704Concrete Masonry Repair

704.1 Description. This work shall consist of removing deteriorated concrete, preparing the repair site, forming

where required, placing and finishing new concrete or qualified special mortar, applying epoxy and applying concrete crack filler in the required areas.

704.2 Material. All material shall be in accordance with Division 1000, Material Details, and specifically as

follows. The qualified special mortar shall be from the qualified rapid set concrete patching material listing available from Construction and Materials or MoDOT’s web site. Item Section Concrete 501 Concrete Bonding Compound and Epoxy Mortar 623 Gradation E Coarse Aggregate 1005 Type III Cement 1019 Type III Epoxy or Epoxy Material for the Polymer Wearing Surface 1039 Concrete Crack Filler 1053 Water 1070

704.3 Types of Repair.

704.3.1 Half-Sole Repair. This work shall consist of partial removal and replacement of bridge deck concrete in

the required areas. Repair areas shall consist of deck imperfections exposing the upper layer of the top mat of reinforcing steel a 1/4 inch. Slight deck imperfections less than 1/2 inch will not be repaired for bridge decks to be covered with an asphalt or concrete wearing surface. Slight deck imperfections less than 1/4 inch will not be repaired for bridge decks to be covered with a seal coat, polymer type wearing surface or no wearing surface.

704.3.2 Deck Repair With Void Tube Replacement. This work shall consist of partial removal and

replacement of bridge deck concrete and removal and replacement of the deteriorated void tube in the required areas.

704.3.3 Full Depth Repair. This work shall consist of complete removal and replacement of the bridge deck

concrete in the required areas and for voided slabs, the removal and replacement of the deteriorated void tube in the required areas.

704.3.4 Modified Deck Repair. This work shall consist of the removal of visibly loose or spalled bridge deck

concrete and placement of Class B-1 concrete or qualified special mortar in the areas where the reinforcing steel is exposed. If reinforcing steel is not exposed, the asphalt wearing surface in accordance with Sec 403 shall be placed monolithically into the deck imperfections.

704.3.5 Superstructure Repair (Unformed). This work shall consist of repairing the deteriorated concrete on

the bottom of the bridge deck in the required areas with a qualified special mortar.

704.3.6 Slab Edge Repair. This work shall consist of repairing the edge of the bridge deck by removing

deteriorated concrete and patching the required areas with a qualified special mortar. All repairs made within 4 inches of the edge of the bridge deck, regardless of the repair thickness, will be considered slab edge repair. Portions of the bridge deck areas requiring repair that extend more than 4 inches from the edge of the bridge deck shall be repaired as superstructure repair (unformed) or full depth repair.

704.3.7 Substructure Repair (Formed). This work shall consist of formed substructure repair. The required

areas shall be patched with Class B-1 concrete. Coarse aggregate shall be Gradation E in accordance with Sec 1005. The extent of a single formed repair area for measurement shall be the contiguous concrete surfaces that meet at a formed edge.

704.3.8 Substructure Repair (Unformed). This work shall consist of unformed substructure repair. The

required areas shall be patched with a qualified special mortar.

704.3.9 Epoxy Sealing. This work shall consist of applying an epoxy material to the concrete in the required

areas.

704.3.10 Concrete Crack Filler. This work shall consist of applying a concrete crack filler to the concrete in

the required areas.

704.3.11 Monolithic Deck Repair. This work shall consist of providing and placing supplementary wearing

surface material necessary to fill all depressions in the deck below the bottom of the planned deck wearing surface thickness. This material is placed monolithic during the deck wearing surface process.

704.3.12 Shallow Deck Repair. This work shall consist of removal of bridge deck concrete in required areas

and placing polymer concrete per Sec 623.40. Repair areas shall consist of deck imperfections deeper than 1/4 inch to a depth where reinforcing steel is not exposed. Slight deck imperfections less than 1/4 inch will not be repaired.

704.3.13 Cleaning and Epoxy Coating. In order to protect the bridge superstructure concrete from deicing

chemicals and other contaminants, all loose and delaminated concrete shall be removed, and a protective epoxy coating shall be applied to the concrete in the area of curb outlets and the vertical face of the curbs as shown in the bridge plans.

704.3.13 1 Construction Requirements. The areas to be cleaned and epoxy coated shall be as follows:

704.3.13 1.2 Cleaning shall include removal of all loose and delaminated concrete with hand tools to the

satisfaction of the engineer. Hand tools may include chipping chisels, wire brushes, dust brushes, etc. After cleaning, an epoxy coating meeting the requirements of Sec 1059.20 shall be applied in accordance with Sec

711.3.2 and the manufacturer’s recommendations.

