The Mechanical Studies of Special Concrete with Pozzolan Subjected to Elevated Temperatures

Abstract

Concrete is a fundamental building material, but its performance under high temperatures raises concerns about structural safety and resistance, particularly in fire scenarios. Standard concrete experiences significant strength and integrity loss or compromise when exposed to elevated temperatures. This is a critical concern for structures like chimneys, industrial facilities, bakeries and fire-resistant buildings. Traditional concrete experiences a decline in strength, cracking, and spalling (flaking) upon heating. Sand and pozzolan samples were collected from Wum, Menchum Division in the North West Region of Cameroon and were analysed using standard methods, according to the Cameroonian prescribed standards. The plain concrete was mixed with sand, gravel and normal Portland cement CIMAF 42.5R. The concrete was then stabilised with pozzolan as a partial replacement for sand. For the partial replacement, 10% and 20% were used. Curing was done for 7days, 14days and 28days and later subjected to controlled temperatures of 20℃, 120℃, 250℃ and 300℃, before crushing. The compressive strength showed that concrete of 20% pozzolan in the partial replacement of sand gives a compressive strength of 25.67MPa when subjected to a temperature of 300℃ after 28days of curing. Also, as the temperature increased from 250℃ to 300℃, the compressive strength of concrete increased, which can be explained by the fact that pozzolan is a volcanic ash and is formed under extreme temperature and thus has fire resistance properties, due to high temperature stability. Concrete made with 20% pozzolan replacement with the strength of 23MPa at room temperature and 25.67Mpa at elevated temperature of 300℃ can be used for all structural elements with the same specifications but higher resistance to fire and elevated temperatures. Pozzolan in small percentages can be very good for fire-resistant structures like chimneys, fireways, and local baking ovens.