Large amounts of steel slag (SS) stockpiled and buried leads to land occupation, and is prone to cause soil and water contamination. Partially replacing natural minerals in pavement construction can contribute to the rapid consumption of stockpiled SS, but its poor volume stability limits its widespread adoption into engineering applications. Meanwhile, the potential leaching of hazardous substances (HS) should also be emphasized. This study prepared different pretreated SSs and asphalt mixtures. The differences and improvement mechanisms of the pretreatment on the SS properties were investigated through micro-morphology and chemical composition analyses. The physical properties of different SS and the long-term volume stability and moisture damage resistance of the steel slag asphalt mixture (SSAM) were tested. Moreover, a revised HS leaching test method for the SSAM was proposed, and the effectiveness of various pretreatment methods in reducing HS leaching was evaluated. The results revealed that the porous characteristics and free oxides contained in SS were the main obstacles to their large-scale application in pavement engineering. Natural aging, thermal immersion, and acid modification alter the composition of SS through chemical reactions and accelerate the consumption of free oxides. The polymer film formed by the silane coupling agent on the SS surface mitigated the environmental effects on the performance. The long-term performance of the SSAMs was improved, and the amount of HS precipitated was significantly reduced. Acetic acid modification and surface treatments are recommended because they are more effective in improving moisture damage resistance and reducing potential adverse environmental impacts. The findings are significant for reasonable pretreatment and application of converted SS as well as for contributing to the sustainable development of transportation infrastructure.

Amaranth (Amaranthus hypochondriacus L.) is a potential forage crop with a high yield and crude protein (CP) content; however, establishment methods need to improve for the crop to be less sensitive to typhoons. Optimal establishment, cultivation, and utilization in amaranth were examined in a variety of seasons and methods of establishment in 2021-2023. Four methods were examined: (1) direct seeding in rows, (2) direct seeding in spots, (3) soil seed balls, and (4) transplant pretreatment methods under a randomized blocked design (n = 3). Sowings every month from April to August were applied only in 2021, while establishments in April, May, and August with both pretreatment methods were applied in 2022 and 2023. The establishment in August successfully escaped damage from typhoons. The direct seeding of either rows or spots showed marginal success in establishment compared to stable establishment in pretreatment methods. In 2022 and 2023, the highest yield and CP content were achieved in soil seed balls plots in April and in both pretreated plots sown in August, respectively. The quality of silage fermentation showed a high pH, ranging from 4.52 to 6.39, due to the high CP content in 7.59-18.36% dry matter (DM). Sowing in April or August established with soil seed balls can avoid typhoon damage to have stable forage yields and can be processed with a favorable quality of amaranth silage in the region.