Rehabilitation of heavy duty concrete pavements prediction of foamed bitumen mixtures

Abstract

Paper presented at the 20th Annual South African Transport Conference 16 - 20 July 2001 "Meeting the transport challenges in Southern Africa", CSIR International Convention Centre, Pretoria, South Africa.

In container ports pavements are subjected to ultra heavy wheel loads that may greatly exceed those of highway trucks, but often fewer repetitions are applied. These pavements are typically termed heavy duty pavements. The heavy duty pavement at the Transnet Container holding area at City Deep, Johannesburg had been in service for about 20 years and it showed severe cracking. The pavement was still serviceable and in operation, but rehabilitation or rebuilding had to be done in order to prevent the pavement from becoming unserviceable. The pavement consisted of a 300mm concrete slab pavement and rebuilding of this pavement was an option, but it involved high expenditure. As the existing concrete pavement had severe block cracking, and in some areas even crocodile cracking, a concrete slab overlay would require a slab of substantial thickness to rehabilitate the pavement. Concrete-filled geocells has shown substantial promise for new concrete pavements under ultra heavy loading conditions (Visser, 1999) and it was decided to investigate the suitability of these cells as a rehabilitation measure. The geocells, known as Hyson-Cells, offer three-dimensional interlocking cast in-situ blocks. It further offers resistance to slew caused by turning movements of heavy vehicles as well as resistance to the point loads of stacked containers. Hyson-Cells differs from interlocking pavements in that it is cast in-situ and that interlocking takes place in a three dimensional direction. Models explaining the three dimensional interaction between the blocks are very complex and the structural and functional contribution of such an overlay can best be investigated by experimental techniques.