Rut Susceptibility of Large Stone Mixtures

Abstract

The rut susceptibility of large stone mixtures (LSMs) was evaluated from laboratory materials characterization tests that included compressive creep and recovery tests on LSMs and conventional base mixtures, and repetitive simple shear tests. Results from compressive creep and recovery tests on core samples are mixed. Although there are LSMs that exhibit improved rut resistance over conventional mixtures, this was not consistent for all comparisons made. This result may be due to differences in degree of stone-on-stone contact between the LSM cores tested. Data from repetitive simple shear tests also demonstrated the potential for generating additional confining pressures due to the tendency of the mixtures to dilate. While the additional confining pressure due to dilation would tend to reduce the compliance of a mix, test results indicate that allowing too much dilation will also not be beneficial in terms of rut resistance, thus, suggesting an optimum level of dilatancy.