16.Method for detecting damage and repairing slab track cement asphalt mortar layers

  • A method has been proposed to use track inspection data to detect damaged sections in the CA mortar layer under slab track.
  • A method for repairing the gaps in the upper CA mortar layer was developed, which reduces material costs by 40% compared to existing renovation methods.
  • A method was then developed to carry out repairs on large-scale damage to the CA mortar layer. This new renovation method reduces costs by 50% compared to present methods which completely replace the CA mortar layer.

Slab track can be subject to major damage due to gaps forming underneath it or erosion on its sides up to several dozen centimetres in size, due to frost damage etc. This kind of damage is very cumbersome to repair. The change in support due to deterioration appears on each 5m track slab. Using this characteristic, a more efficient method by 5m-chord longitudinal level irregularity was proposed to detect deteriorated slab track sections from track inspection data (Fig. 1).
Gaps under track slabs can be repaired using resin injections. However, due to cost of materials and workability, this method is seldom employed. As such, a new method for renovating slab track was developed which reduces costs by 40% compared to existing materials. The method uses high-fluidity CA milk (slurry) injected using a sandy mould to fill the gap (Fig. 2).
A new method was then developed to renovate large sectional areas, whereby an inspection rod is used to estimate the extent of the deteriorated area, which is subsequently cleared using a water jet and then injection-filled using frost-damage resistant renovative CA mortar (Figs. 3 and 4). This method reduces the cost of repairing damaged sections by 50% compared to present methods which completely replace the CA mortar layer.
Results from applying the gap repair and large-section renovation work to a commercial line demonstrated that dynamic displacement of the track was reduced, and could be kept below 1/10 (Fig. 5).

Fig.1 Correlation between longitudinal level irregularity and track slab displacement
Fig.2 Gap repair method
Fig 3 Example of extensive deterioration (condition at the surface)
Fig 4 Work with the water jet
Fig 5 Reducing dynamic displacement through large section repair