Concrete Coatings Articles

Cracking the Code on Concrete Repair

Photos courtesy of Rock-Tred

Failing to spot and document mistakes in concrete before applying a coating system may result in losses for your coating contracting company. It is not enough to have 20 years of experience with coatings. If you don’t understand the concrete you are applying coatings on, experience won’t help.

New Concrete

There are many benefits to working on a new construction site. The history of the concrete pour has most likely been documented. Weather reports, batch tickets, and other concrete testing results are usually available. Specifications, drawings, and the concrete contractor or general contractor are usually available as references.

Asking questions, keeping good notes, taking pictures, and performing tests are all critical to both the success of the flooring project and, ultimately, your protection. Some critical information includes:

• The specification section(s) covering the mix design, slab thickness, subbase, compaction, steel reinforcement, and moisture barrier/retarder for the specified area to be coated.

• The specification covering the flooring system to be installed.

• The soil report for the worksite.

• A copy of the submittal for any required moisture barrier or retarder.

• Identification of contraction, construction, expansions, joints, etc.

• Verification that the contraction joint plan was followed.

• Repair requirements for cracks (don’t assume this is your work).

• Noted time lapse between the concrete pour and troweling or cutting the joints.

• Depth measurements of the joints.

• Sounding at the side of joints, re-entrant corners, and slab ends to detect areas where the slab is not in contact with the subbase.

• Approved flooring material submittals and detailed installation instructions.

Old Concrete

Obtaining design information on older concrete slabs can be difficult for the simple reason that the data may have been lost over time. When most or all of the contract documents are missing, visual inspection and testing become critical.

You should consider taking these additional steps:

• Core drilling over a crack and joint to ascertain the type of crack(s) exhibited, to learn the thickness of the slab, to see if a vapor barrier/retarder was installed, and to see the subbase and construction practice employed.

• Sending the cores out for testing if contaminants are known or suspected or if the concrete feels punky or chalky. The joints are often the place where contaminants first show themselves when a floor is finished.

• Random testing with a rebound hammer to spot check the compressive strength of the existing concrete. This will also help detect areas where the concrete is not in contact with the subbase, as a hollow sound with low compressive numbers will result.

In all cases, take pictures and create detailed drawings of the joints and cracks that are visible, as well as those areas where a hollow sound was detected. If this step is not completed, the coating contractor will probably take the blame for any new crack that appears, for not having properly addressed the cracks prior to over-coating the floor. This process is time consuming, but it will help ensure protection against repairing new cracks for free.

Follow the Contractual Chain

Once the information is gathered and thoroughly examined, you should present your findings in a clear, concise document to the proper authority in the contractual chain. This document should contain areas of concern, such as where the specification is silent or fails to address the issues that you discovered while gathering the information.

Concerns relating to joint and crack repair and any defective areas that will negatively affect the performance of the flooring system and/or warranty should also be included in this document. For example, if the concrete floor was specified to receive two coats of a water-borne epoxy sealer with a total system of 3–5 mils (76.2–127.0 microns) dry film thickness (DFT) and the majority of the floor is covered with crazing cracks, it would be imperative for you to express that the specified system will most likely not hide the crazing cracks.

If asked by the owner or owner’s representative what should be done to correct the issue(s) at hand, you should speak from expertise only! Recommending a solution that fails to resolve the matter or exacerbates the issue may result in liability and losses both financially and to your credibility. If the specification is in contradiction to the approved manufacturer’s repair instructions, you should involve the manufacturer and always make sure to submit a written RFI (Request for Information) through the proper contractual channels. Lastly, do not start work until you have received a written response to your RFI.

When You Get the Call

If you have been in the business long enough, you will eventually get a call stating that your flooring has cracked and needs to be repaired immediately. Before you react, it is important you do the following:

• Listen to the complaint in detail and don’t get defensive!

• Ask preliminary questions and write down the answers.

• Schedule a site visit and bring the flooring manufacturer representative.

• Take your file with you to the jobsite and compare your notes with the location of the failed area(s).

• Examine the crack(s). Carefully cut across the crack(s) with a thin, sharp blade to see if the crack originates in the concrete. If it does, see if the crack contains patching material and determine whether it was repaired previously by your crew or is new. (See photo).

• Consult an expert if you are not sure what caused the crack.

Once you are convinced as to why the crack occurred, take the time to answer true or false to the following questions:

1. The cause of the crack was completely outside of my control.

2. I followed the specification and manufacturer’s directions completely.

3. The workmanship was performed correctly.

4. The material was stored, mixed, and used per the manufacturer’s guidelines.

5. I did not write the specification.

6. I did not design, place, cure, or dry the concrete slab.

7. There was nothing I could do to prevent the crack.

If you answered true to all of the above questions, then you most likely are not responsible for the repair. If you answered false to one or more of the above, then you may have some degree of responsibility.

Crack the Code

Cracks remain a challenge to the resinous flooring industry and can steal profits when they are not addressed and documented properly. The quality of the concrete is most always outside of the coating contractor’s control. Historically, coating contractors have been blamed unfairly when new cracks develop after the coating has been installed.

You and your crew have a responsibility to know your profession and to perform your work per established best practices, specifications, and manufacturer’s installation guides. But you don’t design the concrete mix, place the concrete, control the layout for saw cutting or cut the contraction joints, control the water/cement ratio, control the curing mechanism or quality of curing, or control the drying process. These facts must be communicated and documented or it is likely that you will be held responsible for the cracks that appear even when they are not due to your defective labor or material.

For far too long coatings contractors have been making free repairs for cracked concrete over which they had no control. By taking the time to understand, document, and communicate the condition of cracks to the customer before coatings are installed, the resinous flooring contractor will not only keep more of his profits but will do a great service to the resinous flooring industry.

This is the second article from Chris O’Brien regarding concrete repair and coatings. To read the first article, called “The Very Beginning: Understanding the Concrete You’re Coating,” click here.

About the Author:

Chris O’Brien is the founder of Prime Coat Coating Systems and currently acts as Vice President of Flooring Systems at Rock-Tred, an ICP-owned company. For more information, contact: Chris O’Brien, 

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