Removing old adhesives and sealants
When preparing a subfloor to lay new flooring, the removal of old adhesives, sealants and other sticky substances has always been a challenge says Paul Igo.
‘Thick, hard adhesives can be removed with milling flails fitted to the drum of a planing machine, but this method is less effective on soft sticky materials’
TRADITIONAL methods when preparing a subfloor to lay new flooring are usually unsuccessful and have a tendency to generate surface heat, rendering the surface residue softer and stickier and displacing the adhesive rather than removing it.
Before you start, it’s useful to know the properties of the adhesive or sealant you’re dealing with. How thick is it? What is its composition; soft, hard, very sticky? Things like the environmental temperature are a key factor, as at low temperatures adhesives can be brittle and at high temperatures even tackier.
Consideration must also be made of the condition and composition of the subfloor and the surface profile that needs to be achieved in order for a new material to be applied – a second process may be required.
Thick, hard adhesives can be removed with milling flails fitted to the drum of a planing machine, but this method is less effective on soft sticky materials.
When removing tiles, scraping blades fitted to a multi-stripping machine will lift the underlying adhesives along with the surface material and any levelling compounds in one go.
However, the most effective method of dealing with adhesives, sealants and other sticky substances is by using a grinding machine fitted with PCD (polycrystalline diamond) shoes. PCDs came to the market about 10 years ago and often aren’t considered or even known about.
The benefit of PCDs is that they scrape rather than grind to efficiently ‘lift’ these problem materials. Polycrystalline Diamond is formed when diamond is sintered with a bond under high temperature and high pressure, resulting in a shoe with a longer life and high thermal stability. They generate less heat, so during the grinding operation their cutting edges remain clear.
There are plates onto which fit PCD shoes, specifically designed for 110v, 240v or 415v walk behind machines and the STG450 machine.
PCD shoes can also be fitted to all machines with plates that hold standard grinding shoes and they’re interchangeable with regular grinding shoes. In this way a floor can be cleared of adhesives using the PCDs, and then cup discs fixed to the plate ready for grinding. To save time, the PCDs can be left attached ‘in the background’.
PCD shoes are available in Double Tooth, for the removal of thick materials such as carpet backing and sealants and Triple Tooth, for the removal of thin coatings eg adhesive and for creating a ‘closer’ profile.
There are also PCD discs to fit 9in hand grinders, consisting of a cup disc onto which fit interchangeable outer rings. These are suitable for removing adhesives in confined spaces and for edgework or small areas.
There are two PCD rings available; 6-piece for the removal of thick coatings and 18-piece for the removal of thin adhesives and paint.
PCD accessories have many additional uses over-and-above adhesive removal, including the removal