Mechanical Properties of Lightweight Oil Palm Geopolymer Concrete under Elevated Temperature

The purpose of this study is to investigate the effect of high temperatures on the mechanical properties of lightweight geopolymer concrete made of palm oil industrial waste materials known as palm oil fuel ash (POFA) and oil palm shell (OPS) as binder and coarse aggregate in geopolymer concrete would give an added advantage in both environmental and economic aspects with alkaline activator to binder (AK/B) ratios of 0.3 and 0.6. For each (AK/B) ratio, POFA was replaced with 0%, 10%, 25%, 50%, and 100% of fly ash (FA). To that purpose, the mechanical properties of OPS geopolymer concrete (OPSGC) produced using POFA, FA, and OPS are examined in terms of compressive strength, splitting tensile, and flexural strength. To determine the compressive strength loss for each mixture, the geopolymer concrete samples were subjected to high temperatures of 200°C, 400°C, 600°C, and 800°C. The test findings showed that increasing the alkaline activator to binder (AK/B) ratio at 3, 7, and 28 days increased the compressive strength. Generally speaking, exposure to temperatures above 200°C causes the OPSGC to increase in compressive strength. Following exposure to temperatures as high as 400 °C, the OPSGC’s strength began to decline. AK/B ratio of 60 are less affected by high temperatures than mixes made with an AK/B ratio of 30. The miture of 25% POFA content, AK/B ratio of 0.6, and oven curing provided the maximum strength of 30.9 MPa and Less strength loss compared to other options.