Fast Track Bridge Overlay
Total Surface Hydrodemolition
Rampart is an expert in Fast Track Bridge Overlay preparation, Fast Track Hydrodemolition, and Total Surface Hydrodemolition having performed projects in CT, MO, NC, OH, PA, VA, and WV. Rampart has been performing hydrodemolition for more than 25 years using 35,000-psi water pressure and 32 gpm. Our hydrodemolition equipment quickly and effectively removes unsound concrete and provides a rough and bondable surface. Fast Track Hydrodemolition is used primarily to remove and replace the wearing surface (concrete cover) on bridge decks. Using Rampart’s Fast Track Hydrodemolition, a bridge surface can be quickly prepared for a concrete overlay. Using rapid-set concrete, the overlay or repair material can be placed and the bridge re-opened to traffic each day. Weekend closures starting at 9p Friday to 6a Monday allow larger bridges to be overlaid with minimal disruption to the traveling public.
Fast Track Hydrodemolition consist of:
- Rotomilling to remove the concrete cover (typically 1.5 – 2.0-inch);
- Scarification using hydrodemolition (Fast Track Hydrodemolition) to remove spalled and delaminated concrete (unsound concrete) and to provide a rough and bondable surface (typically 0.25 – 0.5-inch);
- Vacuum cleanup of the debris and wastewater to provide a pour-ready surface;
- Placement of rapid-set repair material or overlay.
For Fast Track to be “Fast”, the concrete cover must be removed by rotomilling and the overlay or repair material must be rapid-set concrete. Rotomilling and rapid-set material put the “Fast” in Fast Track Hydrodemolition.
Rotomilling removes concrete cover, while crushing and breaking up spalls and delaminations. This allows the hydrodemolition to quickly and easily remove any remaining “unsound” concrete. In addition, hydrodemolition will remove the micro-fractures caused by the rotomilling, and provide a rough and bondable surface. Since hydrodemolition removes very little material, it has been described as Fast Track Hydrodemolition. However, regardless of how fast the concrete is removed and the surface preparation completed, this repair method cannot work during weekend or weeknight closures without the use of rapid-setting concrete or repair material.
Bridges with minor spalling and delamination are excellent candidates for Fast Track Hydrodemolition. Minor spalling indicates limited chloride contamination in the top reinforcing. Replacing the wearing surface will significantly extend the bridge life.
Bridges with a significant amount of spalling and delamination or that have chloride levels above the threshold level in the top reinforcing may not be good candidates for this quick-fix method. Fast Track Hydrodemolition does not remove the chloride-contaminated concrete from around the reinforcing, and as a result, these bridges will remain at risk for long-term rebar corrosion and deterioration. We recommend establishing the chloride profile during the condition survey prior to specifying the repairs. Chloride levels above the threshold level for corrosion would indicate that the top reinforcing should be completely exposed (rebar exposure using hydrodemolition) to insure a durable, long-lasting repair.
Rampart uses high velocity waterjets with minimal water consumption (35,000-psi and 32 gpm). The combination of high-pressure and minimal water usage aids in the control and cleanup of the wastewater and minimizes the possibility of wastewater entering live traffic. Minimizing the water consumption helps protect this valuable resource.
In addition, Rampart uses high-capacity vacuum trucks, each containing a 10,000-psi water blaster, that quickly and effectively clean the surface following the hydrodemolition. Rampart’s vacuum trucks remove the slurry and debris from the surface leaving it in a pour-ready condition.
While the phrase “Fast Track Hydrodemolition” has gained in popularity, it would better be described, as “Fast Track Bridge Overlay” as the results of this bridge repair method is an overlaid bridge with a new wearing surface.