Effect of cement-by-pass dust stabilized-expansive soil subgrade on pavement rutting

This paper investigates the potential use of Cement-By-Pass Dust (CBPD) to stabilize an expansive soil. The soil was treated by mixing CBPD in amounts of 6%, 9%, 15%, 20% and 30% by dry weight of soil. For comparison purposes, the soil was also stabilized with cement and lime. Cement and lime were added in 6% and 9%. The stabilized soil was subjected to an extensive laboratory testing such as Atterberg's limits, compaction, CBR and swelling tests. The results showed that the effectiveness of CBPD in reducing the plasticity index and the swelling potential of the expansive soil with comparable reduction as cement and better than lime. The optimum dosage of CBPD was found to be 15% where the swelling percent of the soil decreased from 11% for untreated soil to 3%. The CBR increased with the increase in CBPD content up to 15%. A typical pavement structure with the stabilized soil as subgrade was analyzed using Mechanistic-Empirical Pavement Design Guide model and finite element analysis. The effect of the stabilized subgrade on rutting of pavement was investigated. The rutting in the subgrade decreased from 2.9 mm for untreated subgrade soil to1.3 mm for the soil treated with 15% CBPD.