Assessing recycled/secondary materials as pavement bases

The use of recycled or secondary materials in pavement construction is gaining popularity owing to the added advantages over conventional materials, which include the conservation of natural resources, conservation of energy, preservation of the environment and reduction in life-cycle costs. In this research, two types of recycled materials, namely reclaimed asphalt pavement and cement-stabilised quarry fines, were utilised as pavement base materials for a highway extension project in Arlington, Texas, USA. Prior to the construction of test sections, a series of laboratory studies including strength, compressibility, swell/shrink and resilient modulus tests were performed on the selected base materials to verify their suitability as base materials for pavement construction. Pavement test sections were instrumented with horizontal inclinometers and pressure cells to monitor the long-term performance of these new base materials. Pavement surface profiling surveys were also conducted at regular intervals to monitor for any accumulated roughness of the pavement surfaces. Analysis of results obtained from both laboratory and field monitoring studies demonstrates that these secondary materials can be effectively used as pavement bases. The sustainability issues of this project are also discussed in detail.