This study investigates the influence of gypsum (CaSO₄·2H₂O) and calcium hydroxide (Ca(OH)₂) on the hydration behavior and mechanical properties of multi-component solid waste-based cementitious materials. The evolution of hydration products was examined by evaluating compressive strength variations at different dosages and employing advanced analytical techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric–differential thermogravimetric analysis (TG-DTG), and scanning electron microscopy (SEM). The findings reveal that gypsum addition facilitates the formation of ettringite (AFt), while Ca(OH)₂ enhances system alkalinity, promoting the precipitation and solidification of calcium silicate hydrate (C-S-H) gel. A balanced incorporation of gypsum and Ca(OH)₂ significantly improves the early compressive strength and stabilizes hydration products. This study provides theoretical guidance for the effective utilization of solid waste resources and the optimized design of cementitious materials.

Conventional concrete does not often meet engineering needs in high-impact scenarios, such as airport runways and bridges, due to its brittleness, low tensile strength and insufficient resistance to dynamic loading. Although existing rubberized concrete exhibits an enhanced toughness, granular rubber exhibits significantly poorer mechanical properties, limiting its wide application. For this reason, in this study, we propose incorporating rubber in the form of fiber and systematically investigate the effects of the rubber fiber type (NBR, silicone rubber, EPDM), admixture amount (5%, 10%, 15%) and length (6, 12, 18 mm) on the mechanical properties and impact resistance of concrete. Through cubic compression, split tensile and drop hammer impact tests, combined with SEM microanalysis and Weibull distribution modeling, the trends in properties and the mechanisms of action were revealed. The key findings included the following: (1) The equal-volume replacement of fine aggregates with fibrous rubber significantly reduced the static strength, with NBR exhibiting the lowest compressive strength loss (13.12%) compared to silicone rubber (30.86%) and EPDM (21.52%). The splitting tensile strength decreased by 10.11%, 23.67% and 13.56%, respectively. (2) The rubber dosage was negatively correlated with static strength, while an increased fiber length partially mitigated strength degradations. (3) Fibrous rubber markedly enhanced impact resistance: the final crack impact cycles of NBR, silicone rubber and EPDM were increased by 255%, 147.5% and 212.5%, respectively, compared to plain concrete. The optimal mix (15% dosage, 12mm NBR) improved the impact life by 330%. (4) Weibull distribution analysis confirmed that the impact resistance data conformed to a two-parameter model (R² ≥ 0.808), with a high consistency between the predicted and experimental results. The results of this research can be applied to transportation infrastructures (e.g., heavy-duty pavements, bridges) that require a high impact resistance, with environmental benefits. However, the study did not analyze the long-term durability (e.g., effects of freeze–thaw and chemical corrosion) or perform an economic analysis of rubber fiber processing costs; this needs to be further explored in the future to promote practical engineering applications.

Hydraulic concrete is subject to severe durability challenges when abraded by the high-speed flow of sandy water. Conventional concrete frequently needs to be repaired because of its high brittleness and insufficient abrasion resistance, while granular rubber can easily be dislodged from the matrix during abrasion, forming a new source of abrasion and increasing the damage to the matrix. For this reason, we used fibrous rubber concrete to systematically study the mechanisms of the influence of the dosage of nitrile rubber (5%, 10%, and 15%) and fiber length (6, 12, and 18 mm) on resistance to impact and abrasion performance. Through mechanical tests, underwater steel ball abrasion tests, three-dimensional morphology measurements, and fractal dimension analysis, the law behind the damage evolution of fibrous rubber concrete was revealed. The results show that concrete with 15% NBR and 12 mm fibers yielded the best performance, and its 144-hour abrasion resistance reached 25.0 h/(kg/m²), which is 163.7% higher than that for the baseline group. Fractal dimension analysis (D = 2.204 for the optimum group vs. 2.356 for the benchmark group) showed that the fiber network effectively suppressed surface damage extension. The long-term mass loss rate was only 2.36% (5.82% for the benchmark group), and the elastic energy dissipation mechanism remained stable under dynamic loading. The results of a microanalysis showed that the high surface roughness of NBR enhances interfacial bonding, which synergizes with crack bridging and stress dispersion and, thus, forms a multiscale anti-impact abrasion barrier. This study provides a new material solution for the design of durable concrete for use in high-impact and high-abrasion environments, which combines mechanical property preservation and resource recycling value. However, we did not systematically examine the evolution of the performance of fiber rubber concrete concrete under long-term environmental coupling conditions, such as freeze–thaw cycles, ultraviolet aging, or chemical attacks, and there are limitations to our assessment of full life-cycle durability.