Abstract: The load-bearing ratio test was first proposed by the California Highway Administration in 1928 to compare the strength of the material when California conducted the asphalt pavement damage survey, also known as the California Bearing Ratio, which referred to as the CBR (California Bearing Ratio) test, which is used to test the extreme bearing capacity of the highway subgrade in an unfavorable state, which is one of the main parameters of pavement design. Now more and more road projects in China require the tested CBR values for the preliminary design. Under normal circumstances, the CBR value for clay is difficult to meet the construction requirements, and the subgrade soil needs the lime improvement treatment. In order to study the influence of lime content and different curing ages on CBR value, the representative subgrade soil material of a section of Wuhan-Dawu Expressway was selected for testing, and the influence of different lime mixing conditions of improved soil on CBR value was analyzed. The optimal lime mixing contents for the three groups of soil samples were determined, and the influence of different curing ages on the CBR value when the soil reached the standard value under the condition of certain lime mixing ratio.

Key words: Bearing Ratio, Improved Soil, Ash content, Curing Age