ICRI CSRT Grade 1 cheat sheet

Concrete is a composite of cement paste (binder + water) and aggregate; typical hardened paste porosity 10-25% by volume governs permeability, not total porosity alone.

Water/cementitious ratio rule: each 0.01 increase in w/cm raises capillary porosity and permeability; w/cm above ~0.45 leaves continuous capillary pores that permit fluid ingress.

Carbonation: CO2 dissolves in pore water forming carbonic acid, which converts Ca(OH)2 to CaCO3 and lowers pore-solution pH from ~12.5-13.5 to below 9, depassivating steel; carbonation depth scales roughly with the square root of exposure time.

Chloride-induced corrosion: chloride threshold commonly cited near 0.4% by mass of cement (acid-soluble) or 0.05-0.08% by mass of concrete for the critical threshold; chlorides destroy the passive film locally, producing pitting.

Freeze-thaw damage requires critical saturation (commonly cited ~91% degree of saturation) plus repeated cycles; air entrainment (4-8% for moderate/severe exposure) provides relief voids.

Alkali-silica reaction (ASR): reactive silica aggregate + high pore-solution alkali + moisture forms expansive gel; diagnosis relies on cracking pattern, gel presence, and the gel's swelling behavior, not on crack width alone.

Sulfate attack: external sulfates react with C3A hydrates to form ettringite and with Ca(OH)2 to form gypsum, causing expansion and softening; Type V (or sulfate-resisting) cement limits C3A to reduce risk.

Delayed ettringite formation (DEF) occurs when concrete is cured above ~70 degrees C (158 degrees F) early in life, then re-exposed to moisture; it is internal sulfate attack, distinct from external sources.

Deterioration mechanisms are classified as physical (freeze-thaw, salt crystallization, abrasion, thermal cycling) or chemical (carbonation, chloride ingress, sulfate attack, ASR, acid attack); the repair strategy must target the controlling mechanism.

Portland-cement-based repair mortars must be compatible in modulus of elasticity, thermal expansion coefficient, and drying shrinkage with the substrate; a stiffer patch concentrates stress at the bond line.

Shrinkage-compensated (Type S or expansive) repair materials are specified where patch dimensions are large enough that restrained drying shrinkage would otherwise crack or debond the repair.

Polymer-modified mortars (latex- or redispersible-powder-modified) improve bond, tensile strength, and impermeability; polymer content is reported as a percentage of cement weight and must match the manufacturer's stated dosage.

Epoxy repair materials are high-strength, low-permeability, and essentially non-shrinking but have a higher modulus and thermal coefficient than concrete; they are unsuitable for damp substrates or where vapor transmission is required.

Bonding agents: cementitious slurry must be applied to a saturated-surface-dry (SSD) substrate while still glossy; epoxy bonding agents require a dry, sound surface and have a defined open time.

Repair material selection depends on exposure class (e.g., chloride, sulfate, freeze-thaw, chemical), substrate moisture condition, service temperature range, and whether the repair is structural or cosmetic.

Galvanic compatibility matters: dissimilar metals in contact (e.g., carbon steel and stainless steel) can drive corrosion; isolation or compatible hardware is required in chloride environments.

Cathodic protection and chloride extraction are electrochemical options; they require electrical continuity of the steel and a suitable electrolyte, and are selected when chloride contamination is widespread rather than localized.

Cementitious repair materials should be cured per manufacturer instructions; water demand must not be increased in the field, since added water raises w/cm and reduces strength and durability.

Sound concrete removal must extend to the depth where remaining concrete is sound and uncontaminated; the boundary is verified by sounding (hammer tap) and by visual inspection of the exposed substrate.

Hydrodemolition (high-pressure water jetting) removes concrete without inducing microcracking in the remaining substrate and can remove chloride-contaminated concrete to a controlled depth.

Mechanical methods (scarifying, milling, grinding, abrasive blasting) leave a roughened profile; the profile must be deep enough to develop mechanical bond but must not leave fractured aggregate.

The edge of a repair should be cut square (minimum depth typically 10-13 mm / 0.5 in.) to avoid feather-edging, which produces a thin, weak edge that fails under shrinkage and traffic.

Exposed reinforcing steel must be cleaned to a recognized standard; SSPC-SP 10/NACE No. 2 (near-white) or SSPC-SP 6/NACE No. 3 (commercial blast) are commonly referenced for repair work.

Chloride contamination must be assessed before and after preparation; acid-soluble chloride content is measured on samples taken at the depth of the steel location.

Surface preparation for bonding: substrate should be saturated-surface-dry for cementitious materials; free water on the surface dilutes the bonding slurry, and a dry substrate absorbs water from the repair material.

Dust and debris removal is required after mechanical preparation; residual dust blocks bond, and oil or grease must be removed before any abrasive work, since blasting drives contaminants into the surface.

Concrete removal around reinforcement must expose the full circumference of the bar to permit cleaning and to allow repair material to encapsulate the bar; half-exposed bars create a crevice that traps moisture.

Patch repair sequence: remove deteriorated concrete, clean steel, restore steel section if required, apply bonding agent, place repair material, finish, and cure; skipping any step compromises the bond.

Form-and-pour and shotcrete placements are used for large-volume repairs; shotcrete requires a competent nozzleman and typically a higher cement content with a lower w/cm than cast-in-place.

Dry-pack mortar is a low-water-content, tamped-in-place mix used for small, deep patches and for filling around bolts; its low w/cm minimizes shrinkage but requires a clean, rough, SSD substrate.

Overhead and vertical repairs need thixotropic or low-slump materials that resist sagging; placement must be done in lifts to avoid voids and to permit compaction.

Curing methods include moist curing, curing compounds, plastic sheeting, and water spray; curing duration is typically specified as a minimum (commonly 7 days for Type I cement, longer for blended cements).

Curing compound must be compatible with subsequent finishes; some compounds interfere with adhesion of coatings, and their use must be coordinated with the coating manufacturer.

Post-tensioning and structural repairs require verification of the existing reinforcement and the load path before removal; temporary shoring and load transfer are documented in the repair plan.

Crack repair methods: gravity-fed epoxy injection for structural cracks (widths typically 0.2-0.3 mm and larger), routing and sealing for moving cracks, and stitching for large structural cracks.

Joint and spall repair must restore the profile and drainage; water ponding at a repair accelerates freeze-thaw and corrosion, so the finished surface should shed water.

Pre-construction condition survey documents crack maps, delamination extent, chloride content, and carbonation depth; it establishes the baseline against which repair performance is judged.

Delamination detection uses chain dragging or hammer sounding; a hollow sound indicates a debonded layer, and the surveyed extent is mapped on the structure.

Half-cell potential testing (ASTM C876) maps corrosion activity; potentials more negative than about -350 mV vs. copper-copper sulfate indicate a high probability of active corrosion.

Cover meter (pachometer) surveys locate reinforcement and measure cover depth; insufficient cover is a leading cause of chloride-induced corrosion and is a common repair driver.

Pull-off testing (ASTM C1583 or similar) measures tensile bond strength of a repair; a minimum bond strength is specified in the repair design, and failure should occur in the substrate, not at the bond line.

Slant shear testing (ASTM C882) evaluates bond strength of repair materials to a substrate; it is a laboratory method used to qualify a repair material.

Core sampling provides compressive strength and petrographic information; cores must be taken from representative locations, and the hole must be repaired to the same standard as the surrounding concrete.

Chloride content testing uses acid-soluble or water-soluble extraction; results are reported as a percentage of cement or concrete mass and compared to the specified threshold.

Inspection records must be traceable: mix design, batch tickets, placement dates, curing method, test results, and photographs are retained as part of the repair documentation.

Silica exposure: crystalline silica from cutting, grinding, and blasting is a respirable hazard; controls include wet methods, local exhaust ventilation, and respiratory protection, with exposure limits set by OSHA (29 CFR 1926.1153).

Lead-based paint on older structures requires lead-safe work practices and worker protection under OSHA's lead standard (29 CFR 1926.62); containment and waste characterization are required.

Abrasive blasting media and spent grit may be hazardous waste; disposal must follow applicable regulations, and the waste stream should be characterized before disposal.

Confined space entry (e.g., tanks, vaults, pits) requires atmospheric testing, ventilation, a permit, and a rescue plan under OSHA 29 CFR 1926 Subpart AA.

Fall protection is required for work at heights; guardrails, personal fall arrest systems, and safe access are documented in the site-specific safety plan.

Environmental compliance includes stormwater protection, dust suppression, noise limits, and proper handling of wash water from concrete operations, which is highly alkaline.

Documentation should include as-built repair drawings, material submittals and manufacturer data, test reports, daily field reports, and a photographic record of pre- and post-repair conditions.

Warranty and maintenance documentation should identify the repair scope, materials used, and recommended inspection intervals so the owner can plan future maintenance.

Worker training and certification records (e.g., ACI certification for field technicians, SSPC/NACE for coatings) are part of the quality and safety documentation package.