511PREPARATION FOR CONCRETE

New Hampshire Department of Transportation Standard Specifications – 2016 BRIDGE DECK REPAIRS Description

1.1This work shall consist of the preparation for repairs of concrete bridge deck including the removal of bituminous materials,

the removal of unsound concrete from the existing deck to assure proper repair, and the disposal of all materials removed. Equipment

2.1The equipment used for pavement and concrete removal shall be subject to approval of the Engineer and shall comply with

the following: 2.1.1 Bituminous pavement removal. 2.1.1.1 The pavement removal may be performed with planers, backhoes, loaders, or other approved mechanical equipment. 2.1.2 Bridge deck concrete overlay. 2.1.2.1 Scarifying equipment shall be either a power operated rotary scarifier or a high-pressure waterjet scarifier capable of uniformly scarifying the existing surface to the depth required i n a satisfactory manner. Scarifying equipment shall be fully automated. Power operated rotary scarifier shall be equipped with a short ski, shoe or a similar device attached to the cutter head to limit the depth of cut. The use of multiple impact or vibratory equipment will not be allowed. 2.1.2.2 Sand or water blasting equipment shall be capable of removing rust and loose concrete from the exposed reinforcement and concrete surface. 2.1.3 Bridge deck concrete partial or full depth repairs. 2.1.3.1 Sawing equipment shall be capable of cutting concrete to the specified depth. 2.1.3.2 Power driven hand tools for concrete removal will be permitted with the following restrictions:

the surface of the deck.

reinforcing bar.

achieve the required depth of removal. 2.1.3.3 High-pressure waterjet equipment, either hand held or remote controlled, will be permitted for concrete removal. Construction Requirements

3.1Concrete and pavement shall be removed from each area as shown on the plans or required. Removal areas as shown are

based on Department studies; actual removal areas will be determined by the Engineer. The various classes of removal shall be accomplished according to the following requirements. 3.1.1 When preparation for bridge deck concrete overlay is not specified, the concrete bridge deck pavement removal shall be accomplished with equipment capable of removing the existing bituminous pavement and membrane waterproofing without damaging the top surface of the deck concrete. The preparation of the deck surface prior to placement of new barrier membran e shall include removal of all existing membrane waterproofing and any membrane primer which is not tightly adhered to sound concrete. The Engineer may order sand blasting of a test area of primer to determine its acceptability for leaving in place. Additional preparation of the deck surface shall be as recommended by the manufacturer of the new barrier membrane to be applied. 3.1.2 When preparation for bridge deck concrete overlay is specified, the entire existing concrete deck area shall be uniformly scarified to a minimum depth of 1/4” or as specified on the plans. Removal to a greater depth will be required adjacent to scuppers and expansion joints and elsewhere, as shown on the plans or ordered. All full and partial depth repairs shall be performed prior to the scarification of the entire deck, unless otherwise permitted. 3.1.3 When removal for partial or full depth repairs is specified, the concrete may be removed by chipping or by a combination of scarifying and chipping, except that final chipping, in any case, shall be by use of hand tools. The entire periphery of the partial or full depth removal areas shall be saw cut to a minimum depth of 1”. or to the top of the upper reinforcing steel. Care shall be taken to avoid cutting into any reinforcing bars. Care shall be exercised to prevent stretching or damaging exposed reinforcing steel. 3.1.3.1 Partial depth removal for all concrete within the periphery of the designated removal area shall extend at least to 3/4” below the lower bars of the top reinforcing steel mat, or deeper as required to r emove all unsound concrete. The Engineer may

New Hampshire Department of Transportation Standard Specifications – 2016 require enlargement of a designated partial removal area should inspection reveal deterioration of concrete or corrosion of t he reinforcing beyond the limits originally designated. In designated areas of partial depth removal where less than one half the designed deck thickness remains, all concrete shall be removed. Designated partial depth removal areas which become full dep th removal shall be treated as full depth removal areas in accordance with 3.1.3.2. Limited areas of partial depth removal greater than half the slab thickness (such as beneath reinforcing) may be allowed by the Engineer. These limited areas of excess partial depth will be treated as partial depth removal. 3.1.3.2 Full depth removal shall consist of removing all concrete for the full depth of the bridge deck. The lateral limits of this removal shall be to sound existing concrete, as determined by the Engineer. Areas where unsound concrete exists on the bottom surface of the deck shall b e repaired by full depth removal even if the concrete directly above the unsound concrete is sound. 3.1.3.2.1 Full depth concrete removal on those portions of the bridge deck over roadways, railroads or waterways shall be accomplished with the least possible disruption of the normal traffic flow under the deck. Special care and precautions, including protective structures as required or ordered, shall be taken to ensure that no debris is allowed to fall on any roadway, rail road, or waterway. All preparation work shall be carried out so as to prevent damage to those portions of the bridge that are to remain.

3.2The thickness of any new concrete above the prepared surface or reinforcing steel shall be at least 3/4 ” and may be greater

as shown on the plans. This clearance shall be checked according to the following: 3.2.1 A filler block having a thickness of 1/8” less than the required concrete thickness shall be attached to the bottom of the screed or an approved template, which shall then be passed over th e area to be concreted. All old concrete which does not have sufficient clearance shall be removed. All reinforcing steel which does not have sufficient clearance shall be depressed. It may be necessary to remove concrete beneath some reinforcement to permit depressing the reinforcement adequately. Hand tools shall be used to remove final portions of concrete to achieve the required depth.

3.3Any slurry produced by wet sawing shall be thoroughly flushed from the concrete surface by a jet of water, and puddles of

water shall be removed with an oil-free air blast before the start of any patching or overlay operations.

