Impact of Clay Contamination on Rutting Performance of Asphalt Mixes

Sharmila Afsha, University of Texas at El Paso


Sustainability of asphalt mixtures can be improved by using natural sands. They can enhance workability and lower the amounts required for asphalt binder and manufactured fine aggregate of mixes. However, one of the primary concerns with incorporating natural sands in a mixture is clay contamination. Harmful clays are chemically active particles that swell when exposed to moisture and reduce the bond between aggregate and asphalt binder. As a result, this study explores the effect of clay contamination on the rutting and moisture susceptibility of asphalt mixes. Twenty-one clay combinations of material passing the 0.075 mm (#200) sieve were selected utilizing inactive (i.e., calcium carbonate and dolomite) and active (i.e., bentonite and natural clays) fines, with performance ranging from good to expected failure. First, the clay combinations were classified according to their level of chemical activity using the Methylene Blue Value (MBV). The asphalt mixture specimens were produced by adding each clay permutation to a reference Superpave mixture. The compacted specimens' performance was assessed utilizing the Hamburg Wheel Tracking Test (HWTT) for rutting and moisture susceptibility. Finally, the mineral composition of the inactive and active clay materials employed in this investigation was determined using X-ray diffraction (XRD). The experimental results revealed that mixes containing clay combinations with an MBV greater than 6 mg/g are more prone to rutting and moisture damage. Furthermore, XRD analysis confirmed that the active clays employed in this study contained minerals that were adverse to asphalt mixture performance, such as sulfuric acid, quartz low, and microline.

Subject Area

Civil engineering|Sustainability

Recommended Citation

Afsha, Sharmila, "Impact of Clay Contamination on Rutting Performance of Asphalt Mixes" (2023). ETD Collection for University of Texas, El Paso. AAI30634884.