This study investigates the effect of micr-oaggregate filling with copper tailing on the pore structure of cement paste containing copper tailing (CPCT). The particle size of the CPCT and the pore structure of CPCT were analyzed by laser particle size analysis and mercury instruction porosimetry (MIP). Results showed that at the early stage of curing time, with increasing copper tailing content, the compressive strength of cement mortar with copper tailing (CMCT) was lower, and the porosity and pore diameter of CPCT were higher and greater; with the extension of curing age, when the content of copper tailing was less than 30%, the compressive strength of CMCT and the porosity of CPCT changed slightly with the increase of the content of copper tailing. However, the maximum hole diameter of CPCT decreased gradually (a curing age between 7 d and 365 d under standard conditions). Scanning electron microscopy analysis showed that at the early stage of cement hydration in the CPCT, the copper tailing did not fill the pores in CPCT well, while in the later stage of cement hydration, the microaggregates of copper tailing filled the pores well and closely combined with the surrounding hydration products. In the later stage of cement hydration, the microaggregate filling of copper tailing was primarily responsible for the strength increase of the CMCT.

The surface corrosion of 3 type concrete beams in hostile environment is researched by measuring concrete beams surface corrosion content, and the effect of test condition, concrete strength and corrosion time on concrete beams surface corrosion is analyzed. The result show that corrosion time is positively related to corrosion time; the beginning peeling time is longer with the increasing of concrete compressive strength; the capacity of concrete anti-stripping is increased with the increasing of concrete compressive strength. The formula of predication concrete beams surface stripping is set up by use of test data, which can be present in predicating concrete service life.

Immersion in salt-lake solution was adopted to periodically test the concrete chloride-ion diffusion coefficient. The regression analysis was also completed. Also investigated was the time-dependent law of concrete chloride-ion diffusion coefficient with time. The influence of chloride-ion concentration in solution, water-to-cement ratio, and corrosion time on the largeness and accumulation rate of the concrete chloride-ion diffusion coefficient was also analyzed. Test results show that the concrete chloride-ion diffusion coefficient gradually decreased with increasing time and increased with increasing chloride-ion concentration in a salt lake . Taking into account the influence of factors such as water–binder ratio, chloride-ion concentration, and time-varying characteristics, a multi-factor calculation model for the concrete chloride-ion diffusion coefficient was established. Combining the prediction results and the measured data reported in this paper, the effectiveness and applicability of the established concrete chloride-ion diffusion coefficient calculation model were compared and verified, and the durability design and service life of a concrete structure under cool chlorine were compared. The results of analysis provide important boundary conditions.

To promote the high-value utilization of construction and demolition waste in cementitious materials, this study proposed an integrated strengthening strategy combining recycled coarse aggregate modification with cementitious matrix optimization. Recycled coarse aggregates with particle sizes of 4.75–31.5 mm were prepared from demolished concrete waste collected in Aksu, Xinjiang, China, and treated by particle shaping, alkaline solutions, and polyvinyl alcohol (PVA). Silica fume and a polycarboxylate superplasticizer were used to optimize the cementitious matrix. The physical properties of recycled aggregates, the mechanical performance of recycled aggregate concrete, and the mechanical and durability performance of high-content recycled aggregate cement-stabilized materials were evaluated. Particle shaping reduced water absorption and the crushing index from 6.8% and 14.4% to 5.6% and 12.6%, respectively. After treatment with 5% NaOH and 10% PVA, the apparent density increased to 2779 kg/m³, whereas water absorption and the crushing index decreased to 3.3% and 8.3%, meeting Class II recycled coarse aggregate requirements. With 10% silica fume and 0.2% superplasticizer, the 28-day compressive strength of recycled aggregate concrete prepared with the optimized aggregate and matrix reached 27.6 MPa, corresponding to 97.5% of that of natural aggregate concrete. The combined modification approach improved mechanical performance and reduced drying shrinkage, but the replacement ratio should be limited to 60% to satisfy the F50 freeze–thaw requirement under the tested conditions.

To improve the durability of concrete in the saline environment of southern Xinjiang, concrete was modified with basalt fiber (BF) and waterborne epoxy (WEP). A one-year outdoor natural-exposure test in Aksu, Xinjiang, systematically investigated the corrosion resistance and multi-scale deterioration behavior and durability of the modified concrete. Compared with C0, the BF2E2 mixture reduced the mass loss rate and flexural strength loss rate by 54.65% and 37.20%, respectively, while increasing the relative dynamic elastic modulus by 14.55%. The modified mixtures also showed decreased total porosity, reduced average pore area, and narrowed crack widths, with significantly attenuated diffraction peaks of corrosion products. Threshold-crossing times obtained by extrapolation indicated that the earliest threshold-crossing time of BF2E2 was extended by 62.14% compared with C0, with the relative dynamic elastic modulus serving as the governing durability criterion. Mechanistic analysis revealed that BF and WEP acted collaboratively through fiber bridging and polymer filling, forming a dual-reinforcement network that suppressed deterioration from the microstructural to the macroscopic scale. These findings provide guidance for the durability-oriented design of concrete structures in saline environments.