Towards a better binder for pervious concrete: A case study on the flexural strength of fibre-reinforced high-strength cementitious paste (F-HSCP) under different curing conditions

Adding fibres can help increase the performance of the binder and, thus, the mechanical performance of the pervious concrete. However, their performance under various curing conditions is questionable. This study investigates the mechanical performance and microstructure evolution of fibre-reinforced high-strength cementitious paste (F-HSCP) incorporating Ultra-High Molecular Weight Polyethylene fibre (UF), Glass fibre (GF), and Steel fibre (STF) across four curing conditions: standard 28-day water curing (W-Type), steam curing for 48 h (S-Type), 90 °c, 48-hour hot water bath curing (H-Type), and 8-hour, 1 MPa pressure, 180 °c autoclaved curing (A-Type). Key findings indicate that W-Type curing is the best way to uniformly enhance the flexural strength up to 23.9 MPa. A-Type curing reduced strength by approximately 14 % (to 20.5 MPa) due to non-uniform hydration products. UF at low dosages benefits from S- and H-Type curing, achieving 22.47 MPa at 0.7 % fibre dosage, which provides higher flexural strength than other curing methods. GF reinforcement proved to be unsuitable, with A-Type curing causing a 12.86 % reduction in initial cracking strength at 2.0 % dosage and reaching only minimal ultimate strength improvements (<5 %) across all conditions. Conversely, STF demonstrated superior performance with strengthened fibre-matrix bonds, where a 3 % dosage increased initial crack strength by 21.87 % under S-Type curing, while a 4 % dosage enhanced ultimate flexural strength by 224.31 % and achieved good toughness. These insights offer critical guidance for maximising fibre efficiency in F-HSCP across various curing conditions, which is critical for its binding effect in pervious concrete.