💧 Concrete water permeability
Testing depth of water penetration under pressure in hardened concrete. Key durability parameter of concrete structures exposed to water.
Overview
Concrete water permeability is one of the most important durability parameters of reinforced concrete structures exposed to water — foundations, tanks, tunnels, bridges and hydraulic structures. Standard PN-EN 12390-8 describes a standard method for assessing water penetration depth under pressure, which is an indicator of concrete pore structure tightness.
Water penetration depth depends on w/c ratio (water/cement), cement type, presence of additives (fly ash, silica fume), degree of compaction, curing and concrete age. Standard PN-EN 206 defines exposure classes (XC, XD, XS, XF, XA), many of which require water permeability testing as a concrete acceptance criterion.
In Polish construction practice, waterproofness grades W2, W4, W6, W8, W10, W12 are used (according to former PN-88/B-06250), corresponding to maximum water pressure at which no seepage is observed. The European standard PN-EN 12390-8 uses penetration depth in mm at constant pressure 500 kPa for 72 h.
The test is performed in concrete plant laboratories, on construction sites (ready-mix concrete acceptance) and in research laboratories. It is mandatory for concretes of exposure classes XD, XS and XA according to PN-EN 206.
Method principle
Concrete sample (cube, cylinder or cuboid with side/diameter ≥150 mm) is placed in pressure device so that water under pressure (500±50) kPa acts on selected surface (usually molded surface) for (72±2) h. After test completion, sample is broken (split) perpendicular to surface on which water acted. On the fracture surface, a dark zone saturated with water is visible — maximum water penetration depth is measured in mm. The smaller the depth, the more waterproof the concrete.
Applications
- Quality control of ready-mix concrete on site (classes XD, XS, XA)
- Testing of concretes for hydraulic structures (dams, locks, tanks)
- Durability assessment of foundation concretes in aggressive soils
- Design of waterproof concrete mix (w/c selection, additives)
- Quality control of concrete precast elements (pipes, manholes)
- Comparative tests of sealing admixtures effect
- Construction expert opinions — assessment of existing structures condition
Key parameters
| Parameter | Value |
|---|---|
| Water pressure | (500 ± 50) kPa (0.5 MPa) |
| Test duration | (72 ± 2) h (3 days) |
| Min. sample dimension | ≥150 mm (side or diameter) |
| Sample age | ≥28 days |
| Result | Maximum penetration depth [mm] |
| Criterion (typical) | <50 mm — waterproof concrete; <20 mm — high waterproofness |
Standard
- Standard number
- PN-EN 12390-8:2019
- Title (PL)
- Badania betonu — Część 8: Głębokość penetracji wody pod ciśnieniem
- Title (EN)
- Testing hardened concrete — Part 8: Depth of penetration of water under pressure
Step-by-step procedure
1. Sample preparation
Cubic samples 150×150×150 mm or cylinders ∅150 mm after min. 28 days curing. Mark test surface (molded).
2. Surface drying
Dry test surface in air. Optionally seal side surfaces (paraffin, silicone) — prevent side leakage.
3. Sample mounting in apparatus
Place sample in pressure holder. Tighten clamping flanges with rubber gaskets. Check connection tightness.
4. Water pressure application
Turn on water supply. Set pressure (500±50) kPa. Check pressure stability in first 30 minutes.
5. Pressure maintenance
Maintain 500 kPa pressure for 72±2 h. Monitor pressure at least 2× daily. Correct any deviations.
6. Sample dismounting
After 72 h release pressure. Remove sample from apparatus. Dry external surface.
7. Sample splitting
Split sample perpendicular to surface on which water acted (splitting press or wedge). Immediately examine fracture.
8. Penetration depth measurement
On fracture mark boundary of dark zone (water-saturated). Measure maximum penetration depth with caliper to accuracy of 1 mm.
9. Results documentation
Note: maximum depth [mm], penetration front description, fracture photo. Compare with design requirements.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Concrete waterproofness testing apparatus | Multiserw-Morek, Controls 55-C0225, Matest C390 | 25 000–80 000 PLN |
| Air compressor / pressure pump | Piston compressor 10 bar, pressure regulator | 3 000–10 000 PLN |
| Press for splitting samples | Controls 50-C0220, Matest C070, Multiserw-Morek | 20 000–60 000 PLN |
| Caliper / steel ruler | Mitutoyo 500-196, accuracy 0.1 mm | 200–800 PLN |
| Rubber gaskets / clamping flanges | Sets for sealing samples in pressure apparatus | 500–2 000 PLN/set |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Tap water (test medium) | 7732-18-5 | Drinking water, temperature 20±5°C, applied under pressure to sample |
| Sealing material | — | Silicone, paraffin wax or epoxy resin for sealing side surfaces of sample (optional) |
Health and safety (OHS)
- Water pressure 500 kPa — risk of sudden leak! Safety goggles mandatory
- Splitting press — danger of crushing, protective shield and operator training
- Heavy concrete samples (>8 kg) — lifting ergonomics, work gloves
- Wet floor in laboratory — non-slip footwear