Effect of mineral fillers on mastic and mixture for porous asphalt

Abstract

Porous asphalt is known to have poor strength and durability due to open nature and large air voids that expose the structure to air, water, and clogging materials. This could lead to stripping and ravelling problems which contribute to rutting potential of porous asphalt. The addition of fillers has been identified to improve the adhesion and cohesion properties by stiffening the asphalt binder and enhancing the bond strength between binder-aggregate. This study aims to investigate the effect of different filler types on the rheological properties of mastics and performances of porous asphalt. Hydrated lime, cement, and diatomite with content of 2% were used as fillers. The morphology and chemical composition of fillers were identified using a Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray (EDX) analysis. Dynamic Shear Rheometer (DSR) was used to investigate the rheological properties of mastics through frequency sweep and Multiple Stress Creep Recovery (MSCR) tests. DSR results indicated that the use of filler increases the stiffness of mastics. The MSCR test showed that hydrated lime and diatomite mastics exhibit the lowest non-recoverable compliance and high recovery compared to original PG 76 binder and cement mastic. The performances of porous asphalt were evaluated using permeability, abrasion loss, resilient modulus, and indirect tensile strength tests. All mixtures were found to show high permeability rate between 0.276 and 0.250 cm/s. Mixtures with hydrated lime showed lower abrasion loss of 21.5% compared to mixtures with cement and diatomite. In addition, the use of diatomite increases resistance of the mixtures to rutting and moisture damage compared to other fillers as shown by the enhanced resilient modulus and indirect tensile strength.