Thermal Benefits of Low Solar Absorption Coating for Preventing Rail Buckling

A low solar absorption coating for rail application is developed to reduce the peak rail temperature and buckling risk in summer months. The proposed coating system provides a highly reflective surface through white or off-white color and has constituents to provide high abrasion resistance and self-cleaning properties. The zero volatile organic content (VOC) and one hundred percent inorganic coating system has excellent adhesion to steel surfaces with minimal surface preparation. This paper presented the outdoor temperature monitoring results of the coated rail segments under hot weather. The results show that the application of coating could significantly reduce the peak rail temperature up to 10.5°C. Three-dimensional finite element (FE) models were developed to predict temperature distributions and thermal stresses in the rail. The thermal stress simulation shows that, when the rail neutral temperature (RNT) is relatively low, rail coating decreases the compressive stress in the rail up to about 50% during the hottest hours. Although increasing the RNT decreases compressive thermal stresses in the rail, it could increase the risk of rail break due to the increased tensile stresses in the rail. The coating application could reduce the high RNT requirement during rail placement and prevent rail buckling as the effective RNT decreases after traffic and maintenance. Therefore, the low solar absorption coating could serve as a proactive way to control peak temperatures and thermal stresses in the rail.