Performance evaluation of pre-stressed high-strength concrete pipe piles produced with steel slag powder and ground quartz sand as composite supplementary cementitious materials

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. • PHC pipe pile concrete was prepared by using GQS and SSP as composite SCMs. • Composite SCMs can refine pores and reduce the porosity of concrete. • Composite SCMs can enhance the resistance to chloride ion permeability of concrete. • Concrete’s compressive strength prepared with 20 % GQS and 10 % SSP reached 97.5 MPa after autoclave curing.