Thermal expansion deformation of cementitious grout material during heating process

Cementitious grout for sleeve of rebar splicing is the critical load-transfer medium for prefabricated concrete structures, and its high-temperature thermal deformation is critical to structural fire safety. Numerous studies have investigated the ambient performance and residual strength of thermally damaged grout. Nevertheless, systematic explorations into its thermal deformation across heating and temperature holding stages are still inadequate. To investigate the thermal deformation behaviour of sleeve grout during the heating and temperature holding processes, the grout was heated from ambient temperature to 100, 200, 300, 400, 500, 600, 700 and 800 °C. The linear deformation rate and linear deformation coefficient were measured throughout the heating and temperature-holding processes. Between 100 and 500 °C, deformation rose first then fell. From 600 to 800 °C, deformation kept growing steadily. The linear deformation rate was measured to be 0.397% at 800 °C. The linear deformation rate reached 1.019%, which was 2.6 times the value before the temperature holding process. These results provide thermal expansion parameters for numerical fire analysis and post-fire assessment of grouted sleeve connections. These quantified deformation thresholds and thermal parameters offer fundamental data for fire simulation and post-fire evaluation of grouted sleeve joints, filling the research gap on the dynamic high-temperature deformation of sleeve grout.