SECTION 533: CONCRETE STRUCTURE REPAIR
533.1 Description
This Work consists of the following: 1. Establishing repair areas; 2. Removing loose, unsound, and deteriorated concrete; 3. Preparing and cleaning concrete surfaces; 4. Removing and replacing or suppl ementing compromised reinforc ing bars; and 5. Furnishing, placing, finishi ng, and curing concrete repair M aterials.
533.2 Materials
533.2.1 Concrete Repair Material (referred to as “Concrete” or “Repair Material”)
The Contractor shall use enriched mortar where the repair depth is less than one (1) inch, and use enriched concrete where the repair depth is one (1) inc h or greater, unless otherwise directed by the manufacturer. If the repair depth is four (4) inches or greater, the Contractor shall use enriched concrete or the appropriate class concrete p er Section 509, “Portland Cement Concrete Mix Designs.” C oncrete repair Material may opt ionally be pre-packaged rapid-hardening cementitious Materials or two (2)-part epoxy an d aggregate repair Material. When using enriched mortar, enr iched concrete, or rapid-hardeni ng cementitious Material, the Contractor may use concrete mixtures developed an d approved in accordance with Section 509, “Portland Cement Concrete Mix Designs” or pre -packaged, pre-blended cementitious Materials in accordance with this Section, that ar e combined with water at the site. Manufacturer’s certified strength tests shall be Accepted inste ad of tests by the State Materials Bureau. Testing may be performed by the State Materi als Bureau at any time. Tests by the State Materials Bureau shall supersede manufacture r’s certified tests.
533.2.1 1 Enriched Mortar
Table 533.2.1.1:1 Enriched Mortar Physical Property Requirements Property ASTM Test Requirements Compressive strength, minimum C-109 One (1) Day: 2,700 psi Seven (7) Days: 3,200 psi 28 Days: 4,500 psi Bond strength, minimum C-882 One (1) Day: 1,000 psi Seven (7) Days: 2,000 psi 28 Days: 3,000 psi Linear length change, Maximum C-157 28 Days wet: +0.05 %a 28 Days dry: -0.05 % Coefficient of thermal expansion (in/in/°F) C-531 3.9 x 10-6 to 7.1 x 10-6 Enriched Mortar Physical Property Requirements Freeze/thaw resistance @ 300 cycles, minimum C-666 Per Section 509.2.8.4.2, Note 3 aThe maximum allowable expansion is 0.4% if the locations where enriched mortar is used can tolerate such expansions without exceeding the elastic limit. The Contractor shall provide enr iched mortar that consists of a blended patching Material and water. The Contractor shall provide enriched mortar with p hysical properties in accordance with Table 533.2.1.1:1, “Enriched Mortar Physical Pr operty Requirements.”
533.2.1 2 Enriched Concrete
The Contractor shall provide enr iched concrete consisting of en riched mortar extended with recommended amounts of coarse aggregate. The Contractor s hall provide enriched concrete with physical properties in accordance with Table 533. 2.1.2:1, “Enriched Concrete Physical Property Requirements.” Table 533.2.1.2:1 Enriched Concrete Physical Property Requirements Property ASTM Test Requirements Compressive strength, minimum C-39 One (1) Day: 2,500 psi Seven (7) Days: 3,000 psi 28 Days: 4,000 psi Bond strength, minimum C-882 One (1) Day: 900 psi Seven (7) Days: 1,800 psi 28 Days: 2,200 psi Linear length change (%), maximum C-157 28 Days wet: +0.04 %a 28 Days dry: -0.04 % Coefficient of thermal expansion (in/in/°F) C-531 3.9 x 10-6 to 7.1 x 10-6 Freeze/thaw resistance @ 300 cycles, minimum C-666 Per Section 509.2.8.4.2, Note 3 aThe maximum allowable expansion can be 0.4% as long as the loca tions where enriched concrete is used can tolerate s uch expansions without exceeding the elastic limit.