704.4 Construction Requirements for Non-Hydro Demolition Projects.

704.4.1 Removal Requirements.

704.4.1 1 General. The type of repair and areas to be repaired will be outlined by the engineer. Determination of

deck repair areas will be by sounding, except when modified deck repair is specified. All loose, deteriorated and unsound concrete in the required repair areas shall be removed by conventional hand/mechanical or other approved equipment

704.4.1 2 Conventional Hand/Mechanical Equipment. For bridge decks rated 6 or above, conventional

hand/mechanical equipment consisting of jackhammers no heavier than the 35-pound class shall be used for concrete removal, except that for modified deck repair chip hammers no heavier than 15-pound class shall be used. For bridge decks rated 5 or below, the jackhammers shall not be heavier than the 65-pound class, except for modified deck repair. Chipping hammers from the 15-pound class shall be used to remove concrete from beneath any reinforcing bars, where required. The bits shall be sharp in order to reduce pounding. Jackhammers shall be operated to minimize damage to the sound concrete around the patch area. Other methods that would be less damaging to the concrete and reinforcement may be used with approval from the engineer.

704.4.1 3 Concrete Removal. A boundary perimeter with one-inch vertical sides shall be established outside the

deteriorated area. The deteriorated concrete shall be removed as required to provide good sound concrete on which new concrete can be placed and satisfactorily bonded to the reinforcing bars. The areas of repair shall be made approximately rectangular with the sides generally perpendicular to the surface being repaired. These areas shall be carefully removed such that reinforcement is not disturbed or damaged. For full depth repair, a saw cut outside the deteriorated area shall also be made on the bottom of the bridge deck, except on voided slab, solid slab and box girder bridges without entry access. Other acceptable methods for saw cutting the bottom of the deck may be used with approval from the engineer. No more than one-fourth of the column perimeter shall be removed at any one time, and no more than one-eighth of the column perimeter if the repair is completed under live load. Once the one-quarter or one-eighth limit has been reached, the column shall be repaired before any further column removal is done.

704.4.1 4 Reinforcing Bar Exposed. All exposed reinforcing bars shall be thoroughly cleaned by sand, shot or

water blasting to the satisfaction of the engineer.

704.4.1 4.1 The concrete within the boundary area for superstructure repair (unformed), substructure repair

(formed) and substructure repair (unformed) shall be removed a minimum of one inch beyond the inside edge of any exposed reinforcing bars, including the main reinforcement.

704.4.1 4.2 When the bond between existing concrete and a reinforcing bar has been destroyed, or more than

half the diameter of a reinforcing bar is exposed during half-sole and modified deck repair, the concrete adjacent to the reinforcing bar shall be removed to a depth that will permit the concrete to bond to the entire periphery of the bar. A minimum of one-inch clearance shall be maintained.

704.4.1 4.3 If a reinforcing bar is exposed during slab edge repair, the concrete adjacent to the bar shall be

removed to a depth that will permit a qualified special mortar to bond to the entire periphery of the bar. A minimum of one-inch clearance shall be maintained.

704.4.1 5 Reinforcement Repair. Particular care shall be taken not to disturb or damage reinforcing bars. All

exposed reinforcing bars shall be thoroughly cleaned by sand, shot or water blasting. Cut or broken bars or bars with 25 percent or more cross sectional area lost shall be spliced 24 diameters on each side of the damage with new bars of the same size in accordance with Sec 706. Damaged existing epoxy coated reinforcement shall be repaired in accordance with Sec 710.

704.4.1 6 Material Disposal. All material removed shall be disposed of in accordance with Sec 202.

704.4.2 Preparation of the Repair Area.

704.4.2 1 Concrete Repair. After removal of deteriorated concrete, the area to be repaired shall be sand, shot or

water blasted to remove all foreign matter, dirt, free standing water and loose material and micro-cracking. Clean-up and disposal of blast material shall be in accordance with Sec 202.3.1.3. The area to come in contact with new concrete shall be cleaned as stated above, saturated with water and painted with a concrete bonding compound or an epoxy mortar prior to placing new concrete. A concrete bonding compound shall be used for all structures with the following exception. An epoxy mortar shall be used on box girder, voided and solid slab structures and on structures where a cathodic protection system is to be installed.

