Article 1 — Description
Remove and repair unsound, delaminated, or spalled concrete.
Article 2 — Materials
Submit all proposed repair materials for approval. Provide materials in accordance with the Concrete Repair Manual and the following. Item 421, “Hydraulic Cement Concrete” Item 431, “Pneumatically Placed Concrete” Item 440, “Reinforcement for Concrete” DMS -4655 , “Concrete Repair Materials” DMS -6100 , “Epoxies and Adhesives”
2.1 Concrete Repair Materials. Provide repair materials suitable for the appropriate horizontal, vertical, or
overhead application meeting the requirements of DMS -4655 . Use Type C trowel -applied materials in vertical and overhead applications less than 3 in., unless otherwise shown on the plans. Use neat Type A (Rapid) or Type D (Standard) materials in horizontal or form- and-pour applications less than 3 in. thick and extended Type A or Type D for repairs exceeding 3 in. in depth. Type D materials should be used instead of Type A when rapid strength gain is not necessary. Use Type B ultra- rapid hardening materials only if shown on the plans. The Engineer may disallow any product based on its structural compatibility.
2.2 Pneumatically Applied Materials. Pneumatically applied concrete or mortar may be used, if approved, for
any repair thickness. Provide and place pneumatically applied concrete in accordance with Item 431. Prepare trial batches of any proposed repair material and application method as directed.
2.3 Epoxy Mortars. Use Type VIII neat epoxy or epoxy mortar in accordance with DMS -6100 for repairs less
than 1 in. thick unless otherwise shown on the plans.
2.4 Concrete. P rovide Class C concrete for substructures and Class S or Class K concrete for decks, unless
otherwise shown on the plans. For repair of other concrete elements, provide concrete of the class or design strength specified on the plans. Submit a mix design for approval in accordance with Item 421, unless otherwise shown on the plans. Include all pertinent information regarding admixtures. Do not use corrosion -inhibiting admixtures unless shown on the plans or approved.
2.5 Steel . Provide steel pins , studs, or expansion bolts with a minimum diameter of 1/8 in. and a minimum length
of 2 in. to attach reinforcement at the locations shown on the plans or as directed. Provide reinforcing steel, either welded wire fabric or reinforcing bars, as required by this Item or as shown on the plans.
2.6 Mechanical and Adhesive Anchors . When mechanical or adhesive anchors are required to bind repair
material to the parent concrete, provide anchors conforming to one of the following. Provide stainless steel expansion anchors. Other anchors, such as galvanized or zinc -painted metal, may be used with approval . Provide reinforcing steel or threaded stainless steel pins (1/2- inch diameter minimum) anchored in place using a Type III epoxy anchoring adhesive, in accordance with DMS -6100 . 598 3. EQUIPMENT The Engineer may require demonstration of the equipment’s abilities.
3.1 Abrasive Blasting . Provide equipment capable of removing oil, dirt, slurry, curing compound, laitance, and
other similar materials from the surface of the concrete.
3.2 Water Blasting . Provide equipment capable of supplying a minimum pressure at the nozzle end of 3,000 psi
at a minimum flow rate of 3 gpm. Use a 0° rotary, vibratory, or wobble- type nozzle.
3.3 Sawing . Provide equipment capable of sawing concrete to the depth specified when required.
3.4 Power -Driven Chipping Tools . Provide tools not heavier than a nominal 30-lb. class for bulk removal of
concrete.
3.5 Chipping Hammers . Provide chipping hammers not heavier than a nominal 15- lb. class to remove concrete
beneath any reinforcing bars.
3.6 Hand Tools . Provide applicable hand tools for placing, consolidating, striking- off, and finishing stiff plastic
concrete.
Article 4 — Construction
Follow the procedures in accordance with the Concrete Repair Manual unless approved otherwise. The Contractor may propose alternate repair methods for review and approval before commencing work. Submit for approval all materials and methods of application at least 3 weeks before beginning any repair work. Repair locations will be as shown on the plans or as directed. Place repair material while the concrete substrate is in a saturated surface dry (SSD) condition. Obtain an SSD condition by applying a high -pressure water blast to the surface for at least 15 min. An SSD condition is achieved when the surface remains damp until the repair material is applied. The surface must be free of standing water. Remove all free (ponded) water just before placing repair material. Do not use a proprietary epoxy bonding layer instead of an SSD substrate unless approved. If use of a proprietary bonding agent is authorized, mix it in conformance with the manufacturer’s requirements. Use only Department -approved Type V or Type VII material in accordance with DMS -6100 .
4.1 Crack Repair . Repair cracks in accordance with Item 780, “Concrete Crack Repair.”
4.2 Repair of Defective Work. Repair or replace defective areas and patched areas that have debonded after
completion of curing, as directed, at the Contractor’s expense.
Article 5 — Measurement
This Item will be measured by the square foot, in place, as measured on the specified horizontal, vertical , or overhead surfaces of the completed repair . When a repair involves multiple surfaces, such as a corner, measurement will be made of all surfaces repaired. Bridge deck repairs will be measured by the square foot in place of the completed repair. Measurement will be made before blending repair edges with parent material in accordance with the Concrete Repair Manual. 599 6. PAYMENT The work performed and materials furnished in accordance with this Item and measured as provided under “Measurement” will be paid for at the unit price bid for “Concrete Structure Repair” of the kind specified. This price is full compensation for furnishing, placing, and curing all repair materials; removing concrete; saw- cutting; cleaning reinforcing steel; surface preparation; supplying and installing replacement or supplemental reinforcing steel, drive pins, studs, anchors, or expansion bolts; and equipment, labor, tools, and incidentals.