NEW YORK'S EXPERIENCE WITH PLASTIC-COATED DOWELS

Because of past difficulties with joint supports in concrete pavements, New York began an investigation of plastic-coated dowels in 1972. This paper describes the construction and early performance of 5 pavements built to satisfy 3 major objectives: first, to identify construction problems related to the dowels; second, to determine if uniform joint movements are maintained; and, third, to determine the long-range corrosion resistance of the dowels. The plastic-coated dowels evaluated have a 2-layer coating of 4 mils (0.1 mm) of asphalt covered by 17 mils (0.4 mm) of polyethylene; they were welded or clipped into basket assemblies and staked to the subbase before paving with a slipform paver. Construction evaluation consisted of observing installation, checking alignment and coating damage, and noting joint cracks after paving. Six dowel samples were removed from the completed pavement for laboratory testing. Joint movement and pavement cracking have been monitored for up to 2 years. Observations and measurements during construction indicate that assemblies of plastic-coated dowels were easy to install and provided satisfactory control of joint crack formation. Some problems with dowel misalignment, damaged coatings, and slippage of coatings off the dowel ends were observed, but these are not considered serious inasmuch as they can be corrected. Performance observations indicate that joints are moving uniformly in all 5 pavements, and no distress has appeared that can be related to the dowels. Based on these observations, plastic-coated dowels show promise as transverse joint load-transfer devices for heavy-duty portland cement concrete pavements.