The following are some of the more common tests that are to be performed or offered to the customer by the
applicator prior to the preparation of the slab for any given project. These tests require a sample, (drilled core), be taken
and sent to a testing laboratory for analysis. These are usually 3" in diameter by 2", (called a 3X2), or through
the entire slab depending on what is being checked. A 3" X 2" core is the usual size required unless the lab requests
a deeper core for further testing. As far as cost is concerned, the cost of performing these tests of 3 or 4 core samples
is very small compared to all the possible costs invoved in a coating failure down the road. Usually the facility owner will
pay for these tests to be performed but, if not, this is relatively inexpensive insurance policy that will go a long way to
assuring a more successful job.
This test checks the sample for organic contaminates in the concrete such as hydrocarbons, oils, fats,
etc. This is a test is recommended for all coatings applications and is inexpensive.
This test is primarily used to check the concrete cap for silicates from curing or hardening agents applied
to the slab after it was poured. If these silicates are not identified and a coating is applied, the silicates act as
a bond breaker and the coating will delaminate from the substrate. This is a very inexpensive but critical test, and should
be offered in all projects where it is not known weather the concrete contractor used an after-pour treatment.
X-ray Diffraction (XRD)
This test is to determine the inorganic makeup of the concrete.The results of this
test are used to determine any deleterious constituents in the concrete and will give the applicator warning of potential
problems. He can then plan a strategy of alternative coatings or restoration procedures to remedy the problem. This test
is also recommended for all coating projects.
Energy Dispersive X-Ray (EDXA)
Determines mineralogical composition of the concrete cap and usually used in conjunction
wiht the XRD.
Thin Section Petrographic (ASR)
This test is usually performed on older concrete slabs to check for ASR (Alkali
Silica Reaction) activity. ASR is not common to the entire USA but seems to be found in certain areas only, primarily the
aggregate used in a particular pour of concrete. The culprits are fossilized aggregates which are unique to these areas.
When it does occur it is a very destructive process that will deteriorate both the concrete and any coating system applied
to it. How ever there are physical signs of this activity that manifest on the surface of a given slab undergoing active
ASR. The applicator should become knowledgeable enough on this subject to be able to at least recognize some of these signs
and then recommend that testing be done to determine if ASR is present. This test is not a commonly performed test,
but ASR is being found in more and more slabs, (in the effected regions), as professionals become more aware of the symptoms
and causes of ASR. This is usually a more expensive and thorough test procedure and not usually recommended for every project.