A comprehensive assessment of sustainable high-strength hybrid geopolymer concrete

Abstract

This study focuses on the production and evaluation of high-strength hybrid geopolymer concrete (HSHGC), an innovative substitute for conventional slag-based geopolymer concrete. The proposed concrete incorporates a range of waste materials, such as charcoal ash, brick waste, fly ash, granite powder, dolomite powder, rice husk ash, and glass waste, as partial replacements for slag. This approach is designed to address critical environmental challenges by reducing landfill accumulation, minimizing greenhouse gas emissions, and lowering production costs, thereby contributing to global sustainability goals such as the sustainable development goals and green concrete initiatives. A total of ten HSHGC mixes were developed, utilizing three different waste materials in each mix to partially replace slag. Key experimental parameters investigated include binder ratios (20% and 40%), mixing procedures, and curing methods (heat, water, and steam + water). A comprehensive suite of physical, mechanical, and durability tests was conducted, including assessments of workability, compressive strength, tensile strength, flexural strength, shrinkage, porosity, pulse velocity, sorptivity, and resistance to sulfate attack. Additionally, the sustainability performance of the HSHGC was evaluated in terms of cost-efficiency, energy efficiency, and carbon efficiency. The results confirmed that HSHGC is a viable and sustainable alternative to traditional slag-based geopolymer concrete, exhibiting comparable or superior mechanical and durability properties. Specifically, steam + water curing was identified as the most effective curing method, significantly enhancing compressive strength. In terms of workability, increases of 38.5 %, 46 %, 54 %, 23 %, and 27 % were observed in the M₀-CA, FA20, FA40, GP20, and DP20 mixtures, respectively. Moreover, the compressive strength of the FA20 and FA40 mixtures increased by 15.4 % and 12.8 %, respectively. Shrinkage was reduced by 19.2 % in the FA40 mixture and 25 % in the GW20 mixture, resulting in enhanced long-term stability and performance. Notably, the RHA20 mix, despite having lower initial strength, exhibited superior resistance to sulfate attack, making it particularly suitable for applications in coastal and saline environments. Furthermore, in terms of environmental efficiency, the M₀-CA mix demonstrated a 1.3 % improvement. They also showed reductions in carbon emissions, energy consumption, and costs in all mixtures. This research underscores the significant potential of HSHGC as a transformative material in construction, aligning with global sustainability goals and addressing modern construction demands.