533.2.1 3 Rapid-Hardening Cementitious Material
If rapid-hardening cementitious M aterial is used, it shall comp ly with all the fresh and hardened properties of the specif ied concrete, with the additio nal requirement that the product meet the requirements of ASTM C 928 R3 Standard Specifications for Packaged, Dry, Rapid- Hardening Cementitious Materials for Concrete Repair (3,000 psi at three (3) hours, 5,000 psi at one (1) Day, 5,000 psi at seven (7) Days). The Structure ma y be opened to traffic when it has achieved 75% of the design strength. The in-place concrete strength shall be determined in accordance with Section 510.3.5.2, “In-Place Concrete Streng th Measurement.”
533.2.1 4 Water
The Contractor shall provide water in accordance with Section 5 09.2.6, “Water.”
533.2.1 5 Epoxy Repair Materials
533.2.1 5.1 Epoxy Repair Materials – Traffic Bearing Surfaces
Epoxy used in bonding skid-resistant Materials to hardened conc rete and as a binder in epoxy mortars or epoxy concretes used on traffic bearing surfac es (or surfaces subject to thermal or mechanical movements) shall conform to ASTM C881 – T ype III.
533.2.1 5.2 Epoxy Repair Materials – Load Bearing Applications
Epoxy used in load bearing app lications for bonding hardened co ncrete to hardened concrete and other Materials and as a binder for epoxy mortars and concretes shall conform to ASTM C881 – Type IV.
533.2.2 Steel Reinforcement
The Contractor shall provide reinforcing steel in accordance wi th Section 540, “Steel Reinforcement.”
533.2.3 Submittals
The Contractor shall submit manufacturer’s product data sheets at least 14 Days before the start of concrete repair Work that describe the product’s i ntended use in Structure repair to the Project Manager. The submitta l shall include mixing, appli cation, and curing instructions.
533.3 Construction Requirements
Care shall be taken during all repair and removal operations to prevent damage to structural components and reinforcing steel being retained.
533.3.1 Establishment of Repair Areas
The Contract will specify approximate repair locations and quan tities. The Contractor shall field verify, locate and m ark the precise areas of delami nation and repair. The Contractor shall obtain Project Manager’s c oncurrence of established repai r areas and establish estimated pay quantities.
533.3.2 Unsound Concrete Removal
The Contractor shall saw cut all boundaries to 3/4 inch depth, and remove concrete with hand-operated devices, chipping hammers, or pavement breakers t o a uniform depth within each concrete Structure repair area. The Contractor shall only use removal Equipment that has been approved by the Project Manager. The following restrictions appl y to concrete removal tools: 1. It is Acceptable to use pavement breakers of the 60 lb class for full depth removal and for initial removal of deteriorated concrete located above the top mat of rebar. The Contractor shall not use pavement breakers of the 60 lb cla ss over girders. Maximum 30 lb class shall be used for all else. If, in the opi nion of the Project Manager, the use of such devices is detrimental to the integrit y of the adjacent concrete Structure, the Contractor shall discontinue the use of pavement breakers. Requests to use 90 lb class pavement breakers may be submitted to the State Bridge Engineer for consideration; Section 533: Concrete Structure Repair Page 451 2. The Contractor shall not use chipping hammers heavier than t he 15 lb class; and 3. Hydro-demolition may be used upon approval by the Project Ma nager. A Plan must be submitted by the Contractor for review and Acceptance. If removal exceeds 50% of the depth of the deck, the Contractor shall perform a full depth repair. The Contractor shall obtain approval from the Project Manager a fter completing concrete removal before proceeding with surface preparation.
533.3.3 Concrete Surface Preparation and Cleaning
The Contractor shall prepare the surface in conformance with th e manufacturer’s application instructions. If the manufacturer does not specify surface preparation, cleaning or bonding, the Contractor shall conform to the following: 1. Mechanically roughen the existi ng surface using Equipment su ch as chipping hammers and remove loose debris generated by roughening; 2. Abrasive blast all concrete Structure repair bond surfaces; 3. Ensure the surface substrate is clean, sound, and dry. Remo ve substances that may prevent a bond between existing and new concrete. If using acid etchers, concrete cleaners, or degreasers to clean the existing surface, remove them completely after cleaning. Before placing repair Materials, cl ean repair areas with oil-free compressed air or clean pressurized water. The Contra ctor shall place a four (4) inch piece of duct tape every square yard to test for cleanliness. The Department will not allow concrete placement if more than 25% o f the tape surface shows dust coverage; 4. Moisten the substrate with clean water in accordance with Se ction 509.2.6, “Water” and remove excess water to achieve a saturated surface dry cond ition; and 5. Use a bonding method per Section 511.3.7.2, “Bonding New Con crete to Existing.” The Contractor shall verify that both the existing substrate an d the existing concrete around the perimeter of the conc rete Structure repair area is s ound in the presence of the Project Manager. If any unsound concrete is detected, the Cont ractor shall remove that concrete per Section 533.3.2, “ Unsound Concrete Removal.”
