1039CONCRETE BRIDGE DECK SURFACE PREPARATION, HYDRODEMOLITION

HYDRODEMOLITION

1039.1DESCRIPTION—This work is bridge deck surface preparation after scarification using hydrodemolition

to provide a rough and bondable surface and to remove unsound concrete. This work includes the removal and disposal of concrete and debris, vacuuming, shielding, water control, jack hammering and chipping, and work necessary for preparing the deck for completing concrete bridge deck repairs and the placement of a new latex modified concrete wearing surface as indicated and directed.

1039.2MATERIAL—Not used.

1039.3CONSTRUCTION—

and approval for control and filtering of water discharged during the hydrodemolition operation. Include in the submission the maximum and minimum water pressure (pounds per square inch) and water usage (gallons per minute) the hydrodemolition machine will provide. Provide settlement basins or devices to allow only visibly clear water from leaving the project site. Protect scuppers, inlets, and downspouts from material that would cause plugging. Provide free flowing, unobstructed drainage structures at the completion of this operation. Provide a technical field representative on the project site during the calibration and the hydrodemolition surface preparation operation.

self-propelled machine that utilizes a high -pressure water jet stream to provide a rough and bondable surface while removing unsound concrete , rust and concrete particles from exposed reinforcement during the hydrodemolition operation.

1.a Calibration. Completely remove construction debris, scarification debris and dust from the bridge deck surface before calibration. Calibration is required each time hydrodemolition surface preparation is performed and as required to achieve the results specified. Before commencement of the hydrodemolition surface preparation operation, calibrate the hydrodemolition equipment on an area of sound concrete (7 -foot x 7-foot) as designated by the Structure Control Engineer to demonstrate that the hydrodemolition equipment can provide a rough and bondable surface. Calibrate hydrodemolition equipment to remove no more than 1/4 inch of concrete (original deck surface to peaks of roughened surface) in sound areas. Move the hydrodemolition equipment to a second area (7-foot x 7-foot) that is unsound as designated by the Structure Control Engineer to demonstrate that the hydrodemolition equipment can provide a rough and bondable surface while removing unsound concrete in one pass. Adjust the settings as required within the limits established below to achieve total removal of unsound concrete. Provide verification of the following settings to the Representative:

• Water pressure gauge (psi)

• Water usage (gpm)

• Machine staging control (step)

• Nozzle size

• Nozzle speed (travel)

The hydrodemolition surface preparation production may begin after the Structure Control Engineer accepts the calibration and production settings. Maintain and provide the calibration and production settings to the Representative before and during hydrodemolition surface preparation production. If unsatisfactory results are obtained, stop hyrodemolition until the equipment deficiency or malfunction is corrected. Provide another hydrodemolition unit for calibration if onsite equipment deficiencies cannot be corrected at no additional cost to the Department. No additional contract time will be provided for equipment deficiencies, malfunctions or recalibration of another hydrodemolition unit if required.

coverage is insufficient, use pneumatic hammers not exceeding 30 foot-pounds, operated at no more than a 45-degree angle from horizontal. Hand held water blasting equipment capable of delivering a minimum of 25 gpm at 10,000 psi are also allowed. Use chipping hammers not exceeding 15 foot-pounds or handheld water blasting equipment when removing concrete within one inch of the reinforcement steel.

of dislodged concrete within the removal area to protect property and the traveling public from flying debris on, adjacent to, and below the work site. Perform scarification as specified in Section 1041 on the bridge deck before hydrodemolition. Remove construction debris, scarification/milling debris, and dust completely from the bridge deck surface before commencement of the hydrodemolition surface preparation operation.

bridge deck or locations indicated to provide a rough and bondable surface and to remove unsound concrete in one pass . Verify and document removal every 30 feet along the cutting path. Do not allow vehicles other than approved construction equipment on those sections of deck where hydrodemolition has begun. Prevent contamination of the deck by providing protection for hydrodemolished portions of the deck. Stop the surface preparation operation if it is determined that sound concrete is being removed in excess of 1/4 inch (scarified deck surface to peaks of roughened surface in sound areas) or unsatisfactory results are being obtained, as determined by the Representative. Perform recalibration or changes in equipment and methods before resuming the operation.

control devices and capable of removing wet debris and water in the same pass. Cleaning includes but is not limited to fine material, powder, dust, water, and particles in pockets, voids, and crevices that would hinder an overlay from bonding with the substrate. Use oil-free compressed air to remove excess water and to dry the deck . Perform cleaning before debris and water dries on the deck surface. Remove material allowed to dry at no additional cost to the Department.

performed and the deck is dry and clean, resound the deck to ensure unsound material has been removed except Type 3 concrete bridge deck repair removal areas . Perform the remaining removal for Type 3 concrete bridge deck repair areas as specified in Section 1040 and as directed . Unsound concrete is defined as existing bridge deck concrete that is deteriorated, spalled, or determined by the Representative to be unsound. Remove remaining unsound concrete, patching mate rial, or existing unsound overlay, as determined by the Representative, with pneumatic hammers or hydrodemolition at no additional cost to the Department. Use pneumatic hammers to provide a rough and bondable surface in areas that are inaccessible to hydrodemolition equipment. Remove unsound concrete or original deck surface found after the hydrodemolition surface preparation operation at no additional cost to the Department.

Splice or replace reinforcing steel damaged, bent, or dislodged by the hydrodemolition operations with the same size bar at no additional cost to the Department. Repair reinforcing steel distorted as a result of contractor operations at no additional cost to the Department. Remove portions of heavily corroded reinforcement steel where less than 1/2 of the effective cross-sectional area remains. Replace with the same type and size of bars as specified in Section 1002.3 and as directed.

The requirement to provide a minimum 3/4-inch clearance around reinforcement bars that are more than 1/2-diameter exposed is waived, provided the existing substrate concrete is sound. Where more than 1/2 diameter of the reinforcement bar is exposed, and the bar is corroded around the circumference , adjacent concrete is rust stained, or the bar is debonded from the substrate concrete , chip away concrete or water blast to provide a minimum 3/4-inch clearance.

1039.4MEASUREMENT AND PAYMENT—Square Yard of deck area regardless of the number of passes.