Specialist · 10 checks

Concrete Repair
QA inspection checklist

Concrete repair and protection quality audit.

Every check below carries what good looks like, when it passes, the standard it comes from and the defects that usually fail it. That guidance is what turns a tick-box into an inspection.

Preparation

  1. 1.
    Defective concrete removed to sound substrate
    What to look forAll carbonated, chloride-contaminated, or delaminated concrete removed by hydro-demolition or breaker. Sound substrate confirmed by hammer / chain dragging. Reinforcement exposed at least 20 mm behind bar where corroded. Photo record of breakout extent.
    Acceptable whenPer BS EN 1504-9 / Concrete Society TR 69: removal beyond visible damage to sound substrate; behind reinforcement by ≥ 20 mm or ≥ 1.5 × bar diameter (whichever greater) where corrosion present.
    StandardBS EN 1504-9:2008 — Products and systems for the protection and repair of concrete structures. Concrete Society TR 69 — Repair of concrete structures.
    Common defectsRemoval stopped at visible damage — carbonation / chloride remainsReinforcement not exposed behind — re-corrosion shortlyHammer-and-chisel preparation leaves micro-cracksHydro-demolition pressure too high — sound substrate damagedNo record of breakout extent
  2. 2.
    Reinforcement exposed, cleaned, and treated
    What to look forExposed reinforcement grit-blasted to Sa 2 (visually clean to base metal). Loss of section measured — replaced if > 25% loss. Anti-corrosion primer / zinc-rich coating applied if specified.
    Acceptable whenPer BS EN 1504-7 / Concrete Society TR 69: reinforcement cleaned to ISO 8501-1 Sa 2 minimum; ≤ 25% section loss tolerated, more requires replacement / supplementary; anti-corrosion primer if specified.
    StandardBS EN 1504-7:2006 — Reinforcement corrosion protection. Concrete Society TR 69.
    Common defectsReinforcement still scaly — repair failsSection loss > 25% not addressedAnti-corrosion primer not applied where specifiedWire-brushed instead of blast-cleanedNo measurement of section loss
  3. 3.
    Breakout profile correct for repair system
    What to look forBreakout edges square (vertical / undercut) — not feathered. Edge depth minimum per repair material (typically 25 mm). No sharp internal angles. Substrate textured (CSP 5-9) to ICRI guidance for mechanical key.
    Acceptable whenPer BS EN 1504-10 / ICRI Guideline 310.2R / TR 69: edges square or undercut to mechanical key; minimum depth ≥ 25 mm or per repair material; CSP 5-9 (medium-coarse) for repair mortar bond.
    StandardBS EN 1504-10:2017 — Site application. ICRI Guideline 310.2R — Concrete Surface Profile. Concrete Society TR 69.
    Common defectsFeathered edge — repair material thin, failsInternal angles sharp — stress concentration, cracksCSP too smooth — no mechanical keyDepth < 25 mm — repair mortar cannot achieve coverProfile not textured — bond fails
  4. 4.
    Substrate primed per manufacturer requirements
    What to look forBonding primer (cementitious slurry, latex, or epoxy) applied per repair system TDS. Coverage uniform. Applied "wet-on-wet" before mortar where SBR / latex; allowed to cure to tacky for epoxy.
    Acceptable whenPer BS EN 1504-3 / TDS: substrate pre-wetted (saturated surface dry) before cementitious primer; primer applied per product instructions; mortar applied within open time of primer.
    StandardBS EN 1504-3:2005 — Repair mortars. Manufacturer TDS.
    Common defectsPrimer skipped — bond failsPrimer dried before mortar applied — bond compromisedSubstrate dry — primer absorbed too quicklyWrong primer type for systemNo record of primer use

