Underneath every beautiful, smooth and sparkling floor finish is the substrate – and whilst the completed surface you walk on is a work of art, the concrete foundation underneath might be a problematic, frustrating and challenging concern to the developer for a variety of reasons.
To help you smooth over the substrate stresses, we’ve compiled Flowcrete’s top tips for taming this troublesome layer of the floor build-up.
1) High Moisture Content
Substrates with high moisture content need to be specially treated, as moisture vapour that gets trapped underneath the floor’s surface will cause unsightly blistering. This was a particular concern at the new car showroom for BMW Brilliance’s ZINORO 1E in Beijing, where the moisture content of the newly laid concrete threatened to impair the high quality, luxurious finish of the floor.
To fix this a damp proof membrane was applied to create a water-free moisture tolerant primer between the concrete and the decorative surface layer that would prevent moisture entrapment from ruining the floor.
2) Thermal Coefficient of Expansion
The concrete substrate will expand and contract when subjected to temperature changes. By knowing the thermal coefficient of expansion you can predict the extent to which heat changes will affect the substrate and tailor the building’s design accordingly.
If a facility is likely to undergo temperature swings over time then a cementitious polyurethane resin floor will help to prevent the substrate’s movement from cracking the floor finish better than an epoxy resin. This is because cementitious polyurethane exhibits a thermal coefficient of expansion similar to concrete so it will expand, contract and move with the substrate.
Cementitious polyurethane floors are also better than epoxy systems at dealing with the thermal shock caused by very fast temperature changes (such as intensive hot water washes).
3) Take Care of your Screed
It’s the screed that has to bind the floor finish to the substrate, which makes this a vital component to get right. If applying a bonded screed then make sure that the concrete slabs are properly prepared by shot blasting off the weaker top surface layer as it is better for the screed to bond with the harder aggregates underneath.
4) Long-term Protection
The needs of the substrate don’t stop after the construction has finished, as the day-to-day life of the building could damage it if it is not properly protected. Highly resistant polyurethane coatings can be used to create a protective barrier between contaminants and the substrate, avoiding early corrosion and damage to the concrete foundations.
When refurbishing the floor it’s important to look out for any cracks or contamination brought about by chemical exposure, as these will need to be fixed before installing the new floor. Deep cracks can be reinforced, filled in with a flexible resin or over-bonded with an additional elastic membrane.