Prepared in cooperation with the Indiana Department of Transportation and Federal Highway Administration. AbstractThe research involved evaluating three surface cracked pavements during 2002 and 2003. A 500m section of I-65 North of Lafayette was chosen as the first site (designated as Site 1), an I-65 section in downtown Indianapolis was the second site (Site 2), and US-421 in Madison was the third site (Site 3). Site 1 had 11-year old pavement, Site 2 had 12-year old pavement and Site 3 had 4.5-year old pavement. All these sites exhibited longitudinal wheel path cracking which was later identified as top-down cracking. All sites had excellent structural capacity indicating that the top-down cracking was confined in the pavement surface. This was confirmed by visual inspection of cores. The causes for top-down cracking in the surface layer were identified as follows: 1) non-uniformities in the material properties caused by construction practices such as segregation; 2) high in-situ air void content; 3) low amount of fines in mixtures, and 4) aging of binder. However, the study was not able to identify/verify any structural causes for top-down cracking.17.

Town in 1965, following which he was employed by the Provincial Government of the Cape Province as engineer in their Roads Department. From 1982 he was Chief Executive Officer of the Southern African Bitumen Association (SABITA) until his retirement in 2006. Since then he has acted as specialist consultant in pavement and materials engineering. He is a Fellow of the South African Institution of Civil Engineering, as well as of the Society for Asphalt Technology. His other interests include music and wildlife photography.

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