ADVANCING ECO-FRIENDLY CONCRETE: EVALUATING THE IMPACT OF WASTE GLASS POWDER AS A SUPPLEMENTARY CEMENTITIOUS MATERIAL

Abstract

The growing global need for concrete drives significant CO2 emissions, which motivates the partial replacement of cement with supplementary cementitious materials (SCMs). Concurrently, the disposal of waste glass presents a pressing environmental challenge due to its non-biodegradable nature and its consumption of valuable landfill space. This study evaluates waste glass powder (WGP) as a sustainable SCM in concrete. In the first experimental phase, the pozzolanic reactivity of three glass powder (GP) types: window glass (WG), bottle glass (BG), and materials-recovery-facility glass (MRF) as well as fly ash (FA) was assessed. This was done using the Strength Activity Index (SAI), a modified lime strength test, X-ray diffraction (XRD), and thermogravimetric analysis (TGA) to quantify hydration. WG and BG achieved satisfactory SAI performance at approximately 20% replacement, while higher dosages reduced mechanical performance. The degree of hydration showed that WG and FA delayed early hydration but substantially improved hydration at a later stage. These hydration results correlated well with mechanical performance. The second experimental phase quantified the interactions of cement content, w/c ratio, and replacement level using a Taguchi approach. Each factor had three levels, and the compressive strength, workability, and sorptivity were assessed. The replacement rate had the most significant negative impact on strength, while the w/c ratio was the most influential factor for both workability and sorptivity. Based on these experimental results, predictive models using multiple linear regression (MLR) were developed and validated against test data. The alkali-silica reaction (ASR) was also evaluated for WG and BG to determine their potential for expansion. ASR expansion was reduced by more than 50% at GP replacements of 20–60% relative to controls.