Application of a new thermal insulation layer to subgrade

• Published in: Proceedings of the Institution of Civil Engineers - Transport
• Main Authors: Wei, Haibin, Zhang, Yangpeng
• Format: Article in Journal/Newspaper
• Language: English
• Published: Thomas Telford Ltd. 2022
• Subjects: Transportation; Civil and Structural Engineering; permafrost
• Online Access: http://dx.doi.org/10.1680/jtran.18.00016; https://www.icevirtuallibrary.com/doi/pdf/10.1680/jtran.18.00016

The use of thermal insulation has great potential for preventing frost damage to roads in seasonally frozen areas, in fact more so than in permafrost. With the aim of recycling the vast quantities of waste coal fly ash and rubber tyres in north-east China, a new combined thermal insulation layer consisting of extruded polystyrene (XPS) board and modified soil (silty clay modified with fly ash and crumb rubber) is proposed. Field tests on an insulated test section and an uninsulated control section were designed to assess the thermal performance of the sections over the change of time and depth. The thermal characteristics and the effect and mechanism of the layer were investigated. Finite-element analysis was used to evaluate its long-term performance. The results showed that the temperature regime of the subgrade varied regularly. The combined thermal insulation layer effectively protected the road surface from cold and heat erosion, elevating the freezing depth to the upper surface of the combined layer. Furthermore, the thermal insulation effect was greater for the combined layer than the use of XPS only. The finite-element analysis showed that the impact on cold resistance was more evident in the road shoulder and roadway centre than on the slope toe, and the layer will still perform normally after 50 years.