Selection of a technique for rehabilitation of asphalt pavement rutting is dependent on the geometrical extent of damage, and whether it is limited to the asphalt bound layers or reaching the subgrade. Overlays are not suitable when the distress is limited to the truck lane of multi-lane divided roadways. Rut-fillers are also not suitable when rutting is associated with heaves causing changes in the original profile of the pavement cross section . Milling of the damaged surface becomes a necessary part of the rehabilitation process for those above circumstances . The thickness of milled layer has to be rationally designed . The milled layer has to be replaced by a recycled or new rut resistant layer . This paper presents a study in which the main objective was to determine the thickness of milled layer that has to be replaced for the rehabilitation of pavement rutting. The procedure presented is applicable only for rutting limited within asphalt concrete layers. Full depth full width saw cut trenches together with full depth full width continuous cores were taken from the truck lane of ten rutted pavement sections . Profiles of asphalt concrete layers were used to determine the vertical extent of damage. In addition, the mean and standard deviation of rut depth and rut width along those ten pavement sections, were computed. A straight edge was used to measure the rut depth and the rut width (crest to crest distance).Simple relationships were developed relating the vertical extent of damage (thickness of milled layer) to the amount of rut depth and rut width It was concluded that the thickness of the milled layer that has to be replaced for the rehabilitation of pavement rutting should not be less than double the average rut depth or 5 % of the average rut width, along a pavement section . (A)
Abstract