Model for prediction of resilient modulus incorporating matric suction for recycled unbound granular materials

This paper presents experimental results on the effect of matric suction on the resilient modulus of four recycled unbound granular materials. The recycled materials were prepared at moisture contents ranging between 70% and 90% of optimum moisture content (OMC) and tested in a repeated load triaxial test (RLTT) apparatus under various stress regimes. Soil-water characteristic curves (SWCC) were established for each material by preparing samples at various moisture contents and measuring matric suction with filter papers. To obtain the wet end of the SWCC, further samples were conditioned on a tension plate at suctions controlled by the hanging water column method. Some published models for prediction of resilient modulus were applied to the experimental data, but the correlations were unsatisfactory generally, and so an improved model was sought. Subsequently, a model with four terms and six constants was developed, which followed the general power law. A single set of material constants was found for all recycled materials to provide satisfactory predictions of resilient modulus (R-2 = 0.88), over a wide range of stresses and moisture states.