Effects of diatomite as filler on the porous asphalt mixtures properties

Abstract

Diatomite is a kind of mineral containing high amorphous silica content which is a very durable substance. Due to its useful characteristics such as lightweight, high porosity, high surface area, low density and high absorptive capacity, diatomite is identified with potential to be used as a filler to improve the performance of asphalt mixture. Porous asphalt is known to have poor strength and durability due to its open structure and high air void contents which exposed the structure to air and water. These factors may influence the adhesive strength of binder-aggregate and lead to cohesive failure within the binder film, which contribute to stripping and moisture damage. The addition of fillers has been identified to improve the adhesion and cohesion properties by stiffening the asphalt binder and enhance the bonding strength between aggregate and binder. Therefore, this study was undertaken to evaluate the potential of diatomite as filler in porous asphalt mixtures and compared with ordinary Portland cement. Field Emission Scanning Electron Microscopy (FESEM) was conducted to investigate the microstructure of the fillers. The compacted samples of porous asphalt mixture with Malaysian aggregate gradation were prepared using Superpave gyratory compactor at the target air voids content of 21%. Each sample was incorporated with 2% of filler and polymer modified binderof PG76 as a binder. The sampleswere then tested for abrasion loss, resilient modulus and indirect tensile strength. The test results show that the samples prepared with diatomite havelower abrasion loss compared to those with cement. Besides, the samples incorporating diatomite show enhanced resilient modulus and indirect tensile strength. Thus, these indicate that the diatomite filler has good potential to improve resistance to stripping and moisture damage compared to cement.