PAVEMENT PERFORMANCE IN THE S12 ROAD EXPERIMENT, AN AASHO SATELITE TEST ROAD IN SOUTH AFRICA

Experimental sections of asphalt pavement totalling 2 km in length were incorporated during the construction of a heavily trafficked route between Johannesburg and Witbank with the object of assessing the suitability of various pavement materials and structures for carrying heavy traffic in the local environment. The experiment was planned as an AASHTO Road Test Satellite project to be used in an attempt to adapt the AASHTO Road Test findings to South African conditions. After two years of traffic, certain performance trends have become apparent. In particular, the early failure of a section with a cement-treated base, following the development of severe shrinkage cracking and pumping, has been closely followed. It is likely that at least 10 years will elapse before firm conclusions can be drawn on the performance of the remaining sections. In order to obtain earlier results from road experiments of this type, a completely automatic heavy-vehicle simulator has been designed and constructed which is a capable of applying 300,000 equivalent 80 kN axle load passes per day. The maximum wheel load is 80 kN, and the machine simulates the weaving action of normal traffic across the road. Initial obtained with the simulator on the experimental sections are reported.