The results of a field investigation conducted to determine the effectiveness of an automatic dowel bar inserter at properly placing dowel bars in rigid pavements are presented. The study, which was sponsored by the FHWA demonstration projects division, was conducted during February and March 1987 along a section of I-45, south of Dallas, Texas. A commercially available radar system, capable of quickly and easily locating reinforcing bars and other embedded steel in concrete, was used to examine the experimental dowel placement. This system produces a realtime graphic recording that gives both location and relative depth of the embedded steel. Cores were taken to calibrate the graphic recordings so that the actual embedded depths of the steel bars could be obtained. Along one portion of the test section, a dowel bar inserter was used to place dowel bars in the plastic concrete. For the remainder of the project, dowel basket assemblies were used to place dowels at transverse joints. The radar system was then used to evaluate dowel placement along 51 basket assembly and 52 inserter joints. Results indicate that dowel bar alignment at inserter joints is as good as or better than that at the basket assembly joints.
Samenvatting