Evaluation of alternative dowel bar materials and coatings

This study provided for a continuation of the long-term performance evaluation of 1.5-in (38-mm) diameter FRP dowels and Type 304 stainless steel solid dowels or mortar-filled tubes compared to epoxy-coated dowels. This primarily included an evaluation of load transfer efficiency (LTE) based on FWD testing, but also included a limited evaluation of faulting and ride. In addition, some FWD testing and coring was conducted on older projects (15 to 30+ years old) to evaluate the long-term corrosion protection provided by epoxy coatings. The 1.5-in (38 mm) FRP dowels with polyester resin and E-glass exhibited generally low LTE values, and are not providing performance comparable to that of the 1.5-in (38-mm) epoxy-coated mild steel dowel bars. The evaluation of alternative stainless steel clad dowels and concrete filled stainless steel tubes or pipes (Type 304 or Type 316) was inconclusive due to the small sample and the relatively short (14 years maximum) evaluation period, but it appears that they will perform satisfactorily in excess of 30 years given the minimal deterioration observed. Based on the coring of the older pavement projects, the life of the epoxy coating on mild steel dowels evaluated in Ohio and Wisconsin appears to be in the 25 to 30-year range. Many of the epoxy-coated dowels retrieved from in-service pavements revealed that the epoxy coating was debonded from the mild steel dowel and the surface of the mild steel dowel under the coating was pitted and rusted. In most cases, however, there was no significant loss of cross section. A review of two older projects in Ohio constructed with plastic-coated dowels indicated that those dowels were in excellent condition after 33 years. The overall condition of these projects was also very good, with little if any visible joint deterioration. Because plastic-coated dowels are similar to epoxy-coated dowels in terms of costs, they appear to be a cost-effective alternative to conventional epoxy-coated dowels.