In May 2012, discussion was initiated to eliminate the daily repair and re-repair of a heavily-used bridge near Lindley, N.Y.
The expansion of a nearby shale gas project had increased truck traffic on the wood-base bridge, which had a surface of hot mix asphalt with daily repair. Material shoving and rutting resulted in frequent complaints and re-repair. The downward slope approaching the bridge creates severe loading and decelerating forces that transferred through the HMA surface to the supporting timbers. Repair crews were at the bridge daily during the summer months, tying up limited resources, crews and traffic.
To identify a permanent solution, three repair options were demonstrated. All three were designed to identify the optimum balance between surface durability and supporting timber flexibility.
The repair materials were installed May 9, 2012. Pictures taken before as well as throughout the demonstrations documented their performance, providing a reference for material comparison. The repair options included full-depth Unique Paving Materials’ UPM Permanent Repair Material, 4-5 inches; CPM-DOT full-depth concrete patching material, 4-5 inches; and a combination, concrete on wood timbers topped with UPM, 2.5 inches each.
Products and Methodology Tested and Evaluated
- UPM Permanent Pavement Repair Material, the original asphalt permanent repair material since 1959, is designed to fix potholes permanently.
Unlike most cold patch products that have no inherent engineered design chemistry, UPM is formulated to the specific characteristics of the aggregate being used and stringently manufactured by UPM to bond and adhere both to itself and the road cavity it is correcting.
- CPM—DOT, a product of Unique: A concrete patching material specifically designed to develop a permanent bond with existing concrete. Fast-setting, it has high early strength, resists chlorides and provides superior freeze-thaw resistance.
- CPM-DOT base with UPM overlay.
Performance Observations, May 20, 2012
UPM full depth achieved 100 percent success with no pushing, shoving, spalling, rutting or loss of material.
Full-depth CPM-DOT mix initially cracked on small section onto the steel bridge expansion. The rest of the area held out 100 percent with no movement of test material, no shoving and no loss of material.
CPM-DOT concrete base with UPM overlay performed equal to the full depth UPM. The repair experienced no movement or loss of material. The test section kept its shape and remained intact. The condition of the concrete below the UPM was not inspected but was assumed acceptable due to the quality of the UPM surface layer.
On Sept. 19, Marc Stocum, Lindley highway superintendent, and Tony Guizzotti of UPM Unique Paving Materials Corp., met at the site to further inspect and evaluate the ongoing performance of the repairs. Stocum stated that the material was exceeding his expectations and that he was very pleased with the results of the three test products.
The CPM-DOT concrete test repair met the time test period, but was later removed due to cracking caused by the flexible wood substrate and the rigidity of the concrete. Interestingly, due to Stocum’s desire to deplete some remaining inventory on hand, he used a competitor’s product that frequently failed and had to be replaced with UPM.
The full-depth UPM is functioning well with no signs of spalling or rutting. Furthermore, the full-depth UPM installation is the lowest cost of the methods evaluated, including equipment costs saved as well as costs associated with time and labor avoided. This was the solution preferred and selected. The originally-installed UPM remains in place, and the daily repair and re-repair process for the Lindley maintenance crew has been eliminated by a “once and done” solution.
Information provided by Unique Paving Materials Corp.