533.3.4 Furnishing, Placing, Curing, and Finishing Concrete Str ucture Repair Material
The Contractor shall place, finish and cure the repair Material in conformance with the manufacturer’s application instru ctions. If the manufacturer d oes not specify placement, finishing, and curing of the repair Material; Section 511, “Con crete Structures, and Section 512, “Superstructure Concrete” shall apply as applicable. Epox y repair Materials shall be used in strict conformance with th e Manufacturer’s instructions . With regard to forms, the Contractor shall conform to Section 5 11,”Concrete Structures” and the following: 1. For full depth replacement, the Contractor shall provide for ms to adequately support concrete placed in the full depth repair areas; 2. When stay-in-place forms are present and intact: a. The Project Manager may Accept the utilization of the stay-i n-place forms in lieu of temporary forms; b. The Contractor shall be responsible for determining the stru ctural adequacy of Section 533: Concrete Structure Repair Page 452 the stay-in-place forms; and c. If the stay-in-place forms are damaged beyond Acceptability for re-use during demolition, the Contractor shall remove the unacceptable stay-i n-place form and utilize temporary forms; 3. Any form bulges and/or failures will be cause for rejection and shall be addressed to the satisfaction of the Proj ect Manager at no additional cost t o the Department; 4. All concrete Structure repair forming shall be constructed s o that final finishes match the lines and grades of the surrounding concrete and/or the pro posed new lines and grade per the Contract; 5. The Contractor shall not mix repair Materials within the rep air area; 6. The Contractor shall place mortar or concrete in a continuou s operation for each repair area; 7. For vertical surfaces, the Contractor shall start the Work a t the bottom of the patch and continue upwards, and from one edge to the other to prevent the entrapment of air pockets; and 8. If the repair area abuts or crosses a working joint, the Con tractor shall place a temporary strip of waxed wood or pre-molded filler in the joint before placing repair Material. The Contractor shall remove the strips before the co n c r e t e s e t s . T h e Contractor may also repair areas that occur on both sides of a joint by patching the entire cavity and restoring the joint by saw cutting immediatel y after the repair Material has set, instead of usi ng a temporary vertical insert strip. If specified in the Contract, the Contractor shall Finish expos ed surfaces of piers, abutments, edges of decks and barrier railings, and other speci fied locations to a Class 4 finish in accordance with Section 511.3.8.5, “Class 4, Special Surface Finish,” and Section 548, “Coating of Concrete” after repairs and curing are complet e. The Contractor shall apply penetrating Water Repellent Treatmen t in accordance with Section 532, “Penetrating Water Repellent Treatment.”
