Test Study on the Feasibility of Filling Expressway Subgrade with Carbonaceous Mudstone

Abstract

Abstract The feasibility of using carbonaceous mudstone as expressway subgrade filler is studied through laboratory test. Firstly, the influence of overburden soil pressure on the strength change and argillization of carbonaceous mudstone during seasonal wetting and drying cycles is studied. Test results show that Serious argillization occurs when carbonaceous mudstone immersed in water; the overburden soil pressure can partially inhibiting the swelling deformation, strength reduction and argillization of carbonaceous mudstone; California Bearing Ratio (CBR) of the carbonaceous mudstone increases as the overburden soil pressure increase, but gradually decreases as the number of wetting and drying cycles increase and become stable after 6 cycles, and the stable value of CBR doesn’t meet the requirements of the roadbed and upper embankment, but meets the requirement of the lower embankment; the carbonaceous mudstone studied in the test could be directly used as the lower embankment filler, but could not be directly used as the roadbed and upper embankment filler. Secondly, experiment of improving carbonaceous mudstone by cement is conducted, and results show that the CBR of carbonaceous mudstone improved with cement meets the requirements of the roadbed and upper embankment, and cement-improved carbonaceous mudstone is suitable for filling the expressway roadbed and upper embankment.