Study on the Curing Kinetics and Thermal Response of Repair Slurry for Interface Damage in China Railway Track System II Slab Ballastless Track

To characterize curing heat release and temperature evolution during interface damage repair in China Railway Track System (CRTS) II slab ballastless track, the curing kinetics and thermal properties of repair slurry for interface damage (RSID) were investigated. Non-isothermal differential scanning calorimetry (DSC) was conducted at four heating rates, and the apparent activation energy was determined using the Kissinger, Ozawa, and Starink methods. An n-order curing kinetic model and a two-parameter (m, n) autocatalytic curing kinetic model were established and compared. The specific heat capacity and thermal conductivity were determined using laser flash analysis (LFA), and corresponding temperature-dependent constitutive models were established. These material properties were incorporated into a three-dimensional transient heat transfer finite element model considering curing heat release, which was validated through curing temperature-rise experiments. The results show that the curing exothermic peak shifts toward higher temperatures with increasing heating rate. The average apparent activation energy obtained from the three methods is 55.21 kJ/mol. The two-parameter autocatalytic model provides better agreement with the experimental curing-rate curves than the n-order model, with R2 values exceeding 0.960. The specific heat capacity increases approximately linearly with temperature, whereas the thermal conductivity exhibits an exponential growth trend. The simulated and measured temperature histories agree closely, with an R2 value of 0.979, a peak temperature difference of 0.2 °C, and a difference of 3 s in the time to reach the peak. The simulated temperature field shows greater heat accumulation in the interior, with higher temperatures internally and lower temperatures near the boundaries. These findings provide material parameters and a thermal analysis basis for optimizing interface damage grouting repair processes in ballastless track and support subsequent analyses of thermal deformation and the development of measures to control secondary damage during repair.