Optimization and performance regulation of pipe piles based on nano-calcium silicate hydrated (n-C-S-H)

Prestressed high-strength concrete (PHC) pipe piles are widely used in various construction projects. However, higher steam curing temperatures and times in the preparation of pipe piles severely affect material performance, while increasing cost and environmental pollution. This study investigates the use of nanoscale calcium-silicate-hydrate (n-C-S-H) to reduce curing temperature and time, ensuring high demoulding strength and short demoulding time of pipe piles. Samples with n-C-S-H content of 0 %, 1 %, 2 % and 4 % were examined under curing times of 6 and 8 h and temperatures of 60 °C and 80 °C. The results show that it is feasible to solve the problem of reduced strength of samples due to reduced temperature by adding n-C-S-H, and increasing the n-C-S-H content while decreasing the steam curing times is favourable to the compressive strength of the samples. Through lowering the curing temperature, time and n-C-S-H addition both optimize the pore structure of the samples and the delayed ettringite formation (DEF) can be prevented, also contributes greatly to the improvement of sample durability. The results provide valuable insights into the preparation of cementitious materials for pipe piles and contribute to the development of more durable and sustainable infrastructure materials.