Meso-scale mechanical damage behavior of ECC-repaired wide and narrow joints of longitudinally continuous slab tracks

The narrow and wide joint concrete of longitudinally continuous slab tracks is prone to diseases such as crushing and cracking under temperature load, which affects the integrity and durability. Therefore, this paper introduces high-toughness Engineered Cementitious Composites (ECC) as the repair material for the wide and narrow joints and conducts experimental and numerical investigation on the temperature-induced meso-scale damage characteristics. Firstly, experimental tests were carried out to determine the bonding parameters between concrete and ECC. Then, a macro-meso simulation model of longitudinally continuous slab tracks that accounts for the meso-scale characteristics of the wide and narrow joints and the nonlinear interlayer bond behavior was constructed using a sub-modeling approach. Finally, the meso-scale damage behavior and interface damage characteristics of the wide and narrow joints under different fiber contents, matrix strengths, and interface bond strengths under overall temperature loads were studied. Results show: (1) The fracture load of wide and narrow joints with 2.5 % fiber added is 31 % higher than that without fiber added, but it has little effect on the initial crack load and displacement. (2) The influence of matrix strength on damage follows a linear pattern. When the concrete strength increased from C35 to C60, the maximum compressive damage factor of the wide and narrow joints under temperature rise decreased from 0.9237 to 0.4752. (3) Improving the normal strength of the bonding surface and reducing the tangential stiffness can effectively delay the initiation of interface damage.