Experimental research on the mixed sand ratio and initial dry density of weathered sand improved expansive soil free load swelling rate

In this paper, through the indoor free load swelling rate test, expansive soil in a section of a first-class highway reconstruction project in Yichang City was studied. It emphatically analyzed the interrelations among free load swelling rate, non-load time, the proportion of mixed sand, and initial dry density. Experimental studies have shown that: free load swelling deformation is mainly divided into rapid expansion, slow expansion and final stability three stages; when the initial dry density is constant, free load swelling rate of the weathered sand modified soil will reduce rapidly before they slow down with the increase of sand proportion, weathered sand modified soil free load swelling rate is not sensitive to the large amount of sand mixed; in the same mixed sand ratio, weathered sand modified soil free load swelling rate increases rapidly with the increasing of initial dry density, there is a good linear correlation between them. To take appropriate control of the initial dry density during the expansive soil subgrade construction helps to reduce its swelling deformation and ensures the stability of the embankment.