Criteria for repairing damages of CA mortar for prefabricated framework-type slab track

• Influence of CA mortar damages on the structure’s carrying capacity was studied.
• A 3-D FEM of framework-type slab track reflecting CA mortar damages is established.
• A dynamic test of the slab track with damage to CA mortar has been conducted on site.
• Recommendation of the classification and criteria of mortar damages was put forward.

Damage of bagged cement–emulsified asphalt (CA) mortar tends to create voids underneath the track slab and will reduce the carrying capacity of the track structure, which is contrary to its design purpose of providing a long-term, safe and reliable service. In this paper, a study on the criteria for repairing damages of the CA mortar was conducted by establishing a 3-D FEM of the prefabricated framework-type slab track on elastic foundation. In order to verify the calculation results, a field test was carried out by comparison of the slab with or without the repair of damaged CA mortar. Based on the limited results in this study, the recommended values for criteria of repairing damages to CA mortar are preliminarily put forward. The results show that the mortar damages have the most adverse impacts on the carrying capacity of the track slab and CA mortar, but less impact on the concrete base. The numerical simulation indicates the critical length of 0.20 m and critical width of 0.40 m for the transverse damage type, and the critical length of 0.60 m and critical width of 0.20 m for the longitudinal damage type. For the damage type of the interfacial loss of bond, a critical gap size of about 2 mm was also deduced. If the actual dimensions of the damage to CA mortar are greater than the critical values, the tensile stress of track slab or the compressive stress of CA mortar will increase significantly and may exceed their characteristic value; and the dynamic deformation and vibration performance of track structure becomes apparent; the fatigue damage of CA mortar under the area adjacent to the damage would also be accelerated.