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Lightweight aggregate concrete, known for its light weight, thermal insulation, and excellent durability, has garnered significant attention and is considered an ideal material for lightweight ultra-high-performance concrete. Previous research has discovered that prewetting lightweight aggregates can continuously release water during the setting and hardening process of concrete, providing internal curing. However, the moisture release behavior of prewetted lightweight aggregates under different temperature and humidity conditions, as well as their internal curing mechanisms in low water–cement ratio mixtures, remains unclear and requires further investigation. In response to environmental sustainability, this study utilizes industrial waste γ-C2S to produce a high-strength carbonized γ-C2S lightweight aggregate (CC) and primarily compares the water absorption and release characteristics of three different types of lightweight aggregates, focusing on the influence of curing temperature and humidity on the water release behavior of the prewetted CC and establishing a water release model for the prewetted CC in cement-based materials. The experimental results indicate that the water absorption rates of the self-made high-performance lightweight aggregate (CC), magnesian lightweight aggregate (MC), and shale lightweight aggregate (SC) conform to the typical Boxlucas equation. In an air environment, the CC has the longest water release duration, followed by the MC, with the SC being the fastest. The water storage performance of the prewetted SC was poor, while the 100% prewetted CC exhibited better water storage during the mixing stage. When the CC is 100% prewetted, it can significantly increase the free water content in the interfacial transition zone, aiding in the hydration of the interfacial transition zone and enhancing the efficiency of shrinkage compensation by the expansive agent. This improvement contributes to the mechanical strength and volumetric stability of cement-based materials. [ABSTRACT FROM AUTHOR]

The study of the mechanisms affecting the preparation parameters of carbonated steel slag is of great significance for the development of carbon sequestration materials. In order to elucidate the mechanism of the influence of moisture on CO2 diffusion and particle cementation in steel slag, the effects of different water–solid ratios and water contents on the mechanical properties, carbonation products, and pore structure of steel slag after carbonation were investigated. The results show that increasing the water–solid ratio of steel slag can control the larger initial porosity and improve the carbon sequestration capacity of steel slag, but it will reduce the mechanical properties. The carbonation process relies on pores for CO2 diffusion and also requires a certain level of moisture for Ca2+ dissolution and diffusion. Increasing the water content enhances particle cementation and carbonation capacity in steel slag specimens; however, excessive water hinders CO2 diffusion. Reducing the water content can increase the carbonation depth but may compromise gelling and carbon sequestration ability. Therefore, achieving a balance is crucial in controlling the water content. The compressive strength of the steel slag with suitable moisture and initial porosity can reach 118.7 MPa, and 217.2 kg CO2 eq./t steel slag can be sequestered. [ABSTRACT FROM AUTHOR]

The porous anorthite ceramics with high porosity, good mechanical strength and low heat conductivity were prepared using red mud and fly ash as raw materials via the pore forming method. The effects of sintering temperature and fly ash on phase evolution, densification, compressive strength, thermal conductivity and microstructure of the ceramic materials were investigated. The results showed that the compressive strength of the porous ceramics had an obvious improvement with the increase in fly ash, and the densification and heat conductivity decreased firstly and then increased. In particular, specimen S2 containing 30 wt% red mud and 40 wt% fly ash sintered at 1150°C had the better performances. It had the water absorption of 18.18%, open porosity of 38.52%, bulk density of 1.29 g/cm3, compressive strength of 42.46 MPa, and heat conductivity of 1.24 W/m·K. X‐ray diffraction analysis indicated that mullite, anorthite, α‐quartz, and diopside ferrian were the dominant phases in the specimens. Scanning electron microscopy micrographs illustrated that plenty of open pores with strip shape and closed pores with axiolitic shape existed in the specimens. Furthermore, the existence of mullite could prevent crack propagation to enhance the energy of inter‐granular fracture. It endowed the porous anorthite ceramics with high porosity, good compressive strength, and low heat conductivity. [ABSTRACT FROM AUTHOR]