High Performance Steam-Cured Concrete for Railway Precast Elements

This paper developed a new high performance steam-cured concrete (HPSC) incorporating grade I fly ash (FA I ) and a chemical activator, which can be used for high speed railway precast elements. Experiments were carried out to investigate the mechanical properties and durability of HPSC. The corresponding mechanism was also discussed by testing microstructure of concrete. Results indicate that the demoulding compressive strength of HPSC is more than 50MPa, and compressive and flexure strength of HPSC at later age increase well. The partial replacement of cement by FA I can significantly improve the adaptability of concrete to steam curing. Compared with that of ordinary steam-cured concrete (OSC), HPSC has lower brittleness, higher plastic deformation and less dry shrinkage, and the capability of HPSC to resist chloride attack is enhanced remarkably. Addition of FA I can improve compositions of hydration products and microstructure, and thus the durability of concrete under steam curing condition.