EFFECT OF POZZOLANAS ON BEHAVIOUR OF HPC EXPOSED TO ELEVATED TEMPERATURE

Abstract

The strength and durability performance of high performance pozzolanic concretes incorporating silica fume, fly ash, and blast furnace slag was compared with the same strength (M 60) of Concrete without pozzolanic material at elevated temperatures up to 800°C to study the effect of these pozzolanas on behavior of HPC exposed to elevated temperatures. The temperature ranges were room temperature, 200, 400, and 800°C. The residual mechanical properties such as residual compressive strength, residual split tensile strength, and residual modulus of elasticity were determined using an unstressed residual compressive strength test, while durability was investigated by rapid chloride permeability test and crack pattern observations. It was found that pozzolanic concretes containing blast furnace slag and fly ash give the best performance particularly at or below temperature' 400°C as compared to the pure cement concretes. Explosive spalling occurred in high performance concretes (HPCs) containing fly ash. A distributed network of cracks was observed in all concretes. The high performance concretes showed a severe loss in permeability-related durability than the compressive strength loss.