Long-Term Performance of Failed Flexible Pavements Stabilized with Cement

摘要

In recent years, there has been a shift in resources away from the construction of new roadway networks to the maintenance and rehabilitation of the secondary, low-volume roadways. The focus today is how to achieve a strong and durable pavement that is not only cost-effective but also utilizes less virgin materials and is environmentally sustainable. The repair of failed flexible pavements – which make up the majority of most systems – is often an expensive process, especially if the pavement has base or subgrade problems, and a simple overlay will not result in a long-term solution. This is often the case with low-volume roads, where minimum pavement structures are expected to carry heavy traffic and subsequently experience serious pavement deterioration. rnA procedure is available, called full-depth reclamation (FDR) with cement, which allows old deteriorated asphalt pavements to be recycled and stabilized with cement, creating a new base that will provide an excellent foundation for long-term pavement performance. The concept of recycling existing pavement materials is especially attractive in locations where quality aggregates may not be readily available. Instead of using new aggregate sources, the aggregates from the old pavement can be recycled, and with the addition of cement, the materials will form a much stronger base to improve the pavement foundation. rnRecent studies have shown that agencies have successfully used the FDR with cement process for well over 25 years, with little or no evidence of structural failure in these FDR sections. In fact, the distress identified on the pavement surface was restricted to the hot-mix asphalt overlays and was not a result of failures in these stabilized base layers. Additionally, agencies that use this process have reported cost savings between 30% and 60% over conventional reconstruction methods. Cost savings and environmental benefits result from use of existing pavement materials, reduced hauling associated with removing old materials and placing new materials, and from the longer expected life of a pavement with a cement-stabilized base. rnThis paper will include the engineering and construction steps involved in designing and building an FDR project, with examples of successful projects constructed over the last 25 years in a variety of challenging environments.