Effect of vegetable oil additives on binder and mix properties: laboratory and field investigation

Abstract

The effects of vegetable fluxes on the rheological properties of binders and foamed warm mix asphalt (WMA) have been studied. The fluxes consist of two organic additives: a methyl ester of fatty acid from sunflower and a resin fluxed with monoalkyl esters. Commercially, they are named Oleoflux and Green Seal, respectively. Three additives’ contents (0, 0.5 and 5 %) have been investigated. The surface tension, infrared spectra, viscosity, penetration and softening temperature of the binders have first been first measured. The linear viscoelastic properties of the mixes and binders have been studied through the complex modulus and modeled by the improved Huet-Sayegh model. The viscosity and complex modulus of the fluxed binders show that the increase of the additive content rejuvenates the base bitumen. The model parameters show that the relaxation times vary inversely with the additives’ contents. Moreover, after 8 months of aging at room conditions, it was found that the fluxed binders are more sensitive to aging than non-fluxed binders. In conjunction with the binders’ property characterization, the complex modulus and stripping resistance of the mixes have been studied. The mixes' complex modulus results are consistent with those of the binder. Thanks to an ingenious road built with WMA and HMA, the field performances at the early age when the road was built and 5 years later have been compared, although 5 years is not enough to draw definitive conclusions. No significant difference is found between WMA and HMA skid resistances and complex moduli. A slight decrease is found in the stripping resistance of WMA compared to those of HMA. A decrease in the skid resistance is observed 5 years later because of the polishing of the aggregates on the road surface due to traffic.