Experimental investigation of the pull-out behaviour of misaligned dowel bars in concrete pavements

Abstract

Dowel bars in Jointed Plain Concrete Pavements transfer wheel loads across transverse joints while permitting joint movement caused by temperature and moisture variations. However, improper dowel alignment during construction may restrain joint movement and generate stress concentrations within the surrounding concrete, leading to premature pavement distress. This study experimentally investigated the pull-out behavior of single dowel bars subjected to horizontal, vertical, and combined skew misalignments of 3.1° and 6.3°, representing the allowable tolerance limit and twice the tolerance limit, respectively. Pull-out tests were conducted on six concrete specimens using a manually operated loading arrangement, while load and displacement responses were recorded using a load cell and Linear Variable Differential Transformers (LVDTs). The results demonstrated that pull-out resistance increased with increasing misalignment magnitude. The control specimen exhibited the lowest pull-out load of 0.9 kN, while the highest pull-out load of 7.5 kN was recorded for the 6.3° vertical skew specimen. Visible cracking was observed near the dowel-concrete interface in the vertically misaligned specimens, indicating increased stress concentration caused by joint restraint. The findings demonstrate that dowel bar misalignment significantly influences pull-out resistance and crack development, highlighting the importance of maintaining dowel placement within specified construction tolerances to reduce the risk of premature pavement distress.