One-part alkali-activated materials (AAM), a low-carbon alternative to cement, can reduce CO₂ emissions while improving the utilization of industrial by-products. In this study, basic oxygen furnace slag (BOFS) was activated by alkali fusion with different contents of sodium hydroxide (NaOH), and the optimum NaOH content was selected by the mineral phase composition and micromorphology of alkali-fused basic oxygen furnace slag (ABOFS). Then, ABOFS and ground granular blast furnace slag (GGBFS) were used to prepare one-part AAM pastes, and the effects of GGBFS content on the reaction products, microstructure, leaching characteristics and mechanical strength of one-part AAM pastes were studied. Finally, the life cycle assessment (LCA) of one-part AAM pastes was conducted. The results showed that alkali fusion activation promoted the formation of reactive mineral phases in BOFS and increased its specific surface area. The optimum NaOH content for alkali fusion activation is 10 wt%. The reaction products of one-part AAM pastes primarily consisted of C-(N-)A-S-H gel and hydrotalcite. As GGBFS content increased from 0 wt% to 80 wt%, the amount of gel products first increased and then decreased, peaking at 60 wt%. The addition of GGBFS reduced the porosity of pastes and increased the proportion of gel pores, resulting in a denser structure. Therefore, the compressive strength of one-part AAM pastes increased with the increase of GGBFS. LCA results indicate that the global warming potential (GWP) of one-part AAM is significantly lower than that of ordinary Portland cement. The findings of this study provide new insights into the application of BOFS in AAM.

Utilizing industrial solid waste as supplementary cementitious materials (SCMs) in the production of pre-stressed high-strength concrete (PHC) pipe piles can reduce the consumption of cement, thereby promoting the sustainable development of the pipe pile industry. This study focused on optimizing the use of composite SCMs including ground quartz sand (GQS) and steel slag powder (SSP) to enhance the mechanical properties and durability of PHC pipe pile concrete. The effects of GQS and SSP on the reaction products, microstructure, pore structure, mechanical properties and durability of PHC pipe pile concrete were investigated. Experimental results showed that due to the filling effect and pozzolanic effect of GQS and SSP, composite SCMs not only improves the microstructure of the interfacial transition zone between paste and aggregates in PHC pipe pile concrete, but also reduces the porosity of concrete and improves its pore structure, thereby enhancing the compressive strength and durability of concrete. When the GQS content is 20 % and the SSP content is 10 %, compared to the control group with 100 % cement, the concrete's porosity decreased by 19.3 %, the chloride ion diffusion coefficient decreased by 47.1 %, and the compressive strength increased by 3.4 %. The findings of this study provide a scientific basis for the resource utilization of steel slag and offer theoretical support for the low-carbon and sustainable development of PHC pipe pile industry.

This study characterized the morphology, high-temperature property, rheological property, adhesion, cohesion, and chemical component of asphalt binder under aqueous solutions of different pH values. Then the physicochemical properties of asphalt binder were comprehensively evaluated by the improved radar chart. The properties of asphalt binder stripped layer-by-layer were explored to elucidate its gradient damage behaviors. The results indicate that the pH 3 solution reveals the greatest impact on the morphology of 90 asphalt (90 A) and styrene-butadiene-styrene modified asphalt (SBS MA), leading to the wide cracks on 90 A and the network cracks on SBS MA. The comprehensive assessment index of 90 A exposed to pH 3, pH 5, pH 7, pH 9, and pH 11 solutions can be reduced by 20.8%, 20.2%, 1.5%, 14.0%, and 25.5%, respectively. While for SBS MA, its corresponding values variation are 23.2%, 17.7%, 4.6%, 8.7%, and 13.0%, respectively. The acid solutions significantly affect the comprehensive properties of 90 A, but their pH value has little effect. 90 A exposure to the higher pH value of alkali solution reveals the worse comprehensive properties. Acid solute and alkali solute can aggravate the effect of aqueous solution on the comprehensive properties of SBS MA, and the degree of aggravation increases with the increase of solute concentration. The properties of asphalt binders exhibit varied gradient damage behaviors under different solute environments. The most serious damage occurs at 25–50 µm of 90 A and 0–50 µm of SBS MA. This study facilitates an accurate understanding of the mechanism of pavement distresses and composition design and construction utilization of asphalt binders.