The influence of graphene oxide (GO) and polyvinyl alcohol (PVA) fiber on the mechanical performance, durability, and microstructure of cement-based materials was investigated in this study. The results revealed that compared with a control sample, the mechanical strength and durability of cement-based materials were significantly improved by adding PVA fiber and GO. The compressive and flexural strength at 28 d were increased by 30.2% and 39.3%, respectively. The chloride migration coefficient at 28 d was reduced from 7.3 × 10⁻¹² m²/s to 4.3 × 10⁻¹² m²/s. Under a sulfate corrosion condition for 135 d, the compressive and flexural strength still showed a 13.9% and 12.3% gain, respectively. Furthermore, from the Mercury Intrusion Porosimetry (MIP) test, with the incorporation of GO, the cumulative porosity decreased from more than 0.13 cm³/g to about 0.03 cm³/g, and the proportion of large capillary pores reduced from around 80% to 30% and that of medium capillary pores increased from approximately 20% to 50%. Scanning electron microscope (SEM) images showed a significant amount of hydration products adhering to the surface of PVA fiber in the GO and PVA fiber modified sample. The addition of GO coupling with PVA fiber in cement-based materials could promote hydration of cement, refine the microstructure, and significantly improve mechanical strength and durability.

To address the environmental pressures and resource waste caused by massive stockpiling of steel slag, this study developed a carbonated steel slag pervious concrete binder using 40% steel slag powder as the primary cementitious component combined with CaO and MgO. The mechanical performance evolution was investigated, while XRD, SEM, and TG-DTG microcharacterization techniques were employed to reveal the carbonation mechanism and strength formation principles. The results demonstrate that when CaO and MgO contents reached 5% and 15%, respectively, the 28d compressive strength of mortar increased by 134.49% compared to the reference group. Microstructural analysis confirmed that CaO reacted to form CaCO₃ crystals, while MgO enhanced strength by regulating CaCO₃ crystal morphology to optimize product structure. Using steel slag as an aggregate, carbonated steel slag pervious concrete was prepared to investigate the influence mechanisms of B/A ratio and W/B ratio on compressive strength, permeability coefficient, and carbonation effects. The post-carbonation strength increase was adopted to evaluate carbonation efficiency. Increasing B/A ratio enhanced paste filling in aggregate voids, raising 28d compressive strength to 24.76 MPa, but thickened paste coating layers reduced permeability coefficient to 0.33 mm/s while impeding CO₂ diffusion, decreasing carbonation strength growth rate by 22.76%. Initial W/B ratio elevation improved workability to increase strength to 23.76 MPa, whereas excessive water caused paste sedimentation and strength reduction. As W/B ratio rose, permeability coefficient decreased by 65.6%, while carbonation strength growth rate increased. The carbonated steel slag pervious concrete contained approximately 82% steel slag, demonstrating high resource utilization efficiency of steel slag and significant potential for carbon emission reduction.

To address the problems of high moisture content, fine particle size, and limited conventional reutilization of stainless steel slag mud (SSSM), controlled low-strength material (CLSM) was prepared using SSSM as the primary solid component and cement together with ground granulated blast furnace slag (GGBS) as cementitious materials. The effects of GGBS replacing cement and SSSM, respectively, on the properties of CLSM and their variation patterns were investigated. Its solidification mechanism was analyzed through simulated control tests, X-ray diffraction (XRD), thermogravimetric–differential thermogravimetric analysis (TG-DTG), and scanning electron microscopy (SEM). The results show that, when GGBS replaces cement, the water-to-solid ratio and bleeding rate increase, while the compressive strength at all curing ages decreases overall; however, the 28 d strength still meets the requirement for CLSM. When GGBS replaces SSSM, the water-to-solid ratio and bleeding rate increase with GGBS fraction, and the compressive strength at all curing ages increases overall. At a GGBS fraction of 18%, the water-to-solid ratio reaches 0.363, the bleeding rate reaches 5%, and the 28 d and 60 d compressive strengths reach 7.3 and 11.2 MPa, respectively, representing increases of 23.3 and 21.4 times compared with the system without GGBS (0.3 and 0.5 MPa). The simulated SSSM substitution tests show that a synergistic solidification effect exists between SSSM and GGBS and contributes to strength development. Microstructural analysis shows that GGBS undergoes hydration under the alkali–sulfate environment provided by SSSM, generating ettringite (AFt) and calcium silicate hydrate (C-S-H gel), which fill pores and thereby enhance strength, while calcium hydroxide (Ca(OH)₂) provides an alkaline environment and promotes the participation of potentially active components in SSSM in the synergistic solidification process.

Internal curing can improve the water supply needed for shrinkage compensation in ultra-high-performance concrete (UHPC). This study investigated a magnesium oxide expansive agent (MEA) combined with presaturated perforated cenospheres (PCs) in a cement-silica fume-blended industrial by-product system. Setting time, flow spread, compressive strength, autogenous and drying shrinkage, internal relative humidity, hydration heat, thermogravimetric behavior, mercury-intrusion-accessible pore structure, and local morphology were examined. MEA alone reduced shrinkage but decreased flow spread and compressive strength as its dosage increased. At a fixed MEA dosage, the PC-containing mixtures showed lower shrinkage and higher flow spread and strength, alongside delayed setting. M6P8 showed 62.8% lower autogenous shrinkage at 168 h after final setting and approximately 76% lower drying shrinkage at the end of the 180-day drying test than Ref. It achieved a 28-day compressive strength of 157.0 MPa, close to the Ref mean of 156.0 MPa. Higher PC dosages were associated with higher late-age internal relative humidity and, relative to MEA alone, higher cumulative heat release and lower intrudable pore volume. These observations are consistent with reduced self-desiccation and continued hydration, but do not directly measure PC water release or MgO hydration. PC replacement simultaneously reduced cement content and introduced stored water; the observed response therefore represents combined effects and does not establish a synergistic interaction.