Biomineralized self-healing concrete is a type of concrete that, during its service life, induces the generation of calcium carbonate through the participation of microorganisms or active enzymes, thereby achieving self-repair of cracks at different times. Self-healing concrete based on biomineralization can achieve sustainable crack repair and could enhance the strength and extend the service life of buildings. This article comprehensively analyzes the latest progress in bio-self-healing concrete, including microbial-based self-healing, enzyme-induced calcium carbonate precipitation (EICP), microcapsule-loaded microbial in situ remediation, and bio-inorganic mineral synergist self-healing technology. The maximum repairable width of the crack is 2.0 mm, and concrete strength can be increased by 135%. These methods offer new insights and strategies for the repair of concrete cracks, providing fundamental knowledge for the later application of intelligent engineering of bio-self-healing concrete and the analysis of micro-interface mechanisms. At the same time, they clarify the practical possibility of microbial technology in building materials science and engineering and offer key theoretical support for the long-term development of China’s construction industry.

Traditional pervious concrete poses significant challenges in optimizing both mechanical properties and permeability. To address this issue, a novel type of self-compacting recycled pervious concrete (SCRPC) featuring vertical and penetrating channels has been developed. The vertical channels were created by pulling out the reinforcement in the pre-drilled holes that were artificially created in the mold, after the concrete had been poured. However, whether this concrete has superior durability and can be employed in different sulfate drying–wetting situations remains to be investigated. This study explored the sulfate resistance and permeability of SCRPC under five drying–wetting exposure regimes: full soaking in Na₂SO₄ solution with drying–wetting ratios of 3:18, 9:12, and 18:3; semi-soaking in Na₂SO₄ solution; and full soaking in MgSO₄ solution. The results showed that the SCRPC soaked in MgSO₄ solution suffered the largest compressive strength loss (13.4%) after 150 drying–wetting cycles. Furthermore, as the drying–wetting ratio increased, the sulfate degradation of the SCRPC increased. Despite the comparable relative dynamic modulus of elasticity of SCRPC after full soaking (95.54%) and semi-soaking (92.89%), ettringite and gypsum were identified as the predominant sulfate deterioration products of SCRPC, respectively. In contrast to the two stages for traditional pervious concrete, the effective porosity of SCRPC was divided into three stages during sulfate attack: an initial rapid decline stage, a subsequent increase stage, and a final slow decline stage. The permeability coefficient of SCRPC varied from 6.00 to 6.82 mm/s under different sulfate drying–wetting exposures. In summary, SCRPC has superior sulfate resistance and permeability, and it could be more applicable in environments containing Na₂SO₄ compared to MgSO₄. This study provides basic data for the enhancement and application of pervious concrete with artificial vertical and penetrating channels.

Cement-based self-leveling mortar (CSL) is a special building material that utilizes cement as the main cementitious component, combined with a variety of admixtures. Its self-leveling characteristics enable it to effectively level and fill uneven surfaces. Additionally, the innovative green CSL developed from industrial by-products can further enhance both environmental and economic benefits. This paper systematically reviews the use of admixtures and industrial by-products in the production of CSL. The main findings include the following: (i) compared to the international ISO standard, China’s standard JC/T 985 provides more detailed testing parameters regarding fluidity, mechanical properties, and shrinkage; (ii) the effect of additives on CSL is affected by its molecular weight and structure, and high molecular weight improving the workability of the additives; (iii) industrial by-products have been effectively incorporated into CSL, leading to a reduction in reduced greenhouse gas emissions and a decreased environmental impact; (iv) macro and microanalysis results of different green CSLs show that industrial by-product gypsum has the greatest potential for application in CSL. Based on these findings, this paper offers valuable reference data for the use of admixtures and industrial by-products in CSL. Furthermore, it contributes innovatively to the sustainable development of infrastructure construction.

This study investigates the effect of γ-aminopropyltriethoxysilane (KH550)-functionalized nano-active Al₂O₃ (KH-Al) on the properties of gypsum-based self-leveling mortar (GSL) prepared from industrial by-product gypsum. First, the effects of incorporating KH-Al at dosages of 0.05%, 0.1%, 0.25%, 0.5%, and 1% on the fluidity, setting time, and mechanical properties of GSL were analyzed. Subsequently, using X-ray diffraction (XRD), hydration heat analysis, thermogravimetric analysis (TG), and scanning electron microscopy (SEM), the influences of the nanomaterial on the mortar’s morphology, hydration characteristics, and crystal forms of hydration products were thoroughly examined. Finally, by comparing the modified GSL with ordinary GSL, the mechanism of KH-Al’s action on GSL was elucidated. The results demonstrate that nano-active Al₂O₃ modified with KH550 exhibits excellent dispersibility in the GSL paste. As the dosage of KH-Al increases, both the fluidity and setting time of GSL decrease. Upon incorporating KH-Al, the mechanical properties of GSL initially improve and then decline, with optimal mechanical performance observed at a 0.5% KH-Al addition. However, when the KH-Al dosage exceeds 0.5%, excess nano-active Al₂O₃ causes nanoparticle agglomeration, which impedes the hydration process. The nucleation effect of KH-Al promotes the formation of CŜH₂ and AFt, refines the crystals of hydration products, and enhances the phase transformation efficiency of the mortar. These findings indicate that KH-Al has significant potential to improve the mechanical strength and hydration kinetics of gypsum mortar and provide theoretical support for the application of nanomaterials in gypsum building materials.

The crystal growth process directly influences crystal morphology. While the growth process of hematite crystals with specific exposed facets is relatively well understood, the growth mechanism of hematite without distinct facets, particularly porous ellipsoidal hematite, remains unclear. This study systematically investigates the hydrothermal synthesis and crystal growth mechanism of nano-porous ellipsoidal hematite. Under elevated temperatures, iron oxyhydroxide (FeOOH) undergoes a sequential transformation involving dissolution–recrystallization, interfacial nucleation, and solid-state phase transition, ultimately forming hematite. Samples collected at specific time intervals (15, 30, 45, 60, 90, and 120 min) were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). The results indicate that lattice rearrangement during the monoclinic-to-hexagonal transition and thermally driven dehydration play critical roles in generating the nano-porous ellipsoidal morphology. This work offers new insights into the controllable hydrothermal synthesis of hematite and its crystallographic transformation pathways.