Mechanical properties and its prediction of sulphoaluminate cement-engineered cementitious composites (SAC-ECC) as rapid repair materials applied in winter construction

Engineered cementitious composites (ECC) are recognized as effective repair materials. However, Ordinary Portland Cement (OPC)-ECC struggles to meet the demands of emergency repair and construction in cold regions, where rapid strength development is crucial. This paper focuses on the mechanical properties and its prediction model of sulphoaluminate cement (SAC)-ECC under low-temperature curing conditions. The effects of pre-curing times (0.75 h, 1.5 h, 3 h) and curing temperatures (20 °C, 0 °C, -5 °C, -10 °C) on the mechanical properties of ECC were investigated during the early and later stages of low-temperature curing. The results reveal that the compressive and tensile strengths of SAC-ECC decrease significantly with lower curing temperatures and shorter pre-curing times. However, the tensile strain capacity increases under these conditions. Notably, after pre-curing at 20 °C for 3 hours followed by curing at -10°C, the compressive strength reached 30 MPa at 4 hours, and the tensile strain capacity exceeded 10% after 1 day. A physical model based on micromechanical parameters obtained from fracture toughness tests and single-fiber pullout tests was developed, which could simulate and forecast the evolution of tensile properties in SAC-ECC under various curing regimes and ages. The predicted outcomes align well with the experimental results, offering valuable insights for guiding engineering applications in low-temperature environments.