Alkali-activated concrete (AAC) is a focal point in green building material research due to its low carbon footprint and superior performance. This study seeks to enhance the impact resistance of recycled aggregate concrete (RAC) by elucidating the synergistic mechanisms of alkali activation, nano-modification, and fiber reinforcement. To this end, four mix designs, incorporating NaOH and NaOH-Na2SiO3 systems with 2 % nano-SiO2(NS), were developed and assessed through setting time, compressive strength, drop hammer impact tests, and XRD/ SEM analyses. The NaOH-Na2SiO3 system exhibited a 23.5 % increase in compressive strength over NaOH, achieving 28.41 MPa, while NS refined pore structures, elevating strength to 32.2 MPa; XRD/SEM analyses confirmed mechanisms of pore refinement and interfacial enhancement. In the optimized system, the NT12-C5 formulation, incorporating polypropylene fiber (PPF) and recycled carbon fiber (RCF), exhibited superior impact resistance, with NS enhancing interfacial bonding between carbon fiber and the matrix, resulting in a 47.8 % increase in initial crack impact energy. The Weibull model validated the reliability of impact performance. Furthermore, life cycle assessment revealed that Soil Solidification Rock Recycled aggregate concrete (SSRRAC) substantially reduced carbon emissions compared to ordinary Portland cement (OPC), while maintaining competitive economic costs. This study's innovations include: (1) synergistic optimization of low-carbon AAC performance using NaOH-Na2SiO3 and NS; (2) optimized PPF/RCF formulations promoting the reuse of waste carbon fiber; and (3) application of the Weibull model to overcome conventional statistical constraints. Collectively, these findings establish a theoretical and practical foundation for the global development of sustainable building materials.

The prestressed glass fiber-reinforced polymer (GFRP) rock bolt, characterized by its lightweight, high-strength, fatigue-resistant, and corrosion-resistant, effectively addresses the durability challenges associated with rock bolts in soil applications. This study was based on the shear test of GFRP anchor rods under varying levels of prestressing. The present study designed and conducted shear tests on GFRP anchor bolt joint surfaces under varying prestress levels, utilizing the double shear test method. Based on the experimental results, this research analyzed the influence of prestress on failure modes, shear bearing capacity, and shear deformation of GFRP anchor bolt joint surfaces. Furthermore, by employing an equivalent strain assumption in conjunction with damage mechanics theory, a predictive model for shear displacement-shear stiffness and shear displacementshear stress was established for GFRP anchor bolts. The results indicated that the failure mode of the prestressed GFRP anchor rod joint surface shear specimen was the shear failure following the splitting of the GFRP anchor rod. The shear carrying capacity of the joint surface with 20 % and 40 % pre-stressed GFRP anchor rods increased by 8.2 % and 20.3 % compared to the non-prestressed anchor rod, respectively. However, the ultimate displacements decreased by 22.7 % and 49.7 %, respectively. The initial stiffness of the 20 % and 40 % prestressed GFRP anchor rods was higher than that of non-prestressed GFRP anchor rods. However, under shear loading, the fracture strain of prestressed GFRP anchor rods decreased by 33 % and 44 %, respectively, compared to non-prestressed counterparts. The shear displacement-shear stiffness and shear displacement-shear stress relationships of prestressed GFRP anchor rods under the action of shear load were found to conform to the exponential distribution and Weibull distribution, respectively. The mechanical models proposed in this paper for shear displacement-shear stiffness and shear displacement-shear stress could effectively predict the mechanical behavior of shear damage on the joint surface of prestressed GFRP anchor rods.

The full-depth reclamation with Portland cement (FDR-PC) technology embodies an environmentally friendly approach to solving the damage to old asphalt pavement. Fatigue failure emerges as the predominant mode of degradation for FDR-PC pavement. The fatigue characteristics of the full-depth reclamation with Portland cement cold recycled mixtures were evaluated through four-point bending tests. Three contents (4%, 5%, 6%) of cement and three base-to-surface ratios (10:0, 8:2, 6:4) were utilized. The fatigue equations were derived for the mixtures using a two-parameter Weibull distribution. The results indicate that all correlation coefficients of the Weibull distribution model surpass 0.88, effectively projecting the lifespan of FDR-PC. With increases in cement contents and base-to-surface ratios, the fatigue life of the mixture extends, though with an augmentation of stress sensitivity. Comparative analysis with the fatigue equation model parameters of the current Chinese specifications for the design of highway asphalt pavement reveals that mixtures with a 4% cement content and combinations of a 5% cement content with a low base-to-surface ratio meet the requirements for inorganic-binder-stabilized soil. Additionally, mixtures with a 5% cement content and a high base-to-surface ratio, along with those with a 6% cement content, fulfill the specifications for inorganic-binder-stabilized granular materials.

To address the strength damage of red clay under dry-wet cycles, systematic conventional triaxial tests under specific circumferential pressure and scanning electron microscope observation were carried out to describe the damage evolution of soil units under load conditions of dry-wet cycle red clay microunits based on the Weibull distribution. Damage variable expressions obeying the Weibull distribution were established and the micro-parameter pore area ratio and the macro-parameter dry-wet cycle number were introduced. The cross-scale characterization of macroscopic and microscopic parameters was realized by combining the damage mechanics equation of red clay under loading. The microscopic damage intrinsic model of red clay considering the number of dry-wet cycles was constructed. The model was verified to be reasonable and effective based on triaxial tests, in which the calculation errors of the secant modulus damage threshold, probability density function shape parameter, and dry-wet cycle red clay damage stress were within 10 %, 5 %, and 5 %, respectively.