LONGITUDINAL WEDGE JOINT STUDY. FINAL REPORT

This report describes the results of a five-year study 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 which produces a 3:1 sloped face at the edge of the first bituminous mat placed. 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 and coring were 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 to the standard longitudinal center joint. These measurements indicate that the wedge joint has a more uniform density across the joint and has 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 to the motorist when making lane changes in construction areas.