PREVENTING EROSION PUMPING
Erosion pumping has always been a problem in ballasted track, particularly on weakly cemented mudstones or over consolidated clays.
These soils have a high shear strength and as such do not need a deep trackbed to support track loading, yet if unprotected the upper surface degrades easily to a slurry when exposed directly to water.
Tracktex® is a multilayer specialist composite with a unique microporous filter media protected by specially engineered protective nonwoven geotextiles. Tracktex® is able to effectively facilitate the passage of liquid under pressure, but the pores are such that the passages of clay fines are prohibited. Without pressure, water cannot pass though the filter, therefore any underlying clay formation will, over time, dry out and have an improved modulus.
Tracktex® is a unique patented geocomposite and the result of over a decade of research by trackbed engineers and materials scientists. Its specialist filter system improves trackbed quality over time and has been proven to significantly increase maintenance intervals. The use of Tracktex® is the most cost effective way of preventing and correcting mud pumping failure. Rainwater is unable to penetrate the micro-porous filter and is drained laterally to the side of the track while pore water below the Tracktex® is relieved upwards under cyclic loading which aids residual slurry to dry out as the pore water is dissipated.