Longitudinal wedge joint study

A 5-year study was undertaken to develop a technique for producing more durable longitudinal construction joints in bituminous pavements. The construction procedure evaluated involves forming the joint between adjoining lanes as two overlapping wedges. The wedge joint is formed by a steel plate attached to the paver screed. The effectiveness of the wedge joint was measured by the extent to which this procedure was able to eliminate a density gradient across the joint. Nuclear density testing was undertaken to determine the uniformity of the density across the joint and, hence, the nature of the density gradient. Density measurements were taken across the wedge joint and compared with the standard longitudinal center joint. These measurements indicated that the wedge joint had a more uniform density across the joint and a higher average density than the standard joint. The wedge joint eliminates the density gradient and, hence, lowers the potential for joint deterioration. By eliminating the vertical edge, the wedge joint eliminates the vertical dropoff and offers a safer condition for motorists making lane changes in construction areas.