Synthesis and Performance of Lightweight Geopolymer Concrete

Abstract

A lightweight concrete (LWC) displays physical, mechanical and structural features preferred in contemporary concrete industry. A major synthetic method for manufacturing high-performance LWCs is to use fly ash-based lightweight aggregates (FA-LWAs). However, the high-powered FA-L.WA manufacture, in combination with the mounting criticism to the high CO₂ emission of cement industry, will bring in problems of energy consumption, production cost and ecological and environmental defects, and therefore hinder the promotion of high-performance LWCs in current concrete market. For this case, this research investigated a LWC synthesis which consumed less energy but still possessed the desired features, by exploring the employment of a fly ash-derived geopolymer technology capable of generating lightweight and high-strength materials under mild-temperature conditions. An in-depth investigation on the mechanism of geopolymerisation, including the aspects of raw materials, mix design, and curing temperature, moisture and curing period conditions, was conducted based on mechanical and chemical techniques for synthesizing desired geopolymer materials. Then, the synthetic procedures for LWCs, which consumed less energy compared to the traditional ones, were researched and utilised. The LWCs using both OPC-based and geopolymer binder-based cementitious systems were considered. The physical, mechanical and microstructural performance of produced LWCs was later evaluated, which indicated that these LWCs were of sufficient qualities for high- or medium-strength structural applications. These outcomes confirmed the possibility of producing a low-cost, eco-friendly structural LWC based on the geopolymer technology proposed in this research.