Integrated approaches for predicting soil-water characteristic curve and resilient modulus of compacted fine-grained subgrade soils

Abstract

This paper combines a series of approaches for predicting the soil-water characteristic curve (SWCC) and the variation of the resilient modulus (MR) of compacted fine-grained subgrade soils with moisture content, which is the key information required in mechanistic pavement design methods. The presented approaches for the SWCC and MRare integrated, as (i) they are developed following the same philosophy, (ii) they require only the measurements of the suction and moisture content or MRat saturated and optimum moisture content conditions for prediction, and (iii) the predicted SWCC is used for predicting the MR– moisture content relationship. Experimental studies have been performed on five fine-grained subgrade soils that were collected from different regions in Ontario, Canada, to determine their MRat various external stress levels and post-compaction moisture contents, as well as their SWCCs after the MRtests. Experimental measurements are predicted using the integrated approaches and the empirical approaches currently used in the mechanistic–empirical pavement design guide (MEPDG). It is demonstrated that the integrated approaches are easy to use and show improved reliability in predicting both the SWCC and MRfor the investigated subgrade soils in spite of using limited experimental data.