Influence of diatomite filler on rheological properties of porous asphalt mastic

Mineral filler is usually added into asphalt mixture to stiffen the asphalt binder and improve mixture strength. This is particularly important for open gradations such as porous asphalt which is known to have poor strength and durability because of its open nature and large air voids. The interactions that occur between asphalt binder and filler results in certain mastic properties that affect the mixture strength. In this study, the effect of different types of filler on the rheological properties of asphalt–filler mastics for porous asphalt were evaluated using the frequency sweep and multiple stress creep recovery (MSCR) tests. Hydrated lime, cement and diatomite with 2% content were selected to produce asphalt–filler mastic. The influence of diatomite filler was investigated and compared to the hydrated lime and cement fillers. Results indicated that the use of filler increased the stiffness of mastics. The MSCR test showed that hydrated lime and diatomite mastics exhibited the lowest non-recoverable compliance and high recovery than the original PG 76 binder and cement mastic. Diatomite mastic exhibits the best resistance to rutting at high temperatures and stress levels, verifying that the use of diatomite filler is favourable because of its high temperature properties