Concrete Structure Inspection

In accordance with EN 206 and EN 13670, the concrete must comply with the specified strength class (e.g. C25/30, C30/37). Conformity is assessed using standardised cylindrical or cubic specimens tested at 28 days per EN 12390-3. The delivery note must indicate the strength class, exposure class and consistency class. EHE-08 establishes additional reception control requirements in Spain.

1. Check that delivery notes indicate the correct strength class (e.g. C25/30) matching the structural design

2. Verify that test specimens were moulded during casting per EN 12390-1

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

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

5. Check consistency class (S1-S5 slump or F1-F6 flow) at delivery

- Concrete supplied with incorrect strength class

- Test specimens not taken or inadequately cured

- Water added on site reducing the strength class

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

In accordance with EN 1992-1-1 Section 4.4.1, the minimum concrete cover (cnom) depends on the exposure class, structural class and bar diameter. Typical cnom ranges from 25 mm (XC1) to 55 mm (XS3). Reinforcement must be placed in accordance with project drawings with tolerances per EN 13670 Table 11. EHE-08 and CTE DB SE supplement these requirements for structures in Spain.

1. Measure concrete cover with covermeter — must comply with the designed cnom (typically 25-55 mm)

2. Verify that bar diameters match the structural drawings

3. Check bar spacing in accordance with design — measure with tape

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

5. Ensure spacers and chairs maintain correct cover during casting

- Insufficient cover leading to corrosion risk

- Incorrect bar diameters or missing bars

- Insufficient lap lengths in critical sections

- Spacers displaced during concrete casting

In accordance with EN 13670 Section 8, formwork must be sufficiently rigid to maintain its shape during concreting. Surface finish classes range from F1 (basic) to F5 (special). Tolerances for finished elements are given in EN 13670 Table 10 — e.g. columns: plumbness +/-h/300 (min. 15 mm), beams: +/-L/500.

1. Check dimensional accuracy of finished elements per EN 13670 Table 10

2. Verify column plumbness with plumb bob or spirit level — tolerance +/-h/300

3. Inspect surface for honeycombing, blow holes or cold joints

4. Assess surface finish class against specification

5. Verify that formwork ties and embedded items are properly sealed or removed

- Honeycombing due to poor vibration or overly dry mix

- Cold joints from delayed concrete pours

- Formwork deformation under hydrostatic pressure

- Visible formwork tie holes not properly sealed

In accordance with 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 degrees C, the minimum curing is 3 days for exposure class XC1 and 7 days for XC2-XC4. Early-age thermal cracking must be controlled per EN 1992-1-1 Section 7.3. EHE-08 Article 71.6 establishes specific curing conditions for the Spanish climate.

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

2. Confirm that curing commenced immediately after finishing (within approximately 1 hour)

3. Confirm that curing duration corresponds to the exposure class and ambient temperature

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

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

- No curing — rapid surface drying causes shrinkage cracking

- Curing interrupted prematurely

- Concreting in cold weather without protection (frost damage)

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