Effect of high temperature on physical, mechanical and microstructure properties of alkali-activated slag pastes blended with ceramic waste material

Abstract

This paper presents the influence of ceramic waste powder (CWP) inclusion on the physico-mechanical properties and microstructure analysis of alkali-activated pastes prior and after exposure to elevated temperatures. Such geopolymer specimens were designed upon replacing ground granulated blast-furnace slag (GGBFS) with CWP at ratios of 0%, 5%, 10%, 15% and 20%, by mass. The water absorption and compressive strength (wet and dry) of non-exposed samples were determined at curing ages of 1, 7, 14 and 28 days. After that, the specimens were exposed to high temperatures of 200, 400, 600 and 1000 °C with a heating rate of 5 °C/min. The characteristics of tested samples such as visual inspection, residual compressive strength and microstructure were evaluated. Techniques as Fourier Transform Infrared spectroscopy (FTIR), Thermogravimetric Analysis (TGA/DTG) and Scanning Electron Microscopy (SEM) were used for studying molecular and microstructure of geopolymer composite. Results indicated that the inclusion of CWP with slag in composite structure based geopolymer enhanced the physico-mechanical properties and microstructure of mixtures before and after thermal exposure. The specimens made of 15% CWP displayed superior thermal stability in terms of remaining compressive strength and microstructure than the reference ones.