Concrete Repair Decision Tree per ACI 562

Why this matters

ACI 562 is the only adopted code in the United States that addresses assessment and repair of existing concrete structures as a code document rather than a guide. When a foundation contractor scopes a crack injection, a section replacement, or a CFRP wrap, the work falls under ACI 562 jurisdiction whether the contractor invokes the document or not. Engineers reviewing repair drawings cite it. Building officials accepting permitted repair work reference it. This article maps the decision tree for the most common residential and light commercial concrete repair scenarios so the scope, the materials, and the QA all line up with the code before the engineer of record (EOR) shows up to review.

Establish the repair classification

ACI 562 classifies repairs into three categories that drive the depth of analysis and the documentation requirements:

• Repairs to existing structures without strength or stability impact (Category 1). Crack sealing for water-tightness only, surface coatings, cosmetic patching. Minimal analysis required.
• Repairs that affect serviceability or durability but not strength or stability (Category 2). Sealing active cracks, replacing spalled cover concrete, applying corrosion-inhibiting coatings. Analysis to confirm the repair restores the intended service condition.
• Repairs that restore or modify strength or stability (Category 3). Section enlargement, member replacement, post-tensioned strengthening, CFRP flexural or shear reinforcement, underpinning, pier installation. Full engineering analysis per ACI 562 Chapter 6 required.

A repair contractor cannot self-classify Category 3 work as Category 1 to skip the engineering. Building officials and insurance adjusters check this exact path because the documentation difference is significant.

Condition assessment

ACI 562 Chapter 5 requires a documented condition assessment before repair design. The minimum residential assessment includes:

• Visual inspection with photo documentation per ACI 364.1R protocol
• Crack mapping with crack width measured (crack comparator or optical crack scope), location plotted on the foundation drawing
• Cover meter survey to identify rebar location and depth (Hilti PS 300 or Proceq Profometer)
• Half-cell potential survey if corrosion is suspected (Proceq Canin+, per ASTM C876)
• Carbonation depth test (phenolphthalein indicator on a freshly fractured surface, per RILEM CPC-18)
• Chloride content sampling at two depths if marine, deicing, or chemical exposure is documented

The assessment report is the basis for the EOR's repair design. Skipping it is the single most common code-compliance failure on foundation repair permits.

Crack repair selection

Crack treatment depends on whether the crack is structural, whether it is active, and whether moisture is present:

• Non-structural, dormant, dry: surface sealant (BASF MasterEmaco P 124 or Sika Sikadur 31 Hi-Mod Gel surface seal) is sufficient
• Non-structural, dormant, wet: hydrophilic polyurethane injection (Sika SikaFix HH or Avanti AV-202) seals against water
• Structural, dormant, dry: low-viscosity epoxy injection (Sika Sikadur 35 Hi-Mod LV or Simpson Strong-Tie ETI-LV) bonds the crack faces and restores tensile continuity
• Structural, active: do not injection-rigid-bond. Install a flexible joint (saw cut to dimensioned width, install a backer rod, seal with a polyurethane joint sealant such as Sika Sikaflex 1a) so future movement does not re-crack the substrate

Active cracks are identified by crack monitors (Avongard or Crack Monitor Co.) read over 90 days. A crack with measured movement over 0.005 inch in 90 days is active.

Cover repair and spall replacement

Spalled concrete with corroded rebar requires removal of unsound concrete behind and 3/4 inch around the bar, abrasive blast to white metal on the rebar (SSPC-SP 5 or 10), application of a zinc-rich primer or migrating corrosion inhibitor, and repair with a polymer-modified cementitious mortar (BASF MasterEmaco S 488 or Sika MonoTop 622). For overhead or vertical patches, the repair mortar must carry a vertical and overhead designation (R3 or R4 per EN 1504-3, or the manufacturer's equivalent classification).

Hand-applied vs form-and-pour: hand-applied is appropriate for repair volumes under 1 cubic foot per patch; form-and-pour is required above that to avoid trapped air and to keep the cement-to-water ratio within spec.

Section enlargement and underpinning

Adding new concrete to existing concrete for strength enhancement (Category 3 repair) requires:

• Surface preparation per ICRI Guideline No. 310.2 to a CSP 5 to CSP 9 profile by hydroblasting, scarifying, or shot blasting
• Anchorage of new reinforcement to the existing concrete with epoxy anchors (Hilti HIT-RE 500 V3 or Simpson SET-XP) sized and embedded per the EOR's design and the anchor adhesive ICC-ES report
• A bonding agent or saturated-surface-dry condition at the substrate before the new pour, per the design specification
• Vibration of the new concrete to ensure consolidation against the existing surface

Underpinning piers attached to the existing foundation are also Category 3 work. The bracket-to-foundation bolts are engineered anchors and must be designed per ACI 318 Chapter 17 anchorage provisions, then verified per ACI 562 for the repair condition.

Repair material qualification

ACI 562 requires that repair materials be qualified to the relevant standards before use. The minimum documentation in the contractor's QA file:

• Manufacturer technical data sheet for every product
• Current ICC-ES Evaluation Service Report (ESR) for anchors and structural adhesives
• ASTM C928 or C1583 test data for repair mortars
• Compatibility test data when multiple products are layered (sealer over patching mortar, coating over concrete, etc.)

Mix-design submittals for new concrete used in repair, including cement type, water-cementitious ratio, admixtures, and aggregate gradation, are required for any pour over 1 cubic yard.

Inspection and acceptance

Owner-engaged special inspection per ACI 562 Chapter 7 is required for Category 3 work and for any Category 2 work that supports structural elements. The inspection scope, the inspector's qualifications (ACI Certified Concrete Construction Inspector minimum), and the inspection frequency are part of the contract.

Final acceptance includes documented in-place strength testing on a sample of repairs (pull-off tests per ASTM C1583 for bonded patches, core compressive strength per ASTM C42 for section enlargement, anchor proof tests per ASTM E488 on a percentage of installed anchors).

References

• ACI 562-21 Code Requirements for Assessment, Repair, and Rehabilitation of Existing Concrete Structures
• ACI 318-19 Building Code Requirements for Structural Concrete
• ACI 364.1R-19 Guide for Evaluation of Concrete Structures Before Rehabilitation
• ICRI Guideline No. 310.2R-2013 Selecting and Specifying Concrete Surface Preparation
• ASTM C876 Standard Test Method for Corrosion Potentials of Uncoated Reinforcing Steel in Concrete
• ASTM C1583 Standard Test Method for Tensile Strength of Concrete Surfaces and the Bond Strength of Repair Materials
• Hilti HIT-RE 500 V3 Adhesive Anchor ICC-ES ESR-3814 (current revision)
• Sika and BASF Master Builders Solutions structural repair product technical data (2024 release)