The Many Issues That Sub-Standard Concrete Causes


Not all concrete is the same, and there are several factors which can impact our work as epoxy flooring installers.

Concrete has a base level of ingredients.

  • The first is cement. On its own, cement does not constitute concrete or harden without other components.
  • Another ingredient is sand. River sand is a common form as it has been washed.
  • Various aggregates also comprise the concrete mix and helps bind the properties. The size and shape of the aggregate impacts the pliability of the concrete along with durability and strength.

When the concrete leaves the batch plant, it is regulated in terms of its components. When it arrives on site, things can change.

There are accelerants, retarders and additives that can compromise the overall structural integrity of the set concrete finish. An example of this can be adding too much water. This makes the concrete very easy to work with, but can raise the ‘fines’ to the top of the set product, making it very weak.

In terms of coating concrete that is not to code, there can be many issues.

Case Study – 2 Side by Side Garages with Very Different Concrete Floors

In 2017, we were engaged by a builder to install epoxy flooring to two double garages, located side by side, for the same client.  This was a ‘last minute’ project, where we were helping the builder to meet their deadline with handover.

One garage had pre-existing concrete floor, and the other had a brand new concrete floor. The preparation through grinding was very different in terms of equipment and diamonds we needed to use on each floor.

After the grinding was done, we advised that the newly poured slab had issues and would add days and cost to the job. The builder did not have any time, and so we were instructed to complete both garages together.

Months later following completion, the owner called us advising that the work on the newer slab had failed, and that he would engage us directly to fix it.

We had a concrete expert assess the concrete. Along with being structurally weak, he advised that, with so much water added, the top 5-7mm was soft and would need considerable work to rectify. Along with this, it was not to standard.

Due to the poor state of the concrete, it took us five days to get the quality of the concrete up to code, and involved the application of several priming coats of products and additional trowelling.

The Many Issues That Sub-Standard Concrete Causes

The top ‘crust’ of concrete is called laitance. It is very difficult to determine the quality of what is underneath the crust, without the use of expensive professional equipment, like a Schmidt Hammer, which determines the compressive strength of the concrete along with other useful information.

The Many Issues That Sub-Standard Concrete Causes

This aside, grinding 5-7mm down is not practical and as such, we needed a lot of additional resin and time to complete.

Once we completed the area, we advised the owner that a 7-day curing period was essential, and that we would stay in contact to determine adhesion and stability. 3 months later, I checked in with him and all was fine.

The Many Issues That Sub-Standard Concrete Causes

Cutting corners costs more in the long run

As you can imagine, in a situation like this, it’s only natural that the owner would be suspicious of an epoxy flooring contractor who delivered a finish that failed, and the work had to be redone.

Lucky for us, we had the original garage with the stable concrete floor, as a reference point which gave the owner full confidence in our skills and quality.  As a result of this, along with independent testing, we built a solid relationship directly with the owner, and he was very happy with the work we put into rectifying and producing a high-quality finish that matched the first garage.

We were glad to be of help but something like this highlights the importance of proper consultation, the right tools, guidance and timeframe. The process cannot be rushed or bypassed if wanting a quality long lasting finish.

Get it done right the first time

As demonstrated by this case study, a quality concrete slab is required as a base for a quality epoxy finish.  We trust, recommend and have had first-hand experience using  TDH Concrete Services for concreting work in the Brisbane region.

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About Euan Bennett

A self-confessed epoxy flooring nerd and dog lover, my great team and I just love transforming an ordinary floor into a thing of beauty with a carefully applied epoxy finish.