What does delamination actually mean?

Delamination is a loss of bond within a layered assembly. On a resin floor, separation may be at the concrete–primer interface, within weak concrete or repair mortar, between primer and body coat, or between finish layers. A visible peeling edge alone cannot prove which party or material caused the problem. Water beneath a blister, concrete dust on the underside and a glossy intact lower film each suggest different lines of enquiry.

Likely causes to test, not assume

Substrate preparation and strength

Mechanical preparation must remove laitance, coatings, oil and weak material and produce the profile required by the selected system. A polished slab or dust left after grinding can prevent wetting and mechanical key. Pull-off testing can identify whether fracture occurs in sound concrete, a repair layer or the interface; interpret results against the project specification and failure mode, not a single universal threshold.

Moisture and vapour movement

A slab’s age is not a moisture reading. Investigate leaks, absent or failed vapour barriers, external water, washing and the relative humidity of the concrete where relevant. Surface meters can screen an area but should not be treated as a substitute for the test method and limits in the system documents. Entrapped moisture and osmotic pressure can also create blisters that later lose adhesion.

Timing, temperature and chemical contamination

A missed recoat window, condensation at dew point, amine blush on some epoxy systems, oil or silicone contamination, wrong mix ratio, insufficient mixing, incompatible layers and early traffic can each affect adhesion. Compare daily site records, batch numbers, ambient and substrate temperatures, humidity, pot life and cure time with the current TDS.

A defensible investigation sequence

1. Map and photograph the failure, adjacent sound areas, joints, drains and moisture sources. Record occupancy, cleaning chemistry and operating changes.
2. Mark the fracture plane on representative samples. Inspect underside deposits and whether failures concentrate at edges, drains, traffic routes or repaired patches.
3. Review specified layer schedule, batch and mix records, surface preparation, substrate tests, environmental readings and time between coats.
4. Arrange project-appropriate adhesion and moisture testing on both affected and apparently sound areas. ASTM D7234 describes pull-off testing of coatings on concrete and failure-plane reporting.
5. Agree an extent of removal based on sound boundaries and repeatable testing. Establish a trial area, record preparation and acceptance criteria before full repair.

Suspected structural concrete damage, extensive moisture ingress or hazardous exposure warrants a suitably qualified specialist’s assessment before reinstatement.

Repair and prevention

Remove loose film and weak substrate back to sound, dry material. Correct the water source or contamination, repair defects and prepare the surface to the approved profile. A compatible primer or moisture mitigation layer must be selected against measured conditions, not used as a generic cure. Observe mixing, recoat and cure windows, then document inspections and handover. If multiple layers have failed, isolated cosmetic patching may leave the same mechanism active beyond the visible edge.

For a new project, specify substrate acceptance, moisture testing, trial areas where warranted, surface profile, layer compatibility and hold points in advance. See our moisture assessment and concrete preparation guides.

Common questions

Technical references and further reading

• ACI 515.3R-20: Assessment and Surface Preparation for Concrete Protection Systems
• Sika: Concrete surface preparation for resin flooring
• Sherwin-Williams: Preventing premature coating failure
• Additional technical reference

These references describe general mechanisms. ALKA’s current product TDS, approved build and the project’s measured conditions govern the actual repair.