Example of a PennDOT specification for hydrodemolition. Although PennDOT varies their hydrodemoltion specification per the circumstance, this is a good representation of their specification. (PennDOT has not endorsed this reproduction of their spec, but they should be fairly proud of it and not mind the use of it for the industry’s general knowledge).
ITEM 9100-0010:
CONCRETE BRIDGE DECK SURFACE PREPARATION USING HYDRODEMOLTION
DESCRIPTION
This work is bridge deck preparation using hydrodemolition to remove all unsound material. This item also includes the removal and disposal of all concrete and debris, vacuuming, shielding, water control, additional jack hammering, and all other aspects of work necessary to prepare the deck for the placement of the new latex modified concrete overlay.
Unsound concrete is defined as existing bridge deck concrete that is deteriorated, spalled, or determined by the Engineer to be unsound.
The requirement to provide a minimum 3/4″ clearance around all reinforcing bars that are more than 1/2 diameter exposed is waived, providing that the existing concrete is sound. The amount of steel exposed should be kept to a minimum.
The hydrodemolition equipment is required to be a computerized, self-propelled machine that utilizes a high pressure water jet stream to provide a rough and bondable surface while removing all unsound concrete and rust and concrete particles from an exposed reinforcement during the initial pass.
Pneumatic hammers not heavier than nominal 30-pound class, operated at no more than a 45-degree angle from horizontal, are to be used in areas that are inaccessible to the hydrodemolition equipment or in patching areas that require minor trim work to remove the remaining unsound concrete.
All construction debris, milling debris, and dust is to be completely removed from the bridge deck surface prior to calibration and commencement of the hydrodemolition surface preparation operation.
CONSTRUCTION
Perform hydrodemolition surface preparation over the entire top surface of the reinforced concrete bridge deck to provide a rough and bondable surface and to remove all unsound concrete during the initial hydrodemolition surface preparation pass. Remove any unsound concrete or original deck surface found after the initial hydrodemolition surface preparation pass at no additional cost to the Department.
Prior to the commencement of the hydrodemolition surface preparation operation, calibrate the hydrodemolition equipment on an area of sound concrete (7′ x 7′) as designated by the Engineer to demonstrate the desired result of this specification.
Move the hydrodemolition equipment to a second area (7′ x 7′) that is unsound as designated by the Engineer to demonstrate the desired result of this specification which is providing a highly rough and bondable surface and removing all unsound concrete during the initial pass.
If the equipment or end result is deemed unsatisfactory by the Engineer, remove the hydrodemolition equipment from the project site and provide another hydrodemolition unit for calibration. No additional contract time will be provided for this recalibration process if required.
Provide verification of the following settings to the Engineer:
- Water Pressure Gauge
- Sufficient water usage to remove all deteriorated and unsound concrete/material.
- Machine staging control (step)
- Nozzle size
- Nozzle speed (travel)
The calibration procedure specified is required each time hydrodemolition surface preparation is performed and as required to achieve the results specified.
Submit a plan for approval to the Engineer for control and filtering of all water discharged during operation.
Provide shielding, as required, to ensure containment of all dislodged concrete within the removal area in order to protect the traveling public from flying debris on, adjacent to, and below the work site.
After the hydrodemolition surface preparation operation has completed the initial pass, and the deck is dry and frost free, resound the deck to ensure that all unsound material has been removed. Remove unsound materials detected by the Engineer by pneumatic hammers (not heavier than 30 pound class) or by hydrodemolition at no additional cost to the Department. Remove any existing unsound patching material or existing unsound overlay material that is not removed during the initial hydrodemolition surface preparation pass incidental to this item of work.
Clean the hydrodemolition and milling debris with a vacuum system equipped with fugitive dust control devices and capable of removing wet debris and water all in the same pass. Blow dry the deck with air to remove excess water. Perform cleaning in a timely manner, before debris and water is allowed to dry on the deck surface. Remove any material allowed to dry prior to sounding at no additional cost to the Department. Splice or replace any reinforcing steel damaged or dislodged by these operations, with the same size bar, at no additional cost to the Department.
Provide a non-working technical field representative on the project site during the calibration and the hydrodemolition surface preparation operation.
MEASUREMENT AND PAYMENT
Square Yard of deck area regardless of the number of passes.
