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Getting floor coating specifications right

by Madelein
Getting floor coating specifications right

Main image: Epoxy Flooring -TAL

Floor coatings and finishing was always a relatively straightforward product application, but these days, with so many options and flooring materials available, it requires far more consideration. From the thickness of the floor and the service environment to its performance characteristics, colour and surface finish properties must be kept in mind when specifying floor coatings.

Floor coatings on well-prepared surfaces

Floor coatings such as epoxy finishes are usually used on concrete floors that endure a lot of traffic and where clean and/or hygienic conditions and an aesthetic appearance are essential.  Some common applications include food and beverage processing plants, motor vehicle showrooms, pharmaceutical laboratories, general-purpose warehouses, hospitals and large event venues.

Floor coatings must be applied over a well-prepared substrate. When the blended epoxy components chemically react, it creates a product with strength, durability and aesthetic properties that is hard to match.

Top tips when specifying coatings

As with many flooring systems, it is much easier and more cost-effective to get the initial installation right. Here are some top tips when specifying coatings:

1. Poor substrate conditions

The look and performance of a floor covering are largely dependent on what lies beneath. Pay careful attention to the correct preparation of the concrete substrate to ensure a successful and long-lasting installation.

The substrate must be integrally sound, of significant strength, as well as smooth and level. Many coatings will suffer from surface imperfections or a poor aesthetic appearance if the floor below is not perfectly smooth and level. A minimum tensile strength of 1.5 MPa is required, and specification starts with the specified concrete mix design.

2. Evaluate the surface

The surface must be suitable for the chosen floor coating. It must be clean, structurally sound and without any cracks, moisture or contamination as this will directly influence the installation. It is imperative that the surface is moisture-free or free of the effects of hydrostatic or osmotic pressure. A DPC on the subgrade below the concrete plays a vital role in preventing rising moisture/damp. The type of surface preparation will also factor in the CSP guidelines, using equivalent mechanical surface preparation to achieve e.g., CSP-3, shot blasting as per ICRI guidelines.

3. Floor preparation

It is extremely important to study the floor surface preparation required for each type of product considered. A floor is only as good as its substrate, so preparation before applying any coating is especially important.

When installing a new floor, the concrete substrate must be fully cured and have attained the moisture content stipulated by the manufacturer of the floor covering. Excessive fluctuating moisture levels in the substrate or high moisture vapour emission rates will most certainly result in installation failure, i.e. delamination from the substrate.

If there is no damp-proof membrane below a surface bed or if moisture levels do not attain 50% relative humidity (RH)/3% moisture content, a suitable moisture or vapour barrier should be installed.

4. Correct specification

The client’s needs and requirements must be evaluated in terms of on the type of business and specific installation requirements.

Cover the supply method statements with all aspects of the application, from A to Z, including the relevant system data sheets as well as a list of qualified specialised contractors for the application.

a.b.e. Construction Chemicals applied 1 000 m2 abe.®cote 337 in sea grey at the John Deere workshop in Hertzogville.

Ensure that the proposed floor coating is fit for purpose, i.e. that the system and surface finish meet the client’s required service expectation and that no shortcuts have been taken or substitutions have been made in terms of product used.

5. Application and environment

It is especially important to consider the usage of the floor before specifying a suitable epoxy system. If there is only going to be pedestrian traffic, a thin film coating will be sufficient. However, if a heavy-duty forklift and other mechanical traffic is to be used, a thicker, more durable coating or screed will need to be specified. The correct system and thickness are essential for longevity.

Weather, moisture and contamination or chemical attack are of particular importance with the application of a polyurethane coating. The climate in KwaZulu-Natal is more prone to moisture given the region’s humidity, and in winter places such as Bloemfontein can reach temperatures well below freezing. Both climatic factors influence key application considerations as they could lead to flooring failures if not correctly addressed.

Polyurethane floors applied in environments such as laboratories, kitchens or medical facilities have the additional threat of chemicals which could harm the coating. It is imperative that solutions identified for these areas are capable of withstanding various chemical based threats.

6. Maintenance plan

Epoxy Flooring -TAL

Specifying bodies also need to check that the contractor and client have included a suitable maintenance plan for the flooring system. The supply method statement for a maintenance and cleaning regime must consider the nature of the industry, e.g. hygiene requirements, the size of the area to be cleaned and use of the correct chemicals for the types of contamination that need to be cleaned.

7. Suitable applicators

A competent contractor must be appointed to do the application. Professional applicators have the correct equipment and are able to ensure that the required finish is achieved as specified. Be sure to work with an experienced installer as the installation of any floor coating needs to be effectively and carefully managed.

8. Client expectations

Clients must understand the aesthetics and performance of each product beforehand. They need to be aware of the proper cleaning and maintenance of the finished application. The applicator must apply a sample of the product as a reference and standard that must be accepted by the client before application.

Ensure that the proposed floor coating is fit for purpose and that the system and surface finish meet the client’s required service expectation.

Things that can go wrong…

An uneven or dull appearance

If the epoxy coat is applied in too hot or too cold climatic conditions, or when air flows over a curing surface, a dull and uneven appearance can be the result. Epoxy is very sensitive to temperature fluctuations and needs to be applied according to the manufacturer’s guidelines. Remove ventilation fans, switch off air-conditioning, and close doors and large windows to prevent wind from blowing across the curing surface. If dust is present during curing, it can cause small pinholes or “fisheyes” in the final surface finish.

Bubbling in floor coatings

This is the most common problem with epoxy floors. The bubbles in cured epoxy floors are generally very small (the size of the pinhead) and may appear randomly or in clusters. These bubbles can be caused by outgassing of the concrete substrate or when the product isn’t mixed correctly or is mixed too fast, leading to air entrapment. Other sources of the problem could be excessive mixing such as using a power drill at high speed or when excessive temperature causes pressure differentials that lead to trapped air that wants to equalise. Slowly circulate the mixture in a large container and be sure to use the correct ratio when the resin and hardener are mixed.

Peeling

Peeling and poor adhesion is usually the result of an inexperienced or careless applicator. It could also be poor surface preparation, contaminated materials not being removed from the surface, the incorrect mixing ratio of resin to hardener, wide temperature variations, or moisture trapped below the surface.

Craters and bubbles

Bubbles in an epoxy floor contain air or moisture, whereas a crater that leaves an indentation on the surface is generally caused by dirt or contamination while the epoxy is still curing.

Floors, as simple as they might seem, can be complex and calling experts in early on not only saves headaches later, but also significant costs on a failed installation.

Full thanks and acknowledgement are given to www.abe.co.za, www.mapei.co.za, https://zaf.sika.com and www.tal.co.za for the information contained in this editorial.

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