Experimental investigation on the combined effect of dowel misalignment and cyclic wheel loading on dowel bar performance in JPCP

Abstract

A number of previous studies indicated that the joint lockup due to misalignment and looseness of dowel bars may cause joint distress in Jointed Plain Concrete Pavement (JPCP). This article reports a detailed experimental investigation of pull-out load and joint lockup due to dowel misalignment; and dowel looseness caused by the combined effect of misalignment and cyclic traffic load. The test slabs were supported on steel beams with an appropriate amount of vertical stiffness so as to incorporate the effects of underlying layers of real pavements. The article also provides an experimental investigation to assess the suitability of Glass Fibre Reinforced Polymer (GFRP) bars as alternative dowel bars to reduce joint lockup and associated detrimental effects at the dowel-concrete interface compared with epoxy-coated steel dowels. The results show that the 38 mm GFRP dowels that have equivalent flexural rigidity (EI) to 25 mm steel dowels can withstand the cyclic traffic load, significantly reduce joint lockup and dowel looseness, and can provide adequate Load Transfer Efficiency (LTE). It was also observed that misalignment affects dowel looseness significantly more than the number of cycles for traffic load. The slab-base separation and orientation of misaligned dowels have significant effects on the load required to open the joint.