Concrete structures face significant challenges in sulfate-rich environments, where sulfate attack can affect their durability and structural integrity. This study explores innovative approaches to enhancing concrete performance by integrating hydrophobic and densification technologies. It emphasizes the critical role of anti-sulfate erosion inhibitors in mitigating sulfate-induced damage, reducing water absorption, and inhibiting corrosive reactions. This research addresses prevalent issues in Chinese engineering projects where high sulfate concentrations are common, necessitating robust solutions for sulfate resistance. Through rigorous testing, including wet–dry cycling tests with 5% and 10% Na₂SO₄ solutions following the GB/T 50082-2009 standard, concrete formulations achieved exceptional long-term sulfate resistance, meeting or exceeding KS200-grade requirements. These findings provide valuable insights into optimizing concrete durability in sulfate-rich environments, offering practical strategies to enhance infrastructure resilience and reduce maintenance costs.

This study investigated the effects of NaOH molarity (6-14 M) and ground granulated blast furnace slag (GBFS) content (0-45%) on the properties of lithium slag (LS)-based cold-bonded lightweight aggregates. Bulk density, water absorption, porosity, and cylinder compressive strength were evaluated, and microstructural characterization was conducted using SEM, XRD, FTIR, MIP, and TG/DTG. Results showed that increasing NaOH molarity and GBFS content reduced water absorption (from 15.87 to 5.88%) and porosity (from 34.79 to 13.39%), while enhancing bulk density (731-1074 kg/m³) and compressive strength. At 30% GBFS, the 28-day strength increased by 224.48%, from 3.35 MPa (M6-30) to 10.87 MPa (M14-30). At 12 M NaOH, raising GBFS content from 0 to 45% increased strength by 435.62%, from 2.33 MPa to 12.48 MPa. LS without GBFS achieved 2.33 MPa, indicating inherent pozzolanic activity. Microstructural analysis revealed that performance improvement was due to enhanced geopolymerization and reduced harmful pores (> 200 nm). The M8-30 mix (915.68 kg/m³, 5.98 MPa) showed potential for meeting high-strength lightweight aggregate criteria with mix optimization. These findings demonstrate the feasibility of valorizing LS into high-performance lightweight aggregates, contributing to waste utilization and low-carbon construction.

As a new grouting reinforcement material, high‐water materials (HWMs) are being increasingly applied in different fields. This means that the environment in which these HWMs are employed are varied and increasingly complex. The dehydrating and saturation cycle of HWM caused by changes in the environment is referred to as the dry‐wet cycle. To explore the influence of the dry‐wet cycle on the mechanical properties of HWMs, uniaxial compression tests were performed on specimens with different water‐to‐cement ratios under different dry‐wet cycles. The degradation rate of the peak stress and elastic modulus increased with an increase in the water‐to‐cement ratio. The failure mode of specimens changed from splitting failure to shear‐splitting failure during the dry‐wet cycle. The results of scanning electron microscope and X‐ray diffraction showed that an HWM with a low water‐to‐cement ratio is relatively dense; therefore, the carbonization process is slow during dehydration. Raw materials were present after hydration and hardening reaction. Thus, the strength recovery ability is strong in materials with a low water‐to‐cement ratio during the saturation process. Finally, the experimental results can provide guidance for selecting materials with different water‐to‐cement ratios and control measures for dry‐wet cycle can be determined according to different engineering environments.

Lithium slag (LS), a by-product of lithium extraction processes, poses a significant disposal challenge during the rapid development of new energy technologies. In this study, LS was used to replace partially washed sand in the process of mortar production to compensate for the content of stone powder in sand. Five mortar mixes containing varying proportions of LS were prepared, and the macroscopic performance was evaluated. A comprehensive microscopic analysis, including microstructure observations, hydration product identification, and pore structure analysis, was conducted. The impact of LS on the chloride ion permeability of mortar was also investigated in this study. The results indicate that an increase in LS content gradually reduces the workability of the mortar, with a 39.29% decrease in fluidity when 40% of the sand is replaced with LS. Moreover, the compressive and flexural strengths of the mortar initially increase and then decrease with higher LS content. Microscopic tests reveal that 20% LS substitution significantly optimizes the pore structure of the mortar, resulting in a lower chloride ion permeability coefficient. Consequently, 20% LS substitution is recommended as the optimal dosage for use as fine aggregate in mortar.

The cold bonding technology for producing lightweight aggregates has received significant international attention in the fields of waste treatment and the production of green building materials. In this study, sustainable lightweight aggregate concrete (LAC) is prepared by partially replacing natural coarse aggregate with cold-bonded sewage sludge ash lightweight aggregate. The properties and microscopic characteristics of concrete were studied. The results show that the density and compressive strength of LAC decreased to 1645 kg/m³ and 12.83 MPa when the replacement rate of lightweight aggregates from 0 to 100%, indicating that the LAC can be used for non-structural LAC. Structural LAC can also be designed when 75% lightweight aggregates and 25% natural coarse aggregate are used simultaneously. In addition, the results of Scanning Electron Microscope and Nuclear Magnetic Resonance show that high lightweight aggregate content is accompanied by higher porosity and pore size inside the LAC, which reduces the resistance of concrete to drying shrinkage and freeze-thaw cycles. This research provides theoretical support for the application of SSA in sustainable LAC and reducing the damage of SSA to the environment.