Behaviour of Expanded Flyash Clay Aggregate Concrete Exposed to Elevated Temperature

Expanded flyash clay aggregate (EFCA) is a promising sustainable alternative to coarse aggregate in concrete. Concrete specimens with conventional natural aggregate and EFCA as coarse aggregates were prepared separately and exposed to elevated temperatures of range 200°C, 400°C, 600°C and 800°C, observed for surface changes like change in color and formation of visual cracks, tested for loss in mass, strength and water absorption, analyzed by XRD for mineralogical changes through variation in chemical composition. Specimens when exposed up to 400°C has not shown any notable changes in the above property, beyond which strength of both specimens started to decrease gradually, at higher temperature EFCA mix showed loss in mass of 4.5% compared with normal concrete, visual observation of specimen surface showed EFCA specimens sustained cracks till 600°C. EFCA mix also showed a constant rate of water absorption. Concrete with EFCA showed consistently higher compressive strength at higher temperature up to 400°C and found satisfactory in all aspects tested made EFCA as coarse aggregate in concrete as a sustainable alternative to natural aggregates.