NOTE This standard governs the repair and restoration of existing hardened concrete, including assessment, surface preparation, repair material selection, crack repair, patching, bonded overlays, corrosion mitigation, and protective treatment. (1.1)

NOTE The work covers the full life cycle of a concrete repair: evaluating the cause and extent of deterioration, removing unsound and contaminated material, preparing the substrate to a defined profile, selecting a compatible repair material, placing and curing it, and protecting the finished repair against the mechanism that caused the original distress. A repair specification that addresses placement without addressing cause produces a repair that fails again on the same schedule as the original. (1.2)

NOTE The repair system is selected to match the deterioration mechanism, not merely to refill the visible defect. (1.3)

NOTE Cosmetic spalling, freeze-thaw scaling, carbonation-induced corrosion, chloride-induced corrosion, alkali-aggregate reaction, and overload cracking each demand different materials, preparation, and protection. The assessment that classifies the mechanism is upstream of and governs every selection in this standard. (1.4)

NOTE This standard applies to building structures, parking structures, water and wastewater structures, industrial floors, and bridges held under building specifications rather than highway-agency contracts. (1.5)

NOTE Where a bridge or transportation structure is delivered under a state DOT or FHWA highway contract, that agency's standard specifications and material approval lists govern instead of this standard. This standard is written for repair work procured under building project specifications. (1.6)

NOTE Structural repairs restore or supplement the load path and require engineering of the repair detail, the bond interface, and the reinforcement; non-structural repairs restore cover, surface, and durability without engineered load transfer. (1.9)

NOTE The distinction drives material class, inspection level, and submittal depth. Treating a structural repair as a cosmetic patch — placing mortar over corroded reinforcement in a load-bearing column without an engineered detail — is a safety defect, not a quality defect. (1.10)

NOTE This standard does not cover the following work. (1.11)

NOTE The following scopes are governed by their own standards and are excluded here even where they are encountered on the same project: (1.12)

NOTE ICRI guideline numbers are issued by the International Concrete Repair Institute and are not ASTM or ACI designations; they shall not be cited interchangeably. (2.3)

NOTE The CSP (Concrete Surface Profile) scale and the silane treatment guidance referenced throughout this standard originate in ICRI guidelines, while material specifications and structural provisions originate in ASTM and ACI. Each governs its own domain. (2.4)

NOTE The mockup establishes the achievable surface profile, edge detail, color match, and bond strength against which production repairs are judged, and it surfaces incompatibilities before they are replicated across the structure. (4.3)

NOTE A mockup that passes the pull-off acceptance criteria becomes the contractual standard of workmanship; production repairs that do not match it are rejected. (4.4)

NOTE Special inspection of structural concrete repair shall be coordinated with Special Inspections And Testing in accordance with IBC Section 1705. (4.7)

NOTE IBC Section 1705.3 requires special inspection for concrete work on structural members, and repairs to structural members fall within that scope. Omitting the repair scope from the inspection coordination leaves an inspection gap that can stall closeout or invalidate the repair. (4.8)

NOTE Repair material selection follows from the deterioration mechanism; a patch placed without diagnosing the cause treats the symptom and leaves the driver in place. (5.2)

NOTE Carbonation- and chloride-induced corrosion, freeze-thaw damage, sulfate or chemical attack, alkali-aggregate reaction, and structural overload each leave characteristic patterns. The assessment classifies the mechanism so that material, preparation depth, and protective treatment all respond to it. (5.3)

NOTE The chloride "halo" — contamination that has migrated into sound-looking concrete beyond the visible spall — will drive new corrosion at the repair perimeter if the repair boundary is set only at the visible damage. (5.6)

NOTE This is a well-documented failure mode. Chloride profiling lets the repair boundary be set conservatively beyond the contaminated zone, so the repair does not become the next anode in a corrosion cell. Removing only to the visible spall edge is a primary cause of recurring "ring" spalling around prior repairs. (5.7)

NOTE CSP is a measurable roughness scale from CSP 1 (acid-etched) to CSP 10 (heavy scarification); the repair material's bond depends on it, so an undesignated profile invites under-preparation, debonding, and dispute. (6.3)

NOTE Penetrating sealers need only a light profile (CSP 1-3); bonded overlays need a moderate profile (CSP 3-5); cementitious repair mortars over removed concrete need an aggressive profile (CSP 5-9) produced by scarification or hydrodemolition. Specifying the minimum CSP number per repair type is mandatory, not optional. (6.4)

NOTE A feathered repair edge is the thinnest, weakest part of the repair and the first to debond and ravel under traffic or thermal cycling; the saw-cut perpendicular edge gives the repair a defined, full-thickness boundary. (6.6)

NOTE This single detail prevents a large share of premature edge failures. The saw cut also gives a clean visual boundary for the finished repair. (6.7)

NOTE When repair material cannot flow fully behind an exposed bar, an unfilled void forms at the bar — the exact location where the next corrosion cell starts. (6.10)

