Microwave Assisted Synthesis and Experimental Exploration of Geopolymer Lightweight Aggregate

Abstract

In recent technological advancement, microwave-assisted technologies have received an increasing attention to substitute traditional curing techniques, mainly because of the major benefit of volumetric heating. This research is mainly focused on the production of artificial LWAs, which meets the present requirement of construction industry, incorporating fly ash (FA) and silica fume (SF) through geopolymerization. In this investigation, alkaline activator, a combination of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) is used as a coagulant. The handcrafted pellets were cured in microwave oven for 5 minutes only. These manufactured LWAs were characterized by determining physical and mechanical properties and compared with natural and synthetic LWAs available in the literature. The experimental tests including morphology, density, porosity, water absorption, crushing strength and aggregate impact value were studied. Test results exhibit that depending on ingredients properties and the curing environment, density of formulated LWAs is 44% less compared to normal weight aggregates and lighter than many previously manufactured cold bonded and sintered LWAs. The evaluation of mechanical properties proved the suitability of microwave cured LWAs. Based on the preliminary findings, proposed technology appears to be a viable solution for the production of eco-friendly LWAs by allowing waste materials to be recycled and energy saving for their production.