Volume 9, Issue 2 (February 2012)
Moisture and Rutting Resistances of Foamed Asphalt Mixtures Containing Recycled Coal Ash or Shingles With Moist Aggregates
The objective of this study was to evaluate the laboratory moisture and rutting susceptibility of foamed warm mix asphalt (WMA) mixtures containing moist aggregates and recycled materials such as manufactured roofing shingles and coal ash material. The test properties of these mixtures included the indirect tensile strength (ITS), tensile strength ratio, flow value, and rut depth of dry and wet specimens. The experimental design included two percentages of coal ash (10 % and 5 % by weight of the aggregate), two shingle contents (5 % and 3 % by weight of the aggregate), foaming WMA and control mixtures, and two aggregate sources (containing approximately 0.5 % moisture). A total of 24 mix designs were used in this study. The test results indicate that the aggregate source significantly affected the moisture and rutting resistance, regardless of the foaming technology and/or recycled material type. In addition, the dry and wet rut depth values of mixtures containing moist aggregate generally satisfied the demand of pavement performance without requiring additional treatment. Moreover, all mixtures have high dry and wet ITS values as using recycled shingle and coal ash materials along with hydrated lime or liquid anti-stripping additive. Furthermore, the utilization of recycled coal ash and roofing shingles significantly improved the moisture and rutting resistance of WMA mixtures.