3.4All surfaces of existing concrete including any previously placed concrete to be in contact with the new concrete shall be

thoroughly cleaned by sandblasting or high-pressure water-blasting.

3.5Reinforcing steel or other steel to be in contact with the new concrete shall be cleaned of all grease, dirt, concrete mortar

and injurious rust. Injurious rust shall be interpreted to mean rust which is not firmly bonded to the steel. Rust which is difficult to remove by vigorous scrubbing with a wire brush shall be considered firmly bonded to the steel.

3.6Any portions of granite curb and mortar against which new concrete is to be placed shal l be blast cleaned. Loose granite

curb shall be reset in accordance with Section 609. Any deteriorated curb mortar bed shall be removed and replaced.

3.7After sandblasting or water-blasting and just prior to applying the bonding agent or grout in preparation for placement of the

new concrete, all surfaces which will be in co ntact with new concrete shall be vacuum -cleaned or air -blown. A combination of vacuum cleaning and air-blowing may be required.

3.8After the bridge deck has undergone removal of old concrete and before new concrete has been placed and cured, construction

loads shall not be permitted which exceed either an 8,000 lb. wheel load or a 16,000 lb . axle load. Any combination of axles spaced closer than 4 ft. center-to-center shall be considered as one axle. Placement of construction loads on the removal area shall be subject to approval of the Engineer. Method of Measurement

4.1Concrete bridge deck pavement removal and preparation for concrete bridge deck overlay will not be measured, but shall be

the square yard final pay quantity in accordance with 109.11 for the area within the limits shown on the plans.

4.2Preparation for partial depth concrete bridge deck repairs and preparation for full depth concrete bridge deck repairs will be

measured by the square yard to the nearest 0.1 of a square yard. 4.2.1 Preparation for partial depth concrete bridge deck repairs and preparation for full depth concrete bridge deck repairs may be measured within the same areas as preparation for concrete bridge deck overlay with no reduction in the pay quantity o f Item 511.01. 4.2.2 Partial depth removal areas which become full depth removal areas will be measured as Item 511.03.

New Hampshire Department of Transportation Standard Specifications – 2016 Basis of Payment

5.1Concrete bridge deck pavement removal and preparation for concrete bridge deck overlay are final pay quantity items and

will be paid for at the Contract unit price per square yard in accordance with 109.11 . 5.1.1 The removal of bituminous materials on the roadway approaches will be paid for under Section 417. 5.1.2 Protective structures if required will be subsidiary to Item 511.03.

Pay items and units:

511.00Concrete Bridge Deck Pavement Removal (F) Square Yard

511.01Preparation for Concrete Bridge Deck Overlay (F) Square Yard

511.02Preparation for Partial Depth Concrete Bridge Deck Repairs Square Yard

511.03Preparation for Full Depth Concrete Bridge Deck Repairs Square Yard

New Hampshire Department of Transportation Standard Specifications – 2016

Description

This work shall consist of inspecting and preparing existing deteriorated concrete surfaces for rep airs at the locations shown

on the plans and as directed by the Engineer. Since a significant portion of the work may involve discovering and repairing hidden deteriorated concrete, the Contractor should carefully inspect the work area before bidding. Construction Requirements

Scaffolds shall be furnished and erected at those locations where necessary to perform inspection, preparation and repair

work.

Cleaning the concrete in preparation for the repairs shall include the following work as required and directed:

3.2.1 Visually examining and testing the concrete surface by sounding with a hammer to detect hidden deterioration which is indicated by a hollow sound when struck. While work is in progress, the Contractor and Engineer shall jointly inspect and sound the concrete areas to be repaired to determine the limits of the work. 3.2.2 Removing deteriorated concrete to a sound concrete surface free of laitance, dirt, or other foreign material shall be done by power brushing, the use of jackhammers where their use is allowed, sawing, sandblasting, water blasting, mechanical abrading, hosing with water, air -blast cleaning, or other approved methods. If reinforcing steel is exposed when removing concrete to a sound surface, or if exposure of the reinfor cing steel in prepared areas is required by the plans, the minimum depth of removal shall be 1-1/2” behind the main reinforcing steel. If reinforcing steel is not exposed when removing concrete to a sound surface, and if exposure of the reinforcing steel in prepared areas is not required by the plans, the minimum depth of removal shall be 1/2” plus the maximum coarse aggregate size of the patching material. 3.2.3 The edges of all prepared areas shall be saw cut to a minimum depth of 1/2 ” plus the maximum coarse aggregate size of the patching material. On vertical surfaces, if forms are to be used, the shape of the areas to be patched shall be such that the entire area to be patched is easily accessible, as determined by the Engineer. Although an occasional distribution or tie reinforcing bar may be cut, main reinforcing steel shall not be saw cut except as shown on the plans. 3.2.4 Reinforcing steel or other steel to be in contact with the new concrete shall be cleaned of all grease, dirt, concrete mortar and injurious rust. Injurious rust shall be interpreted to mean rust which is not firmly bonded to the steel. Rust which is difficult to remove by vigorous scrubbing with a wire brush shall be considered firmly bonded to the steel. Method of Measurement

Preparation for concrete repairs will be measured by the square yard to the nearest 0.1 of a square yard as determined by

actual surface measurements of the lengths and widths of all the surfaces prepared.

Areas prepared to a sound surface without exposing reinforcing steel will be measured as Class I preparation areas. Areas

prepared to a sound surface a minimum of 1-1/2” behind the reinforcing steel will be measured as Class II preparation areas. Basis of Payment

The accepted quantity of preparation for concrete repairs will be paid for at the Contract unit price per square yard complete.

Pay items and units:

512.01Preparation for Concrete Repairs, Class I Square Yard

512.02Preparation for Concrete Repairs, Class II Square Yard