Overview
ISO 1920-11:2013 - "Testing of concrete - Part 11: Determination of the chloride resistance of concrete, unidirectional diffusion" specifies a laboratory method to evaluate the chloride resistance of hardened concrete by measuring unidirectional, non‑steady‑state chloride ingress. The method produces a chloride penetration profile and derives parameters such as the initial chloride content (Ci), the surface chloride content (Cs) and the non‑steady‑state diffusion coefficient (Dnss) for comparative ranking of concrete mixes.
Key features:
- Standard reference exposure: 3 % NaCl solution, typically 90 days immersion after specimen conditioning.
- Minimum specimen age and test duration considerations (standard curing 28 days; note/test can require a minimum total period of ~119 days).
- Vacuum saturation, surface sealing on all but one face, controlled exposure and profile grinding to obtain chloride concentration vs. depth.
Key technical topics and requirements
- Specimen preparation and conditioning: Cast cylinders/cubes per ISO 1920‑3; specimens are split into a profile specimen and an initial chloride sub‑specimen.
- Exposure method options: full immersion, ponding or inverted immersion of the uncoated face; solution composition and exposure period must be recorded.
- Vacuum saturation: profile specimens are usually vacuum saturated with demineralized water before exposure (optional but must be reported if omitted).
- Chloride analysis: acid‑soluble chloride content measured layer by layer after grinding at least eight successive layers from the exposed surface.
- Data analysis: nonlinear regression (least squares) on the chloride profile to determine Cs and Dnss; test precision indicates high variability (≈15 % CV for Dnss), so three specimens are normally tested and results reported individually.
- Reagents & apparatus: analytical‑grade chemicals, water‑cooled diamond saw, temperature‑controlled chamber (20 ± 2 °C), exposure containers with defined solution volume-to-surface ratio.
- Annexes: provide guidance on diffusion coefficients, core specimens, immersion methods for large specimens, vacuum saturation procedures and grinding intervals.
Practical applications and users
ISO 1920-11 is used to:
- Rank and compare concrete mixes for resistance to chloride ingress (important for durability design).
- Support material selection for marine structures, bridges, parking structures, and other chloride‑exposed infrastructure.
- Provide input data for service life modelling (chloride diffusion parameters).
Primary users:
- Concrete technologists, materials laboratories, R&D teams, precast manufacturers, specifiers, infrastructure owners, and durability consultants.
Related standards
- ISO 1920 series - Testing of concrete (Parts 1–12)
- ISO 1920‑3 - Making and curing test specimens
- ISO 1920‑6 - Sampling, preparing and testing of concrete cores
(Note: steady‑state diffusion tests are outside the scope of this part; alternative exposure concentrations or artificial seawater may be used but must be reported.)