Experimental Investigation of Bitumen and Mastics under Shear Creep and Creep-Recovery Testing

Abstract

This paper characterises binder and mastic behaviour under shear creep and creeprecovery tests. Although several researchers have investigated the creep and recovery behaviour of pure and polymer modified bitumen, there is a primary need to investigate the behaviour of mastic in such a way to better correlate with the behaviour of asphalt mixtures. The steady state condition under creep testing and recovery behaviour under creep recovery testing are characterised through testing in the dynamic shear rheometer (DSR) under a wide range of stresses and temperatures. 40/60 pen pure bitumen as well as binder-filler mastics containing limestone blended at three different concentrations [35%, 50%, and 65% by mass of mastic] were utilised for this study. Creep testing results indicated that pure bitumen and mastics behave linearly at low stress levels and nonlinearly at high stress levels. In addition, the stiffening effect of filler is characterised through a new Stiffing Factor. Stiffening Factor was determined for each bitumen-mastic combination obtained under similar testing conditions based on a steady-state curve fitting technique. Results analysis of creeprecovery tests showed that the recovery property of the bitumen is affected by both stress limit and filler concentration but insignificantly influenced by temperature. Moreover, the recovery property of bituminous material reduces with increasing filler content.