Provisional results from accelerated testing of ultra thin-layer reinforced concrete in South Africa

Abstract

The CSIR Built-Environment, in conjunction with the University of Pretoria and the Cement and Concrete Institute of South Africa, developed a low cost option for the upgrading of unsurfaced (gravel) roads. The proposed solution is the placing of a thin layer of normal concrete reinforced with 5.6mm diameter steel with a mesh grid size of 200mm. This thin layer is placed on top of the existing unsurfaced road with minimal preparation to the existing road surface using labour intensive construction methods. Through full-scale trials this type of upgrading proved to be adequate for low-volume traffic applications (e.g. residential streets) as well as for higher-volume applications (e.g. bus routes). During the trials test sections were subjected to a total of over 700,000 ESALs over a period of 5 years without showing any deterioration. In order to determine the structural capacity of this type of overlay full-scale heavy vehicle simulator tests were conducted. This paper summarizes the initial results from the accelerated pavement testing (APT) tests and is aimed at building confidence in the use of thin-layer CRCP, with cognizance being taken of the pavement structure, support conditions, construction, climate and traffic.