Nano-bentonite as a sustainable enhancer for alkali activated nano concrete: Assessing mechanical, microstructural, and sustainable properties

Abstract

The production of Ordinary Portland Cement (OPC) composites contributes significantly to carbon dioxide (CO2) emissions, necessitating a shift towards more environmentally friendly alternatives in the construction sector. This study explores the potential of incorporating Nano Bentonite (nBT) into Fly Ash (FA) and Ground Granulated Blast Furnace Slag (GGBFS) based Alkali Activated Nano Concrete (AANC) to improve both environmental impact and mechanical properties. Various concentrations of nBT (3%, 6%, 9%, 12%, and 15%) were added to the AANC mixtures, denoted as nBTx. The impact of nBT on fresh properties, mechanical strength, and microstructure of AANC was assessed through standard tests including setting time, slump value, ultrasonic pulse velocity (UPV), compressive strength (CS), splitting tensile strength (STS), flexural strength (FS), modulus of elasticity (MOE), and density. Results show that the addition of nBT decreased setting times, though reduced workability, and facilitated the formation of a compact microstructure, leading to improved mechanical properties. Notably, a 6% nBT concentration demonstrated a significant enhancement in CS, STS, FS, and MOE. Microstructural examinations confirmed the efficient distribution of nBT within the AANC matrix, contributing to a solid microstructure with reduced micro cracks and voids. However, challenges such as non-uniform dispersion and potential agglomeration were noted at higher nBT concentrations. Overall, the integration of nBT into AANC presents a promising pathway towards environmentally sustainable construction practices, offering potential energy conservation benefits and enhanced sustainability in the construction industry.

Keywords

• Alkali-activator concrete
• Bentonite
• Geopolymer concrete
• Nano bentonite
• Nano materials
• Sustainability