Effect of high temperatures on the properties of lightweight geopolymer concrete based fly ash and glass powder mixtures

Given the large manufacturing and consumption of concrete globally, there has been widespread speculation that it is a significant source of greenhouse gas emissions. Consequently, scientists are looking for sustainable and beneficial solutions to the environment. The influence of adding expanded clays (Leca) and crushed recycled bricks clay lightweight aggregates (RBA) on the fly ash and glass powder-based geopolymer concrete were investigated at ambient and high temperatures. High temperature influences the significant characteristics of mortar and lightweight aggregate geopolymer concrete. Low calcium fly ash was utilized as a binder in the concrete paste with a 10% replacement rate of Glass Powder. The concrete specimens were heated to 200, 400, 550, and 800 °C at a 7 °C/min rate for 60 min. Lower coarse aggregate strength is a contributing factor to concrete compressive strength reductions. The influences of high temperatures on geopolymer concrete were studied in terms of mass loss, cracking, water absorption, and microstructure. The research outcomes show that the geopolymer concrete suffered damage and dehydration at a heating temperature of 550 °C and above. Acceptable correlation between the temperature degree and Ultrasonic Pulse Velocity UPV with the compressive strength of the lightweight concrete. The test results showed the residual compressive strength 110.2%, 92.9%, 71.9%, and 55.6% as well as 109.2%, 91.5%, 79.6%, and 52.6% in addition to the density reduced 0.17%, 2.56%, 7.29%, and 12.18%, and 0.74%, 3.97%, 6.31%, and 13.25% in 200,400,550, and 800 °C for Leca and RBA type respectively. The equations showed acceptable results with experimental data. The impact of replacing waste glass powder with fly ash on the development of microstructures and gels was also investigated.