Effects of Lightweight Aggregate Size and Grading on the Residual Strength of Lightweight Geopolymer Concrete Exposed to Elevated Temperature
The lightweight aggregate geopolymer concrete (LWAGC) systems were prepared using a lightweight aggregate (LWA) of different size and grading. The diversity in the LWA size and grading led to various physical properties like oven-dry (OD) density, water absorption and total porosity characteristics for the resultant LWAGCs. These physical properties were significantly affected and controlled thermal behavior of the concretes after exposure to elevated temperature of 800 °C. The results of the mechanical and physical test conducted to the unexposed LWAGCs showed that the OD-density and compressive strength increased as the LWA maximum and minimum size decreased. In contrast, the water absorption and total porosity of the unexposed LWAGC were increased with increasing of the LWA maximum and minimum size. Thus, the lowest OD-density LWAGC possessed the highest water absorption and total porosity which resulted in lowest compressive strength, whereas, it has the minimal strength loss after exposure to the elevated temperature. The water absorption and total porosity of the unexposed LWAGCs were indirectly implies the permeability characteristics of the concretes which is controllers the thermal behavior of the LWAGC at elevated temperatures.