Optimizing the accelerated hardening of sawdust light weight concrete with carbon dioxide gas

Abstract

Recent increases in the amount of industrial wastes to be removed has made dealing with such waste products and gases an issue that needs to be solved with some urgency. The accelerated hardening mechanisms of light weight concrete (LWC) using carbon dioxide gas were thus studied in an experimental study to investigate the mechanical performance of concrete incorporating waste sawdust. The final results were optimised to maximise strength and minimise density using two different parameters: gas concentrations and sawdust percentages. All samples were subjected to tests of their mechanical and physical properties, including compressive strength, splitting tensile strength, water absorption, and density using the relevant standards. Parts of the samples were also submitted to thermogravimetric analysis (TGA) following the process of accelerated curing in order to quantify the consumed calcium hydroxide (Ca(OH) 2 ) and the produced calcium carbonate (CaCO 3 ). The results of the study showed an improvement in the physical and mechanical properties of all investigated specimens using the accelerated CO 2 curing method. In addition, a 7% sawdust addition with 53% CO 2 concentration resulted in higher strength in all cases. The TGA results proved that the carbonation curing resulted in lower Ca(OH) 2 and higher CaCO 3 content, with associated enhancement in the mechanical performance. This indicates that CO 2 -rich industrial emissions could find a value adding use in carbonation curing of sustainable wood-based concrete.