Maintenance Techniques
Sand Blankets

The UK rail industry moved to mechanical trackbed maintenance techniques in the mid 20th century. Prior to this the placing of new ballast beneath the sleepers was rare as vertical track geometry faults were corrected by hand packing of ballast and did not disturb the deep, well consolidated ballast layer. This lower ballast would break down considerably over time, but would retain it’s granular characteristics and so continue to function as a drainage and load spreading layer. 

Such mechanical maintenance techniques sped up the ballast maintenance process, but required deep layers of clean ballast to be successful. This often necessitated the removal of the well graded granular layers which provided good separation between ballast and subgrade, leading to rapid subgrade erosion and consequent development of wet spots. 

The Solution

The solution to this was to introduce a protective well graded aggregate beneath the ballast in a process known as sand blanketing. Over time an effective grading envelope was found for blanketing sand, and typically a 300 mm layer was used. This proved to be a highly successful method to cure subgrade erosion, and is still used today.

To achieve the required 300mm thickness requires a large volume of excavation and the associated material disposal costs. There is also a large material import requirement which needs to meet the tight grading envelope, making this process expensive, slow and environmentally costly.

During the 1980’s British Rail started considerable research efforts to investigate whether using geotextile filter layers could help reduce or remove the need for sand blankets to treat mud pumping caused by subgrade erosion.

Preventing Mud Pumping, Ensuring Track Stability

Comprehensive Support Delivers Trackbed Performance

At GEOfabrics, we provide technical support to help you get the most out of TrackTex and address the cause of mud pumping. This ensures the stability and performance of your tracks. Our team of experts utilizes advanced techniques and technologies to deliver effective solutions tailored to your specific needs

Professional Development Hours

GEOfabrics continuing education sessions provide technical training on specifying and using TrackTex. These sessions contribute to PDH hours.

Trackbed Stabilization

Geosynthetics are widely used as a way to improve ballast performance under railways. GEOFabrics RK4 is a geocomposite comprising a stabilizing geogrid bonded to our RK1 needlepunched non-woven sep...

Symptoms of Mud Pumping

The symptoms of Mud Pumping are similar to those of life expired ballast, i.e. wet spots appearing at the surface of the ballast accompanied by rapid deteriorating of track geometry. However, from ...
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