Dealing with newly laid concrete
10 September 2021
Rising moisture is a resin floor system’s worst enemy. If moisture comes into contact full bond strength may not be achieved. This in turn could result in blistering, partial delamination, or complete failure of the full resin system, cautions PSC Flooring.
CONCRETE SHOULD be solid enough to walk on, without leaving footprints, after anything from 24 to 48 hours. By seven days, the concrete should be cured to at least 70% of its full strength and you should be able to drive on it without damaging it, but it is not until 28 days that concrete manufacturers consider concrete to be fully hardened. Factors such as moisture, temperature when laid and mix design can all affect the strength and hardening time.
When laying coatings or screeds onto a newly laid concrete slab it is imperative that moisture readings are taken at multiple points over the floor to assess the moisture present. Every slab of concrete has moisture and will always have moisture, even when it is considered dry and fully cured. Hydrostatic pressure is the pressure exerted by fluids at rest. As a flooring contractor, a Protimter MMS2 instrument is an essential instrument used to detect the Hydrostatic pressure /moisture content of existing floors. The search mode detects sub-surface moisture utilising pinless radio frequency finds moisture up to 3/4 in (19mm) below the surface. Moisture readings: 0 to 169 – no risk of rising moisture; 170 to 199 – at risk of rising moisture; 200+ – classified as wet.
If a reading is over 170 we would always recommend applying a DPM (Damp Proof Membrane) also known as epoxy resin primer.
PSC Flooring was recently contacted by Wye Valley Group. They are a busy waste recycling centre, based on Rotherwas Industrial Estate, Hereford, to look at refurbishing their floor surface in the workshop area, totalling 788 sq m. The customer was looking for a hard-wearing, functional floor that could withstand the rigours of their business yet would be easy to keep clean. PSC recommended a two-coat epoxy resin flooring system.
When moisture readings were taken at multiple points over the floor it was showing readings at between 230 to 240. The floor was given a coat of Damp Proof Membrane epoxy resin primer. Once this was completely dry, the two-coat Resdev Pumatect high build, epoxy resin flooring system was laid in the client chosen light grey.
In preparation for laying the two-coat epoxy resin flooring system, the main floor surface was thoroughly cleaned and prepared. This was with a light shot blast and the edges using a handheld 110v diamond grinder. The entire area was then vacuumed clean to remove all residues and dust. This was before any repairs were made to any damaged localised concrete, expansion joints, holes, and cracks.
Finally, to enhance health and safety, a 200mm wide demarcation line was installed. This was around two pit areas and Rolling Roads in Resdev Pumatect high build, epoxy resin flooring, safety yellow.
Wye Valley Group construction manager Phil Pilcher-Morris, says: “The high build, epoxy resin flooring system laid by the team at PSC Flooring has completely transformed the space, brightening the area.”
The job was completed in 4 days, on time and on budget.
For more information, visit www.pscflooring.co.uk