Concrete Structure Inspection

Per EN 206 and EN 13670, concrete must conform to the specified strength class (e.g., C25/30, C30/37). Conformity is assessed on standard cube or cylinder specimens tested at 28 days per EN 12390-3. The delivery note must state the concrete class, exposure class, and consistency class.

1. Verify delivery notes state correct strength class (e.g., C25/30) matching structural design

2. Check that test cubes/cylinders were cast during pouring per EN 12390-1

3. Review 28-day test results — mean strength must exceed fck + margin per EN 206 Table 14

4. Verify exposure class matches environmental conditions (XC, XD, XS, XF, XA classes)

5. Check consistency class (S1–S5 slump or F1–F6 flow) on delivery

- Concrete delivered with wrong strength class

- Test specimens not taken or improperly cured

- Water added on site reducing strength class

- Exposure class not matching actual conditions (e.g., XF class in freeze-thaw areas)

Per EN 1992-1-1 Section 4.4.1, minimum concrete cover (cnom) depends on exposure class, structural class, and bar diameter. Typical cnom ranges from 25mm (XC1) to 55mm (XS3). Reinforcement must be placed per design drawings with tolerances per EN 13670 Table 11.

1. Measure concrete cover with a covermeter — must meet cnom from design (typically 25–55mm)

2. Verify bar diameters match structural drawings

3. Check bar spacing matches design — use tape measure between bars

4. Verify lap lengths meet requirements (per EN 1992-1-1 Section 8.7, typically 40–60 bar diameters)

5. Check that spacers/chairs maintain correct cover during pouring

- Insufficient cover leading to corrosion risk

- Wrong bar diameters or missing bars

- Lap lengths too short at critical sections

- Spacers displaced during concrete pouring

Per EN 13670 Section 8, formwork must be rigid enough to maintain shape during concreting. Surface finish classes are F1 (basic) to F5 (special). Tolerances for completed elements are given in EN 13670 Table 10 — e.g., columns: verticality ±h/300 (min 15mm), beams: ±L/500.

1. Check dimensional accuracy of completed elements against EN 13670 Table 10

2. Verify column verticality with a plumb line or level — tolerance ±h/300

3. Inspect surface for honeycombing, blowholes, or cold joints

4. Assess surface finish class against specification

5. Check that formwork ties and inserts are properly sealed or removed

- Honeycombing from poor vibration or too-dry mix

- Cold joints from delayed concrete pours

- Formwork deformation under hydrostatic pressure

- Visible formwork tie holes not properly sealed

Per EN 13670 Section 8.5, concrete must be cured for a minimum period depending on ambient temperature and cement type. For CEM I at 15°C, minimum curing is 3 days for exposure class XC1, 7 days for XC2–XC4. Early thermal cracking must be controlled per EN 1992-1-1 Section 7.3.

1. Verify curing method (wet curing, curing compound, or membrane) is applied

2. Check that curing started immediately after finishing (within ~1 hour)

3. Confirm curing duration matches exposure class and ambient temperature

4. In cold weather (<5°C), verify insulation or heating measures are in place

5. Check for early-age thermal cracking in thick sections

- No curing applied — rapid surface drying causes shrinkage cracking

- Curing stopped too early

- Cold weather concreting without protection (frost damage)

- Thermal cracking in thick pours (>500mm) without cooling measures