533.3.5 Reinforcing Steel
All standard placement and construction requirements shall appl y. The Contractor shall reference Section 540, “Reinforcing Steel,” and the following: 1. If the Contractor exposes corroded reinforcing steel during concrete removal, the Contractor shall preserve exist ing reinforcing steel exposed du ring concrete removal; 2. The Contractor shall use only hand tools such as hammers and chisels to remove the final concrete particl es from reinforcing bars; 3. On decks, if the rebar is exposed, the Contractor shall alwa ys chip at least 3/4 inch deep into the adjacent concrete around the entire bar; 4. On anything other than decks, if the bond between exposed ba rs and adjacent concrete breaks; the Contractor shall chip at least 3/4 inch de ep into the adjacent concrete around the entire bar; 5. The Contractor shall supplement or remove and replace reinfo rcing steel displaying deep pitting or loss of more than 20% of cross-sectional area a s directed by the Project Manager. Any rebar that is abandoned in place shall be prepared in the same manner as the adjacent rebar prior to embedment; 6. The Contractor shall strengthen corroded or damaged existing #5 or smaller bars by splicing an equal sized bar at least two (2) ft longer than the corroded or damaged Section 533: Concrete Structure Repair Page 453 length. The minimum splice length shall be one (1) ft on each end. The State Bridge Engineer will determine the length of lap for larger rei nforcing bars; 7. Any reinforcing steel damage d during concrete removal operat ions by the Contractor shall be supplemented or removed and replaced by the Contractor at no additional cost to the Department; 8. Mechanical couplers may be used in accordance with Section 5 40.3.1.4, “Splicing;” 9. The Contractor shall prepare the surface of the reinforcing steel in conformance with the recommendations of the repair Material manufacturer. In th e absence of direction from the patch Material supplier, the Contractor shal l use abrasive grit blasting or wire brushing to bare metal; 10. The Contractor may leave tight “flash” rust occurring after blast cleaning if Acceptable to the repair Material manufacturer; 11. When epoxy coated bar is present, the Contractor shall repa ir any damage to the epoxy coating prior to embedment; 12. When galvanic anodes are utilized and epoxy coated rebar is present, repair of epoxy coating is not required; 13. The Contractor shall ensure that minimum concrete cover is maintained. Minimum concrete cover shall match the original design or shall be a mi nimum of two (2) inches or shall be as noted in the Contract. 14. Reinforcing bars shall be replaced and/or supplemented with the same bar type as is existing unless otherwise noted in the Contract. All reinfo rcing bar types, including epoxy coated, shall be pai d as “Replacement Reinforci ng Bars.”
533.3.6 Acceptance
The Project Manager will examine repaired areas after the curin g period is completed to ensure soundness of the repairs and complete bonding with the e xisting surface. The Contractor shall remove and replace unacceptable areas at no ad ditional cost to the Department.
533.3.7 Acceptance for 509 Approved Concrete Mixtures
Concrete mixtures that have been approved in accordance with Se ction 509, “Portland Cement Concrete Mix Designs” shall be tested and Accepted in ac cordance with Sections 510, “Portland Cement Concrete,” 511, “Concrete Structures,” an d 512, “Superstructure Concrete” as applicable.
533.3.7 1 Acceptance for Prepackaged, Preblended Cementitious M aterials
Frequency of testing shall be determined by the Project Manager . If testing is required by the Project Manager, three (3) concrete cylinders for 24 hour c ompressive strength shall be made by the Department. It is recommended that testing be perf ormed on the first batch and every third batch thereafter. The water to cement ratio of the tested batch(s) shall be consistent with all other batches.
533.4 Method of Measurement
If the repair depth does not exceed four (4) inches, the Depart ment will measure and pay for the Work by the square yard. For girder Bridges, if the re pair depth exceeds four (4) inches, the Department will pay for the deck repair on a prorat ed rate of 25% of the Bid Item Unit Price for Repair of Concrete Structures per inch deeper th an four (4) inches. For concrete slab Bridges, if the repair depth exceeds four (4) inc hes, the Department will pay for Section 533: Concrete Structure Repair Page 454 the deck repair on a prorated rate of ten percent (10%) of the Bid Item Unit Price for Repair of Concrete Structures per inch deeper than four (4) inches. The Department will measure exposed surfaces before the app lication of the special surface finish.
533.5 Basis of Payment
Pay Item Pay Unit Repair of Concrete Structures Square Yard Replacement Reinforcing Bars Pound
533.5.1 Work Included in Payment
The following Work and items will be considered as included in the payment for the main item(s) and will not be measured or paid for separately: 1. Sounding; 2. Removal of unsound concrete; 3. Removal and replacement of co mpromised reinforcing steel to include epoxy anchoring if required; 4. Disposal of old concrete and debris; 5. Surface preparation of concrete and reinforcing bar surfaces ; 6. Any additional costs associat ed with rapid-hardening concret e; 7. Saw cutting operations; 8. Placement and removal of forms; 9. Compliance with manufacturer’s instructions; 10. Penetrating water repellent tr eatment of repaired concrete surfaces; 11. Bonding agent; 12. Curing; and 13. Grinding, rubbing, and final clean up. Section 534: Epoxy Injection Page 455