Considerations for ensuring the durability of chemically stabilised road materials

As the scarcity of good-quality materials for the construction of roads and the demand for recycling of existing pavement structures increases, the use of chemical stabilisation is becoming more frequent. However, it is essential to ensure that the long-term durability of the stabilised material is sufficient to provide the structural capacity required over the design life of the road. Experience gained in South Africa over the past 25 years has shown that many failures of stabilised materials are the result of a lack of understanding of fundamental processes related to materials and stabilisation, which can be overcome by better training and implementation of existing knowledge. Carbonation of stabilised materials is a particular problem that needs to be assessed. This paper discusses various problems, with proposed solutions based on the evidence of many years of laboratory and field investigations in an attempt to ensure the optimum durability of stabilised layers and to provide a source of material for a better understanding.