515Removal of Bridge Deck Concrete

Removal of Bridge Deck Concrete

515.1DESCRIPTION

1 This section describes the requirements for scarifying, hydro-demolition, and removing unsound and delaminated areas of concrete.

515.2MATERIALS--Vacant

515.3EQUIPMENT

515.3.1 Surface Preparation Equipment for Class I-A, Class I-B, Class II-A and Class II-B

1 Provide sawing, mechanical scarifying, sandblasting equipment, and all other tools necessary to complete the work.

2 Provide power-driven hand t ools to r emove unsound concrete. W ith the e ngineer’s approval, jackhammers heavier than the nominal 30-pound [14 kg] class or 60-pound [27 kg] hammers with a spade at least 6 in [150 mm] wide may be used.

3 Provide self-propelled mechanical scarifying equipment capable of accurately establishing profile grades by referencing from the existing deck or from an independent grade control. Ensure that the equipment has the following:

depth of cut; and

515.3.2 Surface Preparation Equipment for Hydro-Demolition

1 Provide hydro-demolition equipment that is a computerized, self-propelled machine that utilizes a high pressure water jet stream. Ensure the hydro- demolition equipment is capable of removing the depth of concrete shown in the contract, and specified unsound concrete. Provide vacuum cleanup equipment that is capable of removing wet debris and water.

agent to observe the initial set-up of the equipment and to assure that the removal operation is progressing to the satisfaction of the engineer. Ensure the agent has proven experience with hydro-demolition removal operations. Ensure the agent is

Removal of Bridge Deck Concrete SECTION 515

on-site observing the hydro- demolition operation until proper procedures have been established, or a minimum of 24 working hours.

2 Provide shielding to ensure containment of all dislodged material and to prevent flying debris adjacent to and under the work site. Ensure the vacuum system immediately removes water and debris from the bridge deck. Do not allow excess water to dry on the existing concrete surface. Ensure all water runoff and residual material is contained and collected within the existing roadway.

515.4CONSTRUCTION

515.4.1 General

1 The department classifies bridge deck repair as follows:

disposing of removed concrete. Depth is classified as follows:

1.1Class I-A: ¼ in [5 mm]

1.2Class I-B: greater than ¼ in [5 mm] to 2 ½ in [70 mm]

and disposing of removed concrete. Depth is classified as follows:

2.1Class II-A: up to one-half total slab thickness.

2.2Class II-B: from one-half to total slab thickness.

unsound concrete up to one-half total slab thickness.

515.4.2 Surface Preparation – Class I-A, Class I-B, Class II-A and Class II-B

1 Where specified or designated by the engineer, remove unsound concrete from the bridge deck. Remove existing maintenance patches to original repair depth or deeper, as required to remove unsound concrete. Do not operate jackhammers or mechanical chipping tools at an angle in excess of 45 degrees, measured from the slab surface. Use hand tools to remove final particles of unsound concrete or achieve the required depth. Work so that saw slurry drains from, and stays away from, areas cleared of unsound concrete.

2 When placing new concrete, keep at least ¾ in [19 mm] of clear distance around these bars. Secure loose reinforcing steel.

Removal of Bridge Deck Concrete SECTION 515

3 Avoid cutting, stretching or damaging existing reinforcing steel. Remove and replace damaged reinforcing steel with the same size bar using splices in accordance with Subsection 514.4.5.2, Reinforcing Steel Splices, at no additional cost to the department. In the weld or damaged areas, sandblast and repair coated reinforcing steel in accordance with Subsection 514.4.1.1, Coated Reinforcing Steel, at no additional cost to the department.

4 Specific repair requirements are as follows:

class I-A or I-B repair or prepare to the depth specified. Do not remove more than 1 ¼ in [30 mm] in one pass.

Make a test pass from 20 ft [6 m] to 40 ft [12 m] in length with the scarifying machine. After the pass, the engineer will inspect the deck. If microcracks from scarifying are present, stop scarification and correct the problem before continuing.

The top mat of reinforcing steel may be exposed or near the surface of the deck; do not damage this steel.

Ensure that the resulting deck surface is free of excessive scarification marks and other damage. Correct surface irregularities greater than ¼ in [6 mm] above or below specified grade. Perform any additional scarifying required to correct irregularities, at no additional cost to the department.

designated for class II-A repair approximately ¾ in [19 mm] deep or to the top of reinforcing bars if the bar depth is less. Cut along repair boundaries, except those next to a curb face. Make this cut initially or after removing sufficient concrete to reasonably establish the limits of the removal area.

