Evaluation of dowel bar alignment from a two-step dowel bar inserter

Abstract

Dowel bars are installed in concrete pavements using metal baskets or mechanical dowel bar inserters (DBIs). The latter can be accomplished in two ways: the traditional one-step process consisting of a slipform paver outfitted with an automatic DBI and an on-board vibrator, or a two-step process consisting of a DBI attached to the main paver and followed by a second paver that consolidates the holes left by the DBI. Several concerns have been raised regarding the dowel bar misalignment in the two-step paving process. The MIT Scan-2 device was used to evaluate the dowel bar misalignment in a concrete pavement constructed using a two-step DBI in Lake County, Ohio. The results revealed significant deviation in horizontal, vertical and longitudinal positions. Furthermore, many bars were found to be severely misaligned, increasing the possibility of joint locking. As a result, Ohio has banned the use of two-step DBIs on all Ohio Department of Transportation projects.