704.4.2 2 Epoxy Sealing. The area to be sealed shall be cleaned by sand or shot blasting. Clean-up and disposal

of blast material shall be in accordance with Sec 202.3.1.3. Prior to sealing the concrete, all loose particles and foreign matter shall be removed using oil-free and water-free compressed air or a vacuum of at least 90 psi.

704.4.2 3 Concrete Crack Filler. The area to fill the cracks shall be cleaned by pressure washing with at least

2500 psi, 3 days minimum prior to the crack filler application and 2 days after any measurable precipitation.

704.4.3 Placement of Repair Material.

704.4.3 1 Concrete Repair. Concrete shall be placed before the concrete bonding compound or epoxy mortar

has begun to set. Deck repair concrete shall be placed in the repair area to match the top of the original deck surface. For bridges to be covered with concrete wearing surface, deck repair concrete shall be placed in the repair area up to the bottom of the proposed concrete wearing surface. The finished repair area shall have a light broom texture for bonding of the deck seal, except bridges to be covered with concrete wearing surface shall have a rough surface for bonding of the concrete wearing surface. All joints shall be formed to match any existing joint pattern

704.4.3 1.1 Concrete for concrete deck repair shall be Class B-2 except as specified in Sec 704.3.4 and Sec

704.4.3 1.2 and that solid slab, voided slab and box girder structures shall be the same class as the existing deck

concrete. The repair area shall not be opened to any traffic until the concrete has reached a compressive strength of 3200 psi. Type III cement may be used to accelerate the set. The coarse aggregate shall be Gradation E in accordance with Sec 1005. Accelerating additives containing chlorides will not be permitted.

704.4.3 1.2 Concrete for repairing bridge decks with cathodic protection systems shall be Class B-1. The repair

area shall not be opened to any traffic until the concrete has reached a compressive strength of 3200 psi. Type III cement may be used to accelerate the set. The coarse aggregate shall be Gradation E in accordance with Sec 1005. Accelerating additives containing chlorides will not be permitted. All half-sole repairs made on the deck shall be Class B-1 concrete that has a maximum chloride ion content of 5 pounds per cubic yard. All full depth repairs made on the deck shall be chloride-free Class B-1 concrete from the bottom of the deck to within one inch of the lowest rebar of the top layer of reinforcing steel. The remainder of the repair shall be Class B-1 concrete with a maximum chloride ion content of 5 pounds per cubic yard.

704.4.3 1.3 The repaired areas shall be cured in accordance with Sec 703.

704.4.3 2 Epoxy Sealing. The area to be sealed shall be sealed with a qualified Type III epoxy or epoxy material

for the polymer wearing surface. Sealing shall be completed before the application of any wearing surface. The cleaning, sealing and epoxy application shall proceed only as approved by the engineer, in accordance with the manufacturer’s written recommendations. The epoxy application and rate of coverage shall be in accordance with manufacturer’s recommendations, with a maximum coverage of 100 square feet per gallon.

704.4.3 3 Concrete Crack Filler. The area to fill the cracks shall be filled with a low viscosity polymer crack

filler. The concrete crack filler application and rate of coverage shall be in accordance with the manufacturer’s recommendations, with a maximum coverage of 100 square feet per gallon. The broadcasting of dry blasting sand shall be applied only as approved by the engineer, in accordance with the manufacturer’s written recommendations with a maximum coverage of 1 to 2 pounds per square yard starting approximately 10 minutes after crack filling operation has started.

704.5 Construction Requirements for Hydro Demolition Projects.

704.5.1 Zoned Conventional Deck Repair Prior to Hydro Demolition.

704.5.1 1 Prior to hydro demolition, the deck shall be repaired inside special repair zones as called for in the

contract plans in accordance with Sec 704.4 except as follows:

704.5.2 Conventional Half-Sole Repair After Hydro Demolition.

704.5.2 1 For polyester polymer concrete or low slump concrete wearing surfaces, following removal of

unsound original concrete by hydro demolition and hand chipping, any areas requiring half-sole deck repair will be identified by the engineer.

704.5.2 2 All half-sole repair identified by the engineer shall be made prior to the deck wearing surface.

704.5.2 3 Half-sole repair shall be in accordance with Sec 704.4 except that the removal is accomplished by

hydro demolition and limited only to locations where the removal of concrete around the perimeter of the top transverse reinforcing steel is required.

