Conceptual performance model for deep in situ recycled pavements with cement and bitumen additives

Abstract

The purpose of this paper is to provide information regarding a conceptual performance model for Deep in Situ Recycled (DISR) pavements where both cement and either foamed bitumen or bitumen emulsion have been added to the mix. CSIR Transportek and the Gauteng Department of Transport and Public Works, are conducting Accelerated Pavement Testing (APT) on test sections that have been rehabilitated in situ with cement and either foamed bitumen or bitumen emulsion. During APT the behaviour of the pavement structure is monitored together with environmental parameters. Based on this information, and associated laboratory testing data, a model for the performance of these pavements is currently being developed. The model is currently based on the results of APT testing under relatively high tyre loads. Construction data and visual behaviour data add to a better understanding and definition of the model. Although the APT evaluation is destined to continue for some time, the initial results indicate very distinct performance-related issues. In the paper a description of the pavements, their construction and their environment are provided. The initial APT and laboratory testing results are shown and discussed. A conceptual performance model based on the available results is proposed.