Impact of Nanoclays on Chemical Fractions and Mechanical Performance of Asphalt Binders

Abstract

Asphalt binder often is modified to obtain better performance of the pavement. Some recent studies have considered nanoclay as an alternative to currently practiced styrene-butadiene-styrene (SBS) modification to reduce the asphalt binder’s overall cost. This study evaluated any notable changes in the chemical composition of the binder due to the nanoclay modification and investigated any correlation between the chemical composition and mechanistic properties of the asphalt binder. It was found that changes in the chemical composition of nanoclay-modified binders are crude source–dependent. After nanoclay modification, the binders that originated from the Arabian crude were found to be more acidic than the binders from the Canadian crude source. However, nanoclays did not have any notable impact on the polarity of the tested asphalt binders regardless of their crude sources. The saturates, aromatics, resins, and asphaltenes (SARA) analysis results of asphalt binders revealed that the n-heptane insoluble contents increased notably after modification with nanoclays, whereas the saturates content decreased due to aging. Some mechanical properties (e.g., viscosity and rutting factor) were found to be correlated with n-heptane insoluble contents. Moreover, the sessile drop analysis test result showed that the nanoclay-modified binders offered superior bonding with gravel than with sandstone. Multiple linear regression analyses suggest that there is a fair (R2=0.55) correlation between the binders’ SARA components and compatibility for gravel.