The performance of an overlay to a jointed concrete pavement can be affected by the occurrence of reflection cracks above the joints. Reflection cracks are transverse and/or longitudinal cracks that occur in the overlay above the joints or cracks in the underlying concrete. If the cracks are not promptly treated and left to widen and propagate to the full depth of the asphalt layer, the subsequent influx of water can weaken the foundation and fines can be pumped to the surface creating voids beneath the base. In the most severe cases, the structure of the pavement is compromised to such a degree that movement of the pavement structure occurs under normal traffic loading. In some cases, the surfacing can also ravel back from the crack with the reduced lateral support, impairing the ride quality. If allowed to progress to this state the maintenance implications are more serious. This report summaries the performance to-date of a number of overlaid jointed concrete sites, with slab lengths varying from 5 m to 24 m, and various sites containing a lean concrete base. The treatments applied included: variations in asphalt thickness; use of polymer modified binders; crack and seat techniques; saw-cut and seal; inter-layers; and concrete joint treatments. Guidance is given in this report for jointed unreinforced (URC) and jointed reinforced (JRC) concrete pavements and flexible composite pavements with a cement bound granular material (CBGM) base. This guidance will assist the highway engineer in preparing maintenance design options, enabling the most cost-effective maintenance treatment to be selected, having regard to the existing construction and its current condition, the resources available and the required life of the pavement. (Author/publisher)
Abstract