Experimental investigations and constitutive modeling of bitumen stabilized mixtures

Recycling of pavement is an effective way of rehabilitation of distressed bituminous pavements and in that context, recycling with bitumen stabilized material is gaining importance worldwide. Bitumen stabilized material consists of a mixture of pulverized bitumen coated aggregate particles mixed with fresh aggregate particles, water, foamed binder and active filler. Immediately after construction, the bitumen stabilized material has 15% air voids and due to traffic loading, the material densifies further. Also, due to the interaction of the various constituents during loading, the response of the material ranges from a granular material to a bituminous material. This of course depends on the temperature during testing and the density of the material. Most of the current investigations carried out on this material have focused their attention on determining appropriate ‘modulus’ value for use in pavement design and a rigorous constitutive modeling has not been put in place. In this present study, the mechanical response of the material at different air voids, cement content and temperature was investigated using strain controlled tension and tension–compression tests. It was found that the material exhibited viscoelastic behavior for all combinations of air voids, cement and temperature. A non-linear viscoelastic constitutive model was developed using a framework based on multiple natural configuration. A viscoelastic fluid model was used to predict the response of the material at 45°C and at 15°C, a viscoelastic solid model was used.