Chloride Migration (DRCM) and 120-Year Durability in UHPC

Why chloride migration matters

For bridge decks, marine structures, and de-icing salt environments, compressive strength alone does not define service life. Specifiers need evidence that chloride ingress is controlled over decades — often targeting 120-year design life in aggressive exposure classes.

The non-steady-state migration coefficient (D_RCM) per NT BUILD 492 (and related national adaptations) is a common screening parameter for UHPC and high-performance concretes in XS exposure classes.

Typical UHPC performance targets

Structural UHPC with ultra-low water-binder ratio (W/B ≤ 0.20), high silica fume content, and dense particle packing can achieve D_RCM values an order of magnitude lower than conventional C50/60 concretes when properly proportioned and cured.

Project-specific acceptance criteria should reference:

• Exposure class (e.g. fib MC2010 / EN 206 XS3)
• Test method (NT BUILD 492, GB/T 50082 adaptations)
• Age at testing (often 28 or 56 days, per specification)

From lab screening to project approval

A durable UHPC program typically includes:

1. Mix design with verified W/B, fiber system, and curing protocol
2. DRCM / RCPT screening at lab scale
3. Carbonation, freeze-thaw, and sulfate tests where exposure demands
4. Industrial trial batches with QC documentation before OEM release

Durability results should be reported alongside f_cm,28 and post-cracking behavior — not as a standalone marketing claim.

Specification language for international partners

When writing tender documents, tie durability requirements to testable limits (maximum D_RCM, minimum cover, curing requirements) and require batch records from OEM partners.

For project-specific durability assessment or OEM QA support, see our services page or contact us. Related bridge and facade applications are in our project portfolio.