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en-7
R
7()ASSESSING THE RESULTS DESTRUCTIVE TESTING
b) In some cases, the coating will cover only part of
the dolly face. A partial adhesion / coating failure should be
recorded if the coating covers more than 50% of the dolly face.
Partial Failure:
c) If no coating is present on the dolly this must be
recorded as a failure of the adhesive (or glue). This is normally
due to incorrect or insufficient mixing of the component parts of
the adhesive, incompatibility of the adhesive and the coating or
the dolly and / or test surface has not been properly prepared
before test - see Section 3 “Securing the Dolly” on page en-3.
Adhesive Failure:
Once pulled from the surface, examine the bottom of the dolly to
assess the results.
a) In most cases the coating will fully adhere to the
dolly and the test can be claimed as 100% valid.
Successful Test:
Cohesive Failure: When the coating fails in the body of the
coating layer leaving some coating on the surface and some
coating on the dolly face.
b)
a)
c)
Observing the test area will give additional information about the type
of failure; adhesion and cohesion between different layers of the
coating.
When testing coatings on concrete it is common for the adhesive bond
between the coating and the concrete to exceed the strength of the
concrete itself. In this case concrete will be removed from the surface
and will be seen on the coating on the dolly face.
Adhesive
Failure
Partial Coating
Failure
Concrete
Failure
Coating
Failure
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