When a normal PCC is subjected to elevated temperatures, the cement system and aggregate suffers a complete loss of mechanical properties and physical integrity.Therefore when a structure has to be subjected to high temperatures, refractory concretes are adopted. Refractory concretes are capable of retaining is physico-mechanical properties within a predetermined limits during prolonged exposure to high temperature. They are prepared by mixing refractory cement (Calcium Aluminate Cement), recycled clay brick aggregate and required amount of water. The broken bricks obtained during the demolition of masonry structures are crushed into square pieces and are added as the coarse aggregates. The mix design was done, concrete was prepared and samples were casted. They were demoulded after 24 hours and cured for 1 day. It was dried in an oven at 110±5°C for 24hours and was then heated from room temperature to 1200°C in a furnace at an increasing rate of 5°C per minute. These concrete blocks were subjected to laboratory testing to obtain true density, bulk density, apparent porosity, true porosity, hot modulus of rupture, modulus of rupture at ambient temperature, linear change after firing and cold crushing strength by following the IS Codal procedures. The concrete is observed to have lower density and higher fire resistance compared to PCC. The thermal resistance of concrete blocks further increases on increasing the percentage of crushed clay brick aggregates.
Volume 11 | 04-Special Issue
Pages: 365-371