Failure of a cape seal in Karoo conditions and rehabilitation thereof

Abstract

Paper presented at the 21st Annual South African Transport Conference 15 - 18 July 2002 "Towards building capacity and accelerating delivery", CSIR International Convention Centre, Pretoria, South Africa.

This paper reports on the investigation by Messrs Potgieter, Hattingh & Raspi into the structural and functional condition of National route N1-11 between Hanover and Colesberg. This section of road is situated in the Karoo semi-desert region where summer and winter temperatures are extreme and the Weinert-N volume is above 10. The existing pavement was found to be structurally adequate with sufficient structural capacity for the next 10 – 15 years. However, the functional aspects of smoothing of the surface have deteriorated to unacceptable levels. The smoothing of the surfacing was found too severe and extensive. Over 88 % of the length of the old Cape Seal surfacing were smooth and bleeding. Aquaplaning and skidding because of substandard macro and micro surface texture depth has become a real problem. This deficiency of the road was classified as a surface only problem, normally rectified through the construction of a reseal. Several reseal designs were performed and the best product selected. This paper discusses the failure mechanism, design models as well as the construction of the reseal.