Effect of CO2 curing on the strength and microstructure of composite waste glass concrete

Given the bottleneck issue of reduced concrete strength caused by the substitution of glass sand and glass powder, this paper proposes CO2 curing for composite waste glass concrete (CGC). The study focuses on investigating the effects of CO2 curing on the mechanical properties and microstructure of CGC. The carbonation mechanism of waste glass concrete was elucidated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and low-field nuclear magnetic resonance (NMR). The results indicate that the high initial porosity and metallic cations in CGC promote the carbonation rate, effectively addressing the slow strength development of concrete. After 7 days, the compressive strength of the concrete improved by 25.87 %. The addition of waste glass increased the volume of transition pores and capillary pores in the concrete,but the larger interfacial pores provided a harmless space for calcium carbonate precipitation, mitigating the coarsening of the concrete pore structure. Furthermore, the synergistic effect of low-carbon recycled glass materials and CO2 curing can reduce the carbon footprint of concrete while meeting strength requirements, with a maximum reduction of up to 15.50 %. This research has important theoretical and practical significance for achieving carbon reduction and low-carbon transformation in the construction field.