Deep strength asphalt pavements comprising a cement treated sub-base and thick asphalt base have been constructed in urban areas of Victoria for about 25 years. The paper presents a brief history of the development of the design methodology, some construction aspects and field performance data for 14 deep strength asphalt pavements constructed between 1971 and 1995. This type of pavement is now the most common type of urban heavy duty pavement constructed in Victoria. The paper covers the evolution of the design procedures from an empirical procedure using granular equivalency coefficients to a full mechanistic procedure as greater knowledge of the structural properties and performance of pavement materials became available. A range of standard asphalt mix types has evolved aimed at optimising the content and class of binder used depending on what structural qualities are required for each layer of pavement. The use of plant mixed cement treated sub-base in deep strength asphalt pavements has also proven to be a key factor in the success of these pavements. The stiff sub-base provides a sound working platform over relatively weak sub-grades and significantly extends pavement life for minimal cost. The introduction of "Design and Construct" contracts has opened the way for innovative pavement designs to be put forward and the paper discusses the main issues associated with this process. A summary of further development work required is also given. (A)
Samenvatting