Hydrodemolition Partial Depth/Rebar Exposure

Hydrodemolition Partial Depth/Rebar Exposure

Hydrodemolition Partial Depth/Rebar Exposure

Rampart is an expert in the use of hydrodemolition for partial depth/rebar exposure removal of concrete having performed projects in 45 states, DC and Canada over the past 25 years.  Using 35,000-psi water pressure and 32-48 gpm, our hydrodemolition equipment quickly and effectively removes sound and unsound concrete from around the rebar.

Bridges, parking garages and other reinforced structures with chloride-contaminated concrete around the top reinforcing are good candidates for Rebar Exposure (Partial Depth Removal).  Significant levels of spalling and delamination indicate that the chloride content of the concrete has reached the threshold level required for the initiation of rebar corrosion.  Failure to remove this chloride-contaminated concrete from around the reinforcing will leave the structure at risk for long-term rebar corrosion and deterioration.  Best practices suggest that the chloride profile should be determined during the condition survey prior to specifying the repairs.  Concrete with chloride levels above the threshold level should be completely removed and the rebar exposed.  The deck is then overlaid with chloride-free concrete thus ensuring a durable, long-lasting repair.

Rebar Exposure/Partial Depth Hydrodemolition consist of:
  1. Rotomilling (optional to reduce cost) to remove the concrete cover (typically 1.5 – 2.0-inch);
  2. Hydrodemolition to remove all concrete to .75-inch below the bottom bar of the top mat of reinforcing (typically 2.5-4.5-inch);
  3. Vacuum cleanup of the debris and wastewater to provide a pour-ready surface;
  4. Placement of overlay or repair material.

While the entire deck surface can be hydrodemolished to expose the rebar (4.0-4.5-inch), it is generally more economical and quicker to rotomill the deck surface down to the top bar of the reinforcing.  This allows the hydrodemolition to perform the difficult task of removing the chloride-contaminated concrete from around the reinforcing.  In addition, hydrodemolition will remove the micro-fractures caused by the rotomilling, and provide a rough and bondable surface.

Bridges with minor spalling and delamination and low chloride content around the reinforcing are excellent candidates for Fast Track Bridge Overlay/Fast Track Hydrodemolition repairs.  Minor spalling indicates limited chloride contamination in the top reinforcing.  Replacing the wearing surface will significantly extend the bridge life.

Rampart uses high velocity waterjets with minimal water consumption (35,000-psi and 32-48 gpm).  The low water usage aids in the control and cleanup of the wastewater and eliminates the possibility of wastewater entering live traffic.  The low water consumption also helps to conserve 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.

Rebar Exposure/Partial Depth Hydrodemolition can also be used to repair substructures such as columns and beams as well as the slab soffit.