# Effects of Performance Variations in Key Components of CRTS I Slab Ballastless Track on Structural Response Following Slab-Replacement Operations

## TL;DR

This study examines how replacing deteriorated track slabs in CRTS I ballastless tracks affects structural performance, finding that new slabs improve strength but may create new stress points.

## Contribution

The study introduces a refined finite-element model to evaluate structural response after slab replacement, revealing performance disparities and their impact on stress distribution.

## Key findings

- Deteriorated slabs showed 10.74% lower strength than retained slabs before replacement.
- New slabs exhibited a 25.26% strength increase over retained slabs after replacement.
- Old filling resin had 35.13% lower elastic modulus than required, while new resin exceeded requirements by 31%.

## Abstract

Slab-replacement operations are crucial for restoring deteriorated CRTS I slab ballastless tracks to operational standards. This study investigates the structural implications of the operation by evaluating the strength characteristics and material properties of track components both prior to and following replacement. Apparent strength was measured using rebound hammer tests on three categories of slabs: retained, deteriorated, and newly installed track slabs. In addition, samples of old and new filling resins were collected and tested to determine their elastic moduli. These empirical data were subsequently used to develop a refined finite-element model that captures both pre- and post-replacement conditions. Under varying temperature loads, disparities in component performance were found to significantly affect stress distribution. Specifically, before replacement, deteriorated track slabs exhibited 10.74% lower strength compared to adjacent retained slabs, whereas, after replacement, new slabs showed a 25.26% increase in strength over retained ones. The elastic modulus of old filling resin was measured at 5.19 kN/mm, 35.13% below the minimum design requirement, while the new resin reached 10.48 kN/mm, exceeding the minimum by 31.00%. Although the slab-replacement operation enhances safety by addressing structural deficiencies, it may also create new weak points in adjacent areas, where insufficient stiffness results in stress concentrations and potential damage. This study offers critical insights for optimizing maintenance strategies and improving the long-term performance of ballastless track systems.