Innovative use of wet carbon conversion in alkali-activated slag: Improved microstructures and mechanical characteristics

Abstract

Nano-calcium carbonate (nano-CaCO3) has garnered significant attention due to its remarkable efficacy in enhancing the properties and microstructure of concrete. In this study, the wet carbon conversion method was used to synthesize solid nano-CaCO3 from CO2, which was then added to AAS. Subsequently, the compressive strength and resistivity of the AAS mortar were assessed, and the AAS paste underwent microscopic characterization using experimental methods, including X-ray diffraction (XRD) and Fourier-transformed infrared (FTIR), and scanning electron microscope (SEM) et.al. The effects of the nano-CaCO3 on the microstructure, mechanical characteristics, and durability of the AAS were determined. The microscopic analysis results clearly demonstrate that the nano-CaCO3 prepared using this method exerts significant physical and chemical effects, leading to a notable improvement in the compactness of the AAS microstructure. Moreover, the experimental findings provide further confirmation that the addition of nano-CaCO3 results in a substantial enhancement of both the compressive strength and resistivity of AAS mortar, particularly in the early stages. Specifically, the inclusion of 6% nano-calcium carbonate led to a remarkable 29.8% increase in compressive strength at 1 curing day. Furthermore, the analysis of carbon dioxide emissions from AAS reveals that incorporating nano-CaCO3 effectively reduces the carbon footprint associated with AAS. This implies that adopting this approach not only enhances the performance of AAS but also contributes to a reduction in the environmental impact, thus actively promoting sustainable construction and engineering projects.