A torsional hollow cylinder research apparatus for studying the permanent deformation characteristics of asphalt

A large, innovative torsional hollow cylinder apparatus has been designed and commissioned for research investigations on asphalt. It can apply the complex shear and normal stress paths experienced in a pavement under a moving wheel load. The resulting high-quality data on permanent shear and volumetric strains will assist with the development of theoretical methods for rut depth prediction and act as an accurate reference to assess the performance of simpler test equipment. A wide range of repeated load stress paths can be applied under constant temperature conditions. The 350 mm long test specimens have a wall thickness of 50 mm. They are produced by accurate coring from a roller compacted test slab of asphalt. A detailed description of the apparatus is presented along with some preliminary results.