Investigation into the Properties of Recycled Aggregate Concrete (RAC) Exposed to Fire

Abstract

This work studied the effect of temperature on concrete made from Recycled Aggregates (RA) exposed to fire. The concrete mixes were made of 0%, 10%, 20%, 30%, 40%, 50%, and 100% replacements of normal aggregates with recycled aggregate obtained from the demolished buildings at Challawa Industrial Estate, Kumbotso LGA, Kano State. A water-cement ratio of 0.7 was considered, and concrete batching was done by weight. Fresh concrete workability was measured using a slump test, while compressive, splitting tensile, and flexural strengths were tested for the mechanical behaviour. The results showed that the workability of the recycled aggregate concrete reduces considerably as the amount of recycled aggregate increases. The concrete specimens were cured inside water for 28 days, and then some were subjected to elevated temperatures of 400°C, 800°C, and 1200°C in a furnace. As the temperature increases to 1200°C, the compressive, splitting tensile and flexural strengths for all the percentage replacements reduces considerably. It was found that 40% recycled aggregate replacement level produces the optimum values of compressive, splitting tensile and flexural strengths.