Multicriteria analysis for quantifying sustainability of developed load bearing lightweight geopolymer

Abstract

In geopolymers, several factors such as the limited availability of amorphous aluminosilicate material, the need for a high dosage of activator, the requirement for hot curing conditions, and the activation by pressure pose challenges in considering geopolymer as a sustainable load-bearing material. Therefore, this experimental and analytical work aimed to address the aforementioned issues. The experimental work was carried out in four distinct series, where fly ash (FA) was combined with sugarcane bagasse ash (SCBA), slag (GGBS), and lime. The alkaline to precursor (A/P) ratio and curing conditions were varied. Initially, the compression casting approach was employed to reduce the dosage of activator. But later on, lime was added to prevent such a technique, and the alkaline dosage was reduced due to occupying effect. Thereafter, three key performance indices of sustainability were quantified: load-bearing lightweight (Dp), environment (Ep), and economic (Cp). These indices were determined by normalizing density, CO2 emissions, and cost by compressive strength, respectively. It was observed that FA-lime-based mortar is a sustainable geopolymer. It is ambiently cured and has the least alkaline activator, high strength, minimal CO2 emissions, and low cost. It was also compared to conventional construction materials such as fired clay brick and concrete, and promising results were obtained. Sustainable quantification was conducted analytically by extracting seven alternatives from four series and analyzing a 7 × 7 decision matrix using the multicriteria decision-making technique. The FA-lime-based specimen was selected experimentally and verified analytically, along with a prioritized list of all specimens.