Effect of thickness of a sandwiched layer of bitumen between two aggregates on the bond strength: An experimental study

Abstract

Understanding bond between bituminous binder and aggregate is an important consideration for bituminous mixes. The cohesion within the binder and the adhesion between the binder and the aggregate interface, affect the mix performance in terms of load transfer, propagation of crack, moisture sensitivity etc. In the present work, bond strength between aggregate and bituminous binder while varying bitumen film thickness has been studied. The test temperature and the displacement rate have been kept fixed as 23±1oC and 1 mm per minute respectively. Polished surface of one aggregate is entirely covered with thin film of bitumen and then another aggregate is placed with its polished surface over the bitumen film. Vertical pulling load is then applied to this assembly. Load displacement data is recorded for various samples for different bitumen film thicknesses. The variation of peak stress, energy (toughness) are plotted with respect to the bitumen film thickness. The conditions for cohesion and adhesion failures are studied. It is envisaged that such studies would evolve as a useful input for the micro-mechanical modeling of bituminous mix. © RILEM 2012.