Remove loose and unsound material. Where at least half the circumference of a reinforcing bar is exposed or where concrete and steel are no longer bonded, remove the concrete to clear at least ¾ in [19 mm] around the bar. Do not use chipping hammers heavier than the nominal 15-pound [7 kg] class to remove concrete below reinforcing bars.

T he engineer may enlarge a designated removal area if concrete is deteriorated beyond previously designated limits. Saw-cut around the enlar ged area with a “dry” blade before beginning removal.

the repair a class II-B in areas of class II-A repair where the depth of remaining sound concrete is less than 50 percent of the original deck depth. Remove concrete in these areas by chipping and using hand tools. Perform final removal

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at the edges of class II-B repair areas with 15-pound [7 kg] chipping hammers or hand tools.

Provide forms for placing new concrete in the full-depth opening. Suspend forms from existing reinforcing bars by wire ties, or for large openings, support forms by blocking from beam flanges. In all cases, support forms using elements of the existing superstructure.

5 Clean all repair areas by sandblasting. Clean exposed reinforcement of rust and clinging concrete and existing concrete against which new concrete will be placed.

515.4.5 Surface Preparation – Hydro-Demolition

With the engineer present, calibrate the hydro-demolition equipment prior to performing concrete removal operations. Use a test section of sound concrete, as designated by the engineer. Adjust the equipment settings until the depth of concrete shown in the contract is removed, and the exposed bridge deck exhibits a highly rough and bondable surface. Utilize a second test section of unsound concrete, as designated by the engineer. Adjust equipment settings to remove all unsound concrete up to one- half the original deck thickness.

Verify the removal depth every 15 ft [4572 mm]. Record the equipment settings throughout the concrete removal operations. Adjust settings, if necessary. The top mat of reinforcing steel may be exposed or near the surface of the original deck surface. Do not damage steel.

Do not allow excess water or material to flow into adjacent travel lanes open to traffic or below the structure. Dispose of the excess water and debris.

After the hydro-demolition operation is performed, the engineer wil l inspect the bridge deck and delineate additional areas requiring repair. In the designated areas, remove loose and unsound material. The removal of sound concrete under exposed reinforci ng steel is not necessary. Do not use chipping hammers heavier than the nominal 15 lb class to remove concrete below reinforcing bars. A hand held hydro-wand may be used in lieu of power driven hand tools or jackhammers. The engineer may enlarge a designated removal area if concrete is deteriorated beyond previously designated limits.

515.4.5.1 Personnel

1 Provide the engineer with documentation that the hydro- demolition equipment is operated by qualified personnel trained by the manufacturer of the equipment.

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515.5MEASUREMENT and PAYMENT

515.5.1 General

1 The engineer will measure:

Class II-A, and Bridge Deck Repair Class II-B by the square yard [square meter].

The engineer will measure Bridge Deck Repair Class I-A and Bridge Deck Repair Class I-B for all areas scarified, including the area of Class II repairs. Areas measured as Bridge Deck Repair Class I-B will not be included in the measured quantity of Bridge Deck Repair Class I-A. Areas measured as Bridge Deck Repair Class II-B will not be included in the measured quantity of Bridge Deck Repair Class II-A.

When additional removal for relatively high areas is specified by the engineer for Bridge Deck Repair Class I -A, or when the required removal depth for Bridge Deck Repair Class I-B exceeds 1 ¼ in [30 mm], the engineer will measure for payment a second time.

Additional repair up to one -half the original deck thickness will not be measured for payment and is incidental to the hydro-demolition.

2 The department will pay as follows:

Pay Item

Pay Unit Measure to the Nearest Pay to the Nearest Bridge Deck Repair Class I-A SY [m2] 0.1 ft [0.05 m] SY [m2] Bridge Deck Repair Class I-B SY [m2] 0.1 ft [0.05 m] SY [m2] Bridge Deck Repair Class II-A SY [m2] 0.1 ft [0.05 m] SY [m2] Bridge Deck Repair Class II-B SY [m2] 0.1 ft [0.05 m] SY [m2] Bridge Deck Repair, Hydro-Demolition SY [m2] 0.1 ft [0.05 m] SY [m2]

515.5.2 Referenced Sections for Direct Payment

1 When specified, the engineer will measure and pay for water in accordance with Section 209, Watering.