Rail Pads (also known as elastic under-rail layers) are engineered components installed between the rail and sleeper in railway tracks. Manufactured from rubber or polymer compounds, these pads primarily:
- Provide critical elasticity to absorb train-induced impacts and vibrations;
- Reduce operational noise emissions;
- Prolong service life of both track infrastructure and rolling stock components.
The ballast mat laying process is as follows:
Preparation of the substructure
The substructure has to be free of dust, grease, frost-free and dry as well as free of depressions and sharp-edged elevat ions. Loose objects, e. g. grit, have to be removed.
Placing of SBM
The geotextile protection layer of the mats represents the surface. According to the installation plan, the Sub ballast mat are unrolled transversely to the track axis in order to avoid joints under or parallel to the rail. When exposed to extreme temperatures and differences in temperature, the UBM should at ffrst be unrolled, placed in position and left to settle for a few hours before gluing. This allows the material to recover from compression.
Changes in length of the mats due to temperature are a physical process and are completely reversible. If necessary, these can be compensated by either pulling or cutting.In the case of very tight curves (and thus large angular deviations), the mats can be adjusted on site by cutting the long side in a wedge shape.
Adhesion to the substructure
To avoid displacement during ballasting, the mats have to be glued to the subtructure . Ideally a two-component solvent-free polyurethane adhesive (approx. 0.4 kg/m2 USM) is used. A suitable
adhesive can be supplied directly by GNEE RAIL.
The surface temperature should be at least +5 °C at the time of gluing.The adhesive is applied in dots in order to enable proper drainage underneath the UBM. Firstly one half of the UBM is folded from one sidewall to the other one in order to apply the glue. Immediately afterwards, the mat is folded back again. After this half is glued, the same steps are repeated for the other half.
Connection of ballast mat / sealing of joints
The mats are connected with approx. 9 cm wide geotextile strips, which are supplied by GNEE RAIL. These strips are either ffxed with a hot air welding machine or glued with UBM adhesive. Therefore, the butt joints are covered completely.
To illustrate this, the geotextile strips on the left are coloured in orange.
It must be ensured that after completing this section of the installation the sealed mat joints are visually checked again.
Installation of side mats
The side mats are fully glued to vertical parts of the structure. A two-component polyurethane adhesive or a two-component bitumen compound (solvent-free, cementbound) is recommended. The adhesive requirement is approx. 0.8 kg/m2 side mat. Butt joints of side mats are not sealed with geotextile strips.
Supply of ballast
Ballasting should be carried out as soon as possible after welding the butt joints and attaching the side mats .Provided they are glued to the substructure and the adhesive has cured, GNEE RAIL Ballast Mat may be driven over at walking speed by rubber-tyred vehicles. Construction machines with crawlers are not permitted.Sudden breaking,acceleration and strong steering must be avoided.
Continuation of works
After the ballast mat is consistently covered with at least20 cm of ballast, all further superstructure work can be carried out - even using heavy machinery.
GNEE RAIL is a professional trading company focusing on the export of railway fasteners, committed to providing reliable rail connection products for global railway construction projects. The main products include a full range of railway fasteners such as various spring clip fastener systems, sleeper bolts, anti-loosening washers and insulating components, which are suitable for various application scenarios such as conventional railways, heavy-duty railways and urban rail transit.
With rich international trade experience, we have established an efficient supply chain system and logistics network to ensure timely delivery of products. We insist on being customer-oriented, winning market recognition with high-quality products and services, and look forward to establishing long-term and stable cooperative relationships with global customers.