Optimization of eco-friendly materials by alkali activation of the sewage sludge ash (SSA) to reduce carbon footprint

Abstract

ABSTRACT To address climate change and promote sustainable development in the building materials industry, this study aimed to develop eco-friendly geopolymer products to replace the high carbon footprint cement industry. The study evaluated the production of geopolymer by partially substituting slag with sewage sludge ash (SSA) and testing different alkaline activator ratios. The ratio of GGBS to SSA was 70:20% by weight, and Na2SiO3 and NaOH were the utilized activators with varying percentages by weight. The geopolymer pastes were cured by using a thermal bath with a temperature of 38°C at 100% relative humidity in a controlled humidity chamber for 3 months. The chemical composition, the mechanical strength at specific testing times, and the microstructure of the materials and the pastes have been analyzed through XRD, XRF, FTIR and SEM. The valuable results have been achieved at a ratio of (10:10%) Na2SiO3 to NaOH, with a strength of 285.6 kg/cm2 at 90 days. XRD and FTIR of the mix A1 showed the formation of amorphous phases of geopolymer gel. Also, a dense microstructure was observed in the SEM micrograph of the mix A1. Consequently, the study results demonstrated that sewage sludge ash can be reused as a value-added product through the potential use in the synthesis of geopolymer products with an optimum alkaline activator of (10:10%) sodium silicate to sodium hydroxide. SSA – geopolymer products will help in the reduction of the carbon footprint and maintain the natural resources in addition to the achievement of climate goals.