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.

Steel slag-based geopolymer foamed concrete (SSGFC) provide a promising value-added and carbon-neutral strategy for the re-utilization of SS, and the strength and physical properties of SSGFC are essential to its practical application. Therefore, this study proposes to use emulsified asphalt (EA) to improve the pore structure, compressive strength, water resistance and thermal insulation properties SSGFC. Firstly, different contents of EA were added into the foaming solution to prepare modified foam, and then SSGFC samples were prepared by using modified foam and steel slag-based geopolymer. The fresh properties, microstructure, pore structure, reaction products and physical properties of SSGFC samples were investigated. The results indicate that EA can reduce the fluidity and settlement value of the paste and increase the setting time. The addition of EA leads to a decrease in hydration products, but it can reduce the average pore diameter of the SSGFC and improve its pore diameter distribution. The SSGFC sample prepared by modified foam with 10 % EA showed the best physical properties. Compared with the control group, its compressive strength increased by 21.4 %, water absorption decreased by 16.5 %, and thermal conductivity decreased by 31.3 %. Therefore, EA shows significant potential to enhance the performance of SSGFC, thus providing reliable support for its practical applications.

Aimed to address the low utilization rate of steel slag (SS) and its challenge in resource utilization in China, this study developed ternary geopolymers made by high-content (50%) SS together with fly ash (FA) and granulated blast furnace slag (GBFS). The effects of GBFS content (0–40%) and curing methods (water curing, standard curing, sealed curing, and heat curing) on the working performance and microstructure of geopolymers were investigated. Microscopic analysis such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG-DTG), and scanning electron microscopy (SEM) were utilized to investigate the hydration process and products of geopolymers under different curing conditions and GBFS content. The results indicated that when the GBFS content increased from 0% to 40%, the fluidity of the mixture decreased by 11.7%, the initial setting time of the geopolymer slurry decreased by 76%, and the geopolymer mortar's 28d compressive strength increased from 31.9 MPa to 60.6 MPa. At room temperature, the geopolymer mortar's 28d compressive strength was higher under standard curing (70.8 MPa) compared to water curing (57.5 MPa) and sealed curing (68 MPa). The geopolymer mortar cured at 60 °C for 24 h exhibited the highest 28d compressive strength (76.3 MPa). However, excessively high curing temperatures or prolonged durations led to more shrinkage cracks and reduced the compressive strength. The microscopic analysis revealed that the main gel products of ternary geopolymer were C-(A)-S-H gel. The amount of gel products is directly related to the strength of geopolymers. The developed ternary geopolymer has the potential to promote the large-scale utilization of SS in the concrete industry, making a significant contribution to sustainable development.