Marquam Bridge Repair: Latex-Modified- Concrete Overlay
TRANSPORTATION RESEARCH RECORD 1204 59 Marquam Bridge Repair: Latex-Modified Concrete Overlay and Joint Replacement JOHN D. HOWARD The Marguam Bridge in Portland, Oregon, provides a crossing CONDITION OF DECK AND JOINTS of the Willamette River for the north-south 1-5 freeway. After 17 yr of service, the bridge, which was opened to traffic in Prior to and after award of the contract, surveys were made 1966, had a badly worn deck and numerous deck expansion to determine the extent of work needed to be done. (Overlay joints in need of repair. The bridge has a daily traffic count contract was awarded May 10, 1983.) Both surveys found of approximately 86,000 vehicles. Because of lack of capacity of detour routes, complete closure to traffic could be permitted significant wear throughout the structure, with a number of only during night hours. To correct the deck and joint prob spans that had the top mat of reinforcing exposed and a num lems, a contract was awarded in May 1983 for a latex-modified ber of locations with loose angles at the joints (Figures 4 and concrete overlay and joint repair. On a previous job with a 3- 5). Based on the elevation of the armored corners at the joint, percent grade, the tendency of the finished surface to shift approximately 0.5-1 in. of rutting in the wheel tracks occurred downhill during the early cure stages was noted, and it was during the 17-yr life of the deck. Bridge plans showed 1.5-in. thought that this tendency could be a major problem on this cover on the top mat of reinforcing, which apparently was structure with ramps on 6-percent grades and 0.10 ft/ft supers.
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