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167405-1 Report Abstract

Coatings to Improve Low-Quality Local Aggregates for Hot Mix Asphalt Pavements

Min-Gu Kim, Joe W. Button, and Dae-Wook Park, Texas A&M University, November 1999, 80 pp. (167405-1)

A laboratory investigation was conducted wherein smooth, rounded, siliceous river gravel aggregates were coated with fine-grained polyethylene, carpet co-product, or cement + styrene butadiene rubber latex and used to prepare hot mix asphalt concrete specimens. Only the coarse (+ No. 4) aggregates were coated. The concept was that the coatings would enhance surface roughness of the aggregates and, thus, produce asphalt mixtures with superior engineering properties.

Hot mix asphalt specimens were prepared and evaluated using several standard and non-standard test procedures. Based on experiences during the coating processes and analyses of these limited test results, the following was concluded: All three aggregate coating materials increased Hveem and Marshall stability, tensile strength, resilient modulus (stiffness), and resistance to moisture damage of the asphalt mixture and reduced the energy required to achieve a given level of compaction. These findings are indicative of improved resistance to rutting and cracking in hot mix asphalt pavements fabricated using coated gravel aggregates in comparison to similar uncoated aggregates.

Keywords: Asphalt Pavements, Asphalt Mixtures, Aggregate Coatings, Cement, Latex, Carpet Co-Product, Marginal Aggregate

ENTIRE REPORT (Adobe Acrobat File – 934KBytes)