704.5.2 4 Concrete or qualified repair mortars used for half-sole repair shall be fully cured prior to placing the

wearing surface.

704.5.3 Conventional Full Depth Repair After Hydro Demolition.

704.5.3 1 Following removal of unsound original concrete by hydro demolition and hand chipping, any areas

requiring a full depth repair will be identified by the engineer.

704.5.3 2 For polyester polymer concrete or low slump concrete wearing surfaces on all bridge decks and all

concrete wearing surfaces on voided slab bridges, all full depth repair shall be made prior to the deck wearing surface in accordance with Sec 704.4 except that the removal is accomplished by hydro demolition.

704.5.3 3 For concrete wearing surfaces not covered by Sec 704.5.3.2, full depth repair for areas greater than 5

square feet (3 square feet in areas of presstressed panels) shall be made prior to the deck wearing surface in accordance with Sec 704.4 except that the removal is accomplished by hydro demolition and concrete may be placed in the repair area up to one inch below the top mat of reinforcement.

704.5.3 4 If the engineer determines that for concrete wearing surfaces not covered by Sec 704.5.3.2, full depth

repair for areas less than or equal to 5 square feet (3 square feet in areas of presstressed panels) can be made monolithic with the new deck wearing surface. The contractor shall form the bottom of the repair prior to the wearing surface. No payment will be made for forming the bottom of full depth monolithic repairs, including form removal.

704.5.3 5 Concrete or qualified repair mortars used for full depth repair shall be fully cured prior to placing the

wearing surface.

704.5.4 Void Tube Replacement Requiring Conventional Deck Repair After Hydro Demolition.

704.5.4 1 Following removal of unsound original concrete by hydro demolition and hand chipping, any void

tubes requiring replacement will be identified by the engineer.

704.5.4 2 Deck repair required for void tube replacement shall be in accordance with Sec 704, except that the

removal is accomplished by hydro demolition.

704.5.4 3 Concrete or qualified repair mortars used for deck repair with void tube replacement shall be fully

cured prior to placing the wearing surface.

704.5.5 Monolithic Deck Repair After Hydro Demolition.

704.5.5 1 Monolithic deck repair shall not be used with void tube replacement and with polyester polymer or

low slump concrete when more than half the diameter of the top bar is exposed.

704.5.5 2 For deck repair and concrete wearing surfaces not covered by Sec 704.5.5.1, shallow and deep areas,

including approved full depth repair areas, shall be filled monolithically with the deck wearing surface. Removal of concrete around the perimeter of the bar, as specified in Sec 704.4.1.4.2 is not required for areas where the bond between existing concrete and reinforcing steel has not been compromised, as determined by the engineer. Partially exposed reinforcing steel that is bonded to the deck concrete is acceptable.

704.6 Method of Measurement. Final measurement will not be made for preparation of the existing deck. No

duplication of measurement will be made for full depth repair, half-sole repair, deck repair with void tube replacement, monolithic deck repair, shallow deck repair, slab edge repair, superstructure repair (unformed) or modified deck repair. No duplication of measurement will be made for substructure repair, unformed and formed.

704.6.1 Half-sole repair, deck repair with void tube replacement, shallow deck repair, full depth repair, modified

deck repair, superstructure repair (unformed) and substructure repair (formed and unformed) will be measured to the nearest square foot.

704.6.2 Slab edge repair will be measured to the nearest linear foot.

704.6.3 No measurement will be made for epoxy sealing.

704.6.4 Measurement of reinforcing steel replaced due to excess section loss will be made to the nearest 10

pounds.

704.6.5 Filling concrete cracks will be measured to the nearest square foot.

704.6.6 Supplementary wearing surface material required to fill monolithic deck repair will be measured in

accordance with Sec 505.

704.6.7 No measurement will be made for Cleaning and Epoxy Coating except for authorized changes during

construction or where appreciable errors are found in the plan quantity. When required, measurement will be made to the nearest square foot.

704.7 Basis of Payment. Accepted quantities of concrete masonry repairs will be paid for at the contract unit

price for each of the pay items included in the contract, except for the following repairs.

704.7.1 Supplementary wearing surface material required to fill monolithic deck repair will be paid for in

accordance with Sec 505.

704.7.2 No direct payment will be made for epoxy sealing.

704.7.3 Payment for accepted quantities of reinforcing steel replaced due to excess section loss will be paid for

at the fixed contract unit price specified in Sec 109.16. No payment will be made for replacement of reinforcing steel cut or broken by the contractor.