NOTE ACI PRC-546 calls for removing concrete to provide clear space behind exposed reinforcement, typically on the order of 3/4 in. (19 mm), so the repair material wraps the bar completely. The required clearance is set by the repair material's maximum aggregate size and placement method. (6.11)

NOTE Repair material placed over actively corroding, scale-bearing reinforcement will not arrest corrosion; the rust must be removed and the bar protected, or the repair simply hides ongoing section loss. (7.3)

NOTE Cleaning the steel and, where specified, applying a corrosion-inhibiting or zinc-rich bar coating addresses the corrosion mechanism. Where chloride contamination is severe or widespread, ACI 222R-compatible cathodic protection or a galvanic anode system may be required as the repair cannot mechanically exclude all chloride. (7.4)

NOTE A protective coating shall be applied to cleaned reinforcement only where it is compatible with the repair material and does not impair the bond of repair material to the bar. (7.6)

NOTE Some bar coatings, applied too thickly, debond the repair material from the steel. The coating, the repair material, and the bonding agent must be an evaluated system. Where a galvanic anode system is used, bar coatings that electrically isolate the steel defeat the anode and shall not be used. (7.7)

NOTE A repair material much stiffer or stronger than the parent concrete concentrates stress at the bond interface and delaminates under thermal cycling; matching, not maximizing, properties is the goal. (8.2)

NOTE Specifying an 8,000 psi repair mortar on 3,000 psi parent concrete is a common over-specification error that drives interface failure. The repair should be modestly stronger than the substrate, not dramatically stronger. (8.3)

NOTE High drying shrinkage is a leading cause of repair debonding and edge cracking; screening materials by ASTM C596 keeps high-shrinkage products out of the repair. (8.7)

NOTE A shrinking repair pulls away from the saw-cut perimeter and the substrate, opening a path for water and chloride. The shrinkage limit is as important as the strength minimum for a durable repair. (8.8)

NOTE Many prepackaged repair mortars develop a full monolithic bond to a properly prepared, saturated-surface-dry substrate and are degraded by an epoxy bonding agent applied beyond its open time; the bonding agent is not a universal upgrade. (9.2)

NOTE Following the repair material manufacturer's interface requirement is mandatory. A cementitious scrub-coat keys the mortar to the substrate; an epoxy bonding agent provides a high-strength bond for selected systems but must be overcoated within its open time or it becomes a bond-breaker. (9.3)

NOTE A standard epoxy bonding agent applied to a wet surface does not wet out the concrete and fails to bond — a frequent and avoidable defect on water and wastewater work; the moisture condition limit is part of the specification, not a field judgment. (9.7)

NOTE Where the substrate cannot be dried — submerged or continuously wet structures — a moisture-tolerant or moisture-insensitive bonding agent must be explicitly specified, or a cementitious scrub-coat used instead. (9.8)

NOTE Partial-depth repairs (above the reinforcement) and full-depth repairs (through the section) shall be detailed separately; full-depth repairs require formwork, through-section concrete, and engineering review. (10.1)

NOTE A partial-depth repair restores cover over sound concrete; a full-depth repair replaces a section of the member and is structural. The removal depth, edge detail, material class, and inspection level differ accordingly. (10.2)

NOTE Specifying a repair thickness below 1 in. forces a feathered placement that debonds and ravels; every prepackaged cementitious repair mortar carries a 1 in. (25 mm) minimum for this reason. (10.4)

NOTE Where the available depth is less than 1 in., either deepen the removal to reach the minimum or select a thin-section material (such as an epoxy mortar) qualified by the manufacturer for the available thickness. "Minimum 3/4 inch" is a recurring specification error that generates RFIs and callbacks. (10.5)

NOTE Where the repair fills a formed cavity or void rather than a surface patch, non-shrink cementitious grout per ASTM C1107 may be used in coordination with Non Shrink Grout. (10.8)

NOTE The boundary is by application, not material: surface and section repair is governed here; filling a discrete formed cavity or under-bearing void with a flowable non-shrink grout follows the grouting standard. (10.9)

NOTE A dormant crack can be rigidly bonded back together; an active crack will move again and will re-crack a rigid repair, so the two require opposite material properties. (11.2)

NOTE Dormant structural cracks are restored to monolithic action by rigid epoxy injection. Active or moving cracks require a flexible polyurethane injection or must be routed and sealed as a movement joint, because a rigid epoxy across a moving crack simply relocates the crack to the adjacent sound concrete. (11.3)

NOTE Epoxy crack injection restores structural continuity only when the resin penetrates the full depth of the crack; surface-only injection leaves the section uncracked in appearance but uncorrected in fact. (11.6)

NOTE Crack widths from approximately 0.002 in. (0.05 mm) up to about 0.5 in. (12.7 mm) are addressable by injection. Port spacing, injection sequence, and surface sealing are set so the resin advances continuously through the crack rather than channeling. (11.7)

NOTE Routed-and-sealed crack repairs shall be detailed and sealed in coordination with Joint Sealants where movement accommodation is required. (11.10)

NOTE Routing the crack into a chase and installing a backer rod and movement-class sealant converts the crack into a controlled joint. Below-grade and water-bearing cracks may also require coordination with Below Grade Waterproofing or Fluid Applied Waterproofing for the surface protection. (11.11)

NOTE Bonded overlays shall be classified as bonded cementitious, bonded polymer-modified, or unbonded overlay, with the bond requirement and minimum thickness designated for the type. (12.1)

NOTE A bonded overlay relies on a tested bond to the prepared substrate to act compositely; a polymer-modified overlay improves bond and reduces permeability; an unbonded overlay is isolated from the substrate and behaves as a separate slab. The type drives preparation, bond testing, and thickness. (12.2)

NOTE Placing an overlay over a substrate that has not been pull-off tested transfers any hidden delamination, low-strength layer, or unsound zone straight up into the new overlay, which then debonds over the defect. (12.5)

NOTE The pull-off test on representative prepared areas is the gate that confirms the substrate can carry the overlay. Areas failing the minimum tensile strength are repaired before the overlay is placed. (12.6)

NOTE Where fiber-reinforced polymer (FRP) strengthening is included in the repair scope, it shall be designed in accordance with ACI 440.2R by the Engineer of Record. (13.1)

NOTE Externally bonded carbon (CFRP) or glass (GFRP) fabric with an epoxy saturant supplements the flexural or shear capacity of a deteriorated member. FRP is a specialized structural sub-scope: the substrate repair, the surface profile, the laminate design, and the bond all govern its performance, and it is included here only as part of an engineered repair. (13.2)

NOTE A protective surface treatment shall be specified for repairs in chloride-exposed, freeze-thaw, or chemically aggressive environments to slow re-deterioration of the repair and adjacent concrete. (14.1)

NOTE A repair that is not protected against the mechanism that caused the original distress will deteriorate on the same path. Penetrating silane/siloxane sealers reduce chloride and water ingress without forming a film; elastomeric and traffic-bearing membranes bridge fine cracks and exclude water on horizontal surfaces. (14.2)

NOTE Surface treatment shall be applied only after the repair material has cured sufficiently for the treatment per the manufacturer's requirements, and to a surface profile compatible with the treatment (CSP 1-3 for penetrating sealers per ICRI 310.2R). (14.5)

NOTE Applying a penetrating sealer to green repair material or to a profile that is too tight prevents proper penetration. Where a film-forming coating or membrane is applied, surface cleanliness and profile follow SSPC-SP 13 / NACE No. 6. (14.6)

NOTE Rapid-set repair materials lose working time rapidly as temperature rises, and above 90°F (32°C) the material can stiffen before it is placed and finished; epoxies often have a narrower window still. (15.3)

NOTE The pot life of crack injection resins and epoxy mortars at 73°F (23°C) is on the order of 15 to 45 minutes and shortens sharply with temperature. Hot-weather work requires confirmed manufacturer procedures, reduced batch sizes, and pre-cooling; the field cannot improvise around an exceeded temperature limit. (15.4)

NOTE Repair durability depends as much on curing as on the mix; an under-cured rapid-set mortar gains less strength, shrinks more, and debonds, undoing the rest of the specification. (16.3)

NOTE Rapid-set materials reach return-to-service strength quickly but still require protection against early moisture loss. The curing method must match the material — some prepackaged materials are degraded by membrane curing compounds and require wet cure only. (16.4)

NOTE Rapid-set repair materials may permit foot traffic in 1 to 4 hours and vehicular traffic in 4 to 24 hours, but these times are temperature-dependent and shall be confirmed against the product data sheet for the actual conditions. (16.6)

NOTE Returning a repair to traffic before it has gained adequate strength loads the bond interface prematurely and is a common cause of early failure on parking and industrial floor repairs. (16.7)

NOTE Two-component resins are reactive and temperature-sensitive; out-of-date or temperature-abused resin cures incompletely or off-ratio, producing a repair that looks correct but performs below specification. (17.4)

NOTE Shelf-life and storage-temperature compliance is part of material acceptance, not a formality. Batch and lot records tie each placed repair back to a conforming material. (17.5)

NOTE Sounding (chain drag or hammer) is a fast, full-coverage screen for debonded repairs that pull-off testing samples only locally; the two together confirm both global and local bond. (18.4)

NOTE A repair can pass an isolated pull-off test and still be debonded a few inches away. Systematic sounding across the repair area catches the hollow zones that point testing misses. (18.5)

NOTE A repair warranty is only meaningful when the cause of deterioration was addressed; a warranty on a patch over unremediated corrosion warrants the symptom, not the structure. (19.3)

NOTE The warranty terms should reflect the protective treatment reapplication schedule — penetrating sealers, for example, are not permanent and require periodic reapplication to maintain protection. (19.4)