Relating resilient behaviour of compacted unbound base granular materials to matrix and interlock characteristics

Compacted unbound granular materials used in pavement bases present a complex elastoplastic behaviour under wheel loading. This behaviour was found to be influenced by numerous factors, but the effect of aggregate matrix and interlock is not yet fully understood in the available literature. A comprehensive resilient modulus laboratory study on 18 samples revealed significant variations of the effect of gradation, which are associated with the evolution in the frictional properties within the grain fractions. The results also emphasized the importance of matrix interlock and non matrix aggregate void-filling capacity.

► Grain-size distribution of unbound base granular materials as an effect on the resilient modulus. ► Changes in grain-size distribution modify the material matrix and matrix packing (or interlock). ► Material frictional properties evolves through materials’ granular fractions. ► A granular packing quantification method like the Bailey method can be used to better understand materials’ behaviour. ► Aggregate matrix, matrix packing, as well as matrix frictional and interlock properties influence the resilient modulus.