COATINGS on CONCRETE SLABS and OTHER CEMENTITIOUS SUBSTRATES

This is a new section to our website which is currently under development.

This section will address some of the issues relating to coatings applied to concrete slabs and other cementitious substrates along with the testing of these coatings for adhesion, thickness, and moisture emissions reduction.

Other issues that will be addressed are pre- and post-installation testing of concrete for chemical, mineral, or other contaminants that effect the bonding and/or performance of coatings. These tests can be helpful in reducing the potential for coating failures or in the forensic analysis of concrete coating failures.

While this section is being developed, please contact us with any inquiries to our consulting, testing and inspections services relating to concrete coatings.

Coating Thickness

The dry film thickness of a coating can affect many of its properties such as hardness, flexibility, adhesion, or permeability. Most manufacturers of high-performance or protective coatings have minimum and/or maximum dry film thickness tolerance specifications required for their product to be functional in its intended purpose. These requirements can be for each coat, the total thickness of multiple coats, or both.

In the the application of most topically applied concrete slab moisture remediation or mitigation systems, the coating thickness has a direct impact on the permeability of the product. Some concrete moisture control products will specify applications of the same product at different thickness based on the maximum anticipated moisture emission level of the concrete slab. Many of these products will provide a warrantee in part based on the application meeting the required minimum coating thickness requirement.

Testing Coatings Thickness

The Bell CS Group utilizes three methods for determining the dry film thickness of coatings on cementitious surfaces which follow ASTM and SSPC standards. Two methods can be performed on-site utilizing an ultrasonic gauge or a Tooke gauge to determine a coating thickness. A core can also be taken then through petrographic analysis under a lab microscope, the coating thickness can be determined.

Adhesion of Coatings

Following applications of a coatings on a concrete slabs and other substrates it is useful to determine the bond/adhesion strength of the coating to the substrate. The Bell CS Group performs adhesion testing utilizing a digital pull-off apparatus which determines the tensile strength of the coating. This is performed by attaching a dolly to the coating which is cored to isolate the coating under the dolly from the adjacent coating. The pull-off testing instrument will then measure the tensile force that is required to either debond the coating from the substrate or cause a failure of the concrete substrate. By utilizing electronic technology we are able to datalog the pull off pressure, rate of pull, and test duration/timing. 

To be added soon:

• Other testing of coatings on cementitious substrates

• Coatings for concrete moisture and alkalinity remediation

• Wear/protective coatings on cementitious substrates

Some of our coatings tests include:

Bond Testing of Epoxies, Paints, Polymers, Urethanes, and other Coatings on Cementitious Substrates

ASTM D4541–02 Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers

ASTM D7234-05 Standard Test Method for Pull-Off Adhesion Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers

Thickness Testing of Epoxies, Paints, Polymers, Urethanes, and other Coatings on Cementitious Substrates

ASTM D4138-07a Practices for Measurement of Dry Film Thickness of Protective Coating Systems by Destructive, Cross-Sectioning Means

ASTM D6132-04 Standard Test Method for Nondestructive Measurement of Dry Film Thickness of Applied Organic Coatings Using an Ultrasonic Gage