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.

As a kind of solid waste, using Prestressed High-Strength Concrete Pile Waste Concrete (PPWC) as the replacement for limestone filler in asphalt concrete can not only reduce the accumulation of PPWC and increase its utilization but also avoid the increased road construction costs and environmental degradation associated with limestone mining. This study aims to investigate the effect of using PPWC filler to replace limestone filler on the road performance of asphalt concrete. Firstly, PPWC was ground into filler particles with a diameter less than 0.075 mm. The particle characteristics such as surface morphology, particle size distribution and chemical composition of PPWC filler and limestone filler were compared. Then, PPWC filler was used to replace limestone filler with different volume fractions to prepare asphalt concrete, and the water damage resistance, high-temperature rutting resistance, low-temperature crack resistance, fatigue resistance and adhesion performance of asphalt concrete were tested. The results showed that PPWC filler has a smaller particle size and rougher surface than limestone filler, and it contains Ca(OH)₂ produced by hydration. The addition of PPWC filler can effectively improve the mechanical properties of asphalt concrete without reducing its water damage resistance. PPWC filler can improve the high-temperature rutting resistance and low-temperature crack resistance of asphalt concrete, but reduce its low-temperature fatigue resistance. The low content of PPWC filler will enhance the adhesion between asphalt mortar and aggregate. However, when the content of PPWC filler exceeds 50%, Ca (OH)₂ in PPWC will reduce the adhesion between acid asphalt mortar and alkaline basalt aggregate. Therefore, the use of PPWC as filler in asphalt mixtures provides a reliable solution for the sustainable development of road materials.

Using solid waste to replace limestone filler in asphalt concrete can not only reduce the cost of road construction, but also improve the utilization rate of solid waste. In this study, PHC pile waste concrete (PPWC) was innovatively used to replace limestone filler in asphalt mixture and its effect on the physical and rheological properties of asphalt mastics was studied. Firstly, PPWC was ground into filler particles with a diameter less than 0.075 mm. The physical properties, particle characteristics and chemical composition of PPWC filler and limestone filler were compared. Asphalt mastics were prepared with different filler-asphalt volume ratios (20%, 30% and 40%) and the physical properties, high-temperature rheological properties and low-temperature cracking resistance of asphalt mastics were tested. The experimental results showed that the surface of PPWC filler is rougher and has lower density and smaller particle size than limestone filler. When the filler content is the same, PPWC filler asphalt mastics have lower penetration and ductility, higher softening point than limestone filler asphalt mastics, and the viscosity of PPWC filler asphalt mastics is more sensitive than limestone filler asphalt mastics. PPWC filler asphalt mastics demonstrated superior high-temperature stability, but poorer low-temperature cracking resistance compared to limestone filler asphalt mastics. In conclusion, PPWC fillers can be used to replace limestone fillers in asphalt mixtures. The finding of this study will provide a new solution for the construction of eco-friendly roads.