USING FIBER-REINFORCED POLYMER LOAD TRANSFER

Abstract

Jointed concrete pavements require dowels to transfer the loads across transverse joints and to prevent faulting. The most commonly used dowels are made of epoxy-coated steel with a diameter ranging from 25 to 38 mm. Problems associated with dowels include corrosion of the dowel material and possible crushing of concrete surrounding the dowel causing looseness of the joint and faulting. The objective of this research is to evaluate corrosion-free alternatives to steel reinforcing elements. The use of Glass Fiber-Reinforced Polymers, GFRP, as load transfer devices is investigated and some material characteristics and design guidelines for GFRP dowels are introduced. In the experimental program, two types of dowel construction are tested. The first type is a round GFRP dowel bar having a 38-mm diameter and the second is a concrete-filled GFRP pipe having a 60-mm outside diameter. Laboratory testing and a field implementation project were carried out. The field test section was constructed on a regional highway in the city of Winnipeg and involved three types of GFRP dowels in addition to epoxy-coated steel. Falling Weight Deflectometer (FWD) testing was conducted after one year of service and showed that GFRP dowels produced 30% higher deflections compared to steel, however the load transfer efficiencies for GFRP dowels remained excellent. The use of GFRP dowels opens tremendous opportunities for optimizing dowel design and pavement performance. The increased diameter and reduced stiffness of the GFRP dowels results in lower bearing stresses between the concrete and dowel, which are major causes of dowel looseness and slab faulting.