression testing machine, and the results were analyzed through tabular and graphical comparisons to evaluate strength reduction trends. The study revealed that compressive strength decreased with increasing temperature, with watercooled samples experiencing greater strength loss than air-cooled due to rapid thermal shock. At 600°C, Average water-cooled samples record 26.561 N/mm², while air-cooled samples record 28.014 N/mm², confirming that gradual cooling helps to retain more structural integrity. Based on these findings, air cooling is recommended as a safer and more effective method for post- fire concrete recovery. Further research should explore advanced cooling techniques to enhance fire resistance and durability.

The construction industry is increasingly looking for sustainable alternatives to traditional construction materials. PKS is an agricultural waste product and its incorporation into concrete not only reduces waste but also offers potential economic and environmental benefits. This study addresses this concern by investigating the viability of using palm kernel shell (PKS) as a partial replacement for coarse aggregate in concrete. To evaluate its effect, we conducted a series of experiments in which we replaced conventional coarse aggregate with PKS at varying percentages (0%, 5%, 10%, 15% and 20%). To ascertain how PKS presence affected this crucial attribute, tests were conducted on the compressive strength of the resultant concrete specimens. Cement, sand, coarse aggregate, and palm kernel shell are the materials used. Concrete cubes of 100 mm by 100 mm by 100 mm were formed using a 1:1.5:4 (C30) concrete mix ratio, which was batched by weight. The cubes were crushed after 3, 7, 14, and 28 days to compare the strength at (0%, 5%, 10%, 15% and 20%) PKS replacement According to this research, the results showed that as the percentage of palm kernel shell in concrete increases, the compressive strength decreases alongside its cost and the weight of concrete. At around 10% partial replacement of coarse aggregate with palm kernel shell in concrete gives a significant decrease in cost and weight of the concrete without much affecting the compressive strength of concrete.