Some Material and Construction Aspects Regarding in situ Recycling of Road Pavements in South Africa

In situ recycling as a pavement rehabilitation option in South Africa is becoming increasingly important. Use has been made of both bitumen (emulsion and foamed) and traditional chemical stabilizers (lime, cement, lime/slagment, etc). Very little detailed information regarding the effect of the in situ processing on the original material properties or the consistency of mixing and effectiveness of deep compaction has been reported. A project in which the shoulder and base of a national road were milled, mixed and replaced as a subbase with the addition of 2.5 per cent cement has recently been investigated. Testing of the material prior to and after recycling was carried out and the densities achieved after compaction were measured. This paper summarises the findings and conclusions from this project and highlights aspects that need better control during the in situ recycling operations.