Behavior of alkali-activated pozzocrete-fly ash paste modified with ceramic tile waste against elevated temperatures and seawater attacks

Abstract

Huge quantities of ceramic tile waste are disposed annually in an unsafe manner, causing some environmental problems including air and soil contamination. So the re-use of such waste would be the perfect solution to get rid of these problems. This research focused on exploring durable and thermal stable geopolymer-based alkaline activation of pozzocrete-fly ash (PFA) doped with different ratios of ceramic tile waste (CW) compared to their plain mixtures under normal conditions. The PFA waste was modified upon partially replaced with the CW waste at replacement levels of 0%, 5%, 10%, 15% and 20%, by weight. All PFA-CW pastes activated with a mixture of NaOH and Na2SiO3 solutions. The hardened specimens were cured in 100% RH at 40 ± 2 °C for 1, 7, 14 and 28 days. After 28 days, some specimens were exposed to elevated temperatures of 200 °C, 400 °C, 600 °C and 1000 °C with a heating rate of 5 °C/min. Another batch of specimens were subjected to seawater for 1, 3 and 6 months. The mechanical properties as well as microstructure analysis prior and after exposure were monitored. The geopolymer phases were examined by Fourier transform infrared spectroscopy (FT-IR), Thermogravimetric analysis plus its derivative (TGA/DTG) and Scanning electron microscopy (SEM). The findings indicated that the CW waste has a positive effect on the properties of PFA-geopolymer. The inclusion of 10% CW enhanced the properties in terms of compressive strength and microstructure before and after exposure to high-temperature and seawater solution.