Repair

  1. 5.
    Repair mortar matches specification
    What to look forRepair material per BS EN 1504-3 — Class R3 (structural) or R4 (high-performance structural). Branded product matching design — Sika MonoTop, BASF MasterEmaco, Fosroc Renderoc. Class R reactivity per product.
    Acceptable whenPer BS EN 1504-3:2005: Class R3 (compressive ≥ 25 MPa) or R4 (≥ 45 MPa) per design; PCC (polymer-modified cementitious) or CC (cementitious) per environment. CE/UKCA mark.
    StandardBS EN 1504-3:2005 — Concrete repair products. CE/UKCA per Construction Products Regulation.
    Common defectsR3 used where R4 specified — strength inadequateGeneric mortar substitutedWrong reactivity (PCC where CC needed for chemical resistance)Out-of-date material — set fast / poor performanceNo CE/UKCA mark
  2. 6.
    Application method correct (hand/spray)
    What to look forApplication by hand-trowel (small repairs), formed and poured (large), or sprayed (vertical / overhead). Layered if depth exceeds maximum single layer (typically 30-50 mm). Compaction to remove voids.
    Acceptable whenPer BS EN 1504-10 / TDS: application method per repair material and geometry; layered application within max single-layer depth; compaction by trowel or vibration to remove air.
    StandardBS EN 1504-10:2017. Manufacturer TDS.
    Common defectsSingle-pass application > max depth — slumpingHand-trowel where spray needed for overheadInadequate compaction — voidsLayers not bonded — delaminationWet-on-dry instead of wet-on-tacky
  3. 7.
    Layer thickness within limits
    Record: Thickness (mm)
    What to look forLayer thickness within product min and max — typically 5-50 mm for hand-applied, 10-80 mm for sprayed. Thicker repairs in multiple layers with mechanical key between (scratch finish).
    Acceptable whenPer TDS: layer thickness within product limits; multiple-layer with scratch-key between for thicker. Cover to reinforcement per design.
    StandardBS EN 1504-3:2005. BS EN 1504-10:2017. Manufacturer TDS.
    Common defectsLayer thicker than max — slumping / shrinkage cracksLayer thinner than min — coverage / strength lossNo scratch finish between layers — delaminationInsufficient cover to rebar after repairLayer step visible — finish fails
  4. 8.
    Curing regime followed
    What to look forCuring per TDS — water mist, wet hessian, polythene cover, or curing membrane. Duration per product (typically 3-7 days). Protection from sun, wind, frost. Curing record kept.
    Acceptable whenPer BS EN 1504-10 / TDS: curing duration depends on product and ambient; typical PCC repair 3-7 days. Protection from accelerated drying, frost, freeze-thaw.
    StandardBS EN 1504-10:2017. Concrete Society TR 67. Manufacturer TDS.
    Common defectsNo curing — surface dehydrates, cracksCuring duration too shortDirect sun on repair — surface cracksFrost during cure — repair failsNo curing record
  5. 9.
    Surface finish acceptable
    What to look forRepair surface flat with adjacent concrete. Trowel finish or rendered to match. No proud spots, no hollows, no shrinkage cracks. Colour reasonable match (PCC repairs typically darker).
    Acceptable whenPer project specification: repair flush with surrounding concrete; surface texture match where decorative; no shrinkage cracks > 0.3 mm. Colour difference acceptable for non-visual.
    StandardBS EN 1504-10:2017. Project specification.
    Common defectsRepair stands proud — visual faultHollow repair — water collectsShrinkage cracks > 0.3 mm — durability impairedColour mismatch — aesthetic failTrowel marks visible
  6. 10.
    Pull-off adhesion test passed
    Record: MPa
    What to look forPull-off (bond) tests per BS EN 1542 at frequency in spec. Calibrated dolly bonded to repair, pulled to failure with calibrated tester. Failure mode noted (cohesive in concrete = good; adhesive at interface = bad).
    Acceptable whenPer BS EN 1542 / BS EN 1504-3: pull-off ≥ 0.8-1.5 MPa for Class R2/R3, ≥ 2.0 MPa for R4. Failure preferably cohesive in substrate. Test frequency 1 per 50-100 m².
    StandardBS EN 1542:1999 — Measurement of bond strength by pull-off. BS EN 1504-3:2005.
    Common defectsPull-off below threshold — bond failsAdhesive failure at interface — preparation faultDolly bond fails before substrate — invalid testTest frequency low — areas untestedNo record of test

Questions people ask

What is a concrete repair QA inspection for?

To record that the work was checked against the specification before it was covered up or handed over: a pass or fail against each item, a measurement where one matters, and a photo where it failed. It is the evidence a client's quantity surveyor or clerk of works asks for, and the thing that settles the argument at final account.

What standards does this checklist check against?

Each item names its reference. On this checklist that includes BS EN 1504-9:2008, BS EN 1504-7:2006, BS EN 1504-10:2017, BS EN 1504-3:2005, BS EN 1504-10:2017. Manufacturer TDS., BS EN 1504-3:2005. BS EN 1504-10:2017. Manufacturer TDS.. The contract specification and the approved drawings always take precedence over a general standard; where they say something stricter, inspect to that.

Who signs a QA inspection off?

The person who carried out the check, named and dated, and where the contract calls for it the client's representative as a witness. The signature records that the check was done and what was found. It is not a warranty of the work.

How many items are on it, and do I have to use them all?

10 checks across 2 sections. Delete what does not apply to the job and add anything the specification asks for that is not here. A checklist that has plainly been thought about carries more weight than a long one nobody read.

Is this useful for a subcontractor as well as a main contractor?

More so. The subcontractor is the one who gets asked to come back and open something up. A signed inspection sheet with photos at the time is the cheapest insurance on a construction site.

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