Investigation of the performance of asphalt binder modified by sargassum

Abstract

Permanent deformations (rutting) are the most frequent problem throughout the world in the design of heavy- traffic pavement roads, which is a consequence of the accumulation of small amounts of plastic deformations occurring whenever a load is applied on the asphalt. This problem arises when the asphalt binders are prepared from hot asphalt mixtures. For this reason, asphalt modifiers are used to minimize failures, avoiding both permanent deformations and the subsequent cracks appearing on the pavements. In this study, seaweed Sargassum (SGZ) was used for the first time as a modifier of asphalt binders, as a response to the urgent need of finding a way to handle and take advantage of the massive amounts of this biomass, which has been found in recent years on the beach coasts of the equatorial Atlantic Ocean forming what the authors call the Great Atlantic Sargassum Belt. The rheological properties of these asphalt binders were evaluated by means of a DSR (dynamic shear rheometer) equipment; the results showed that the addition of sargassum at different concentrations (0.5–4% wt) increased the permanent deformation factor (G*/sinδ), and that higher elastic behavior is reached on the 2.5% SGZ sample. Additionally, the thermal resistance towards high temperatures was identified and compared with the control sample, observing the best results on the SGZ 2.5% sample. This behavior was confirmed by the calculation of the penetration index (PI). Moreover, the thermal stability test was efficient for demonstrating an improvement of the compatibility between the sargassum and the asphalt caused by a reduction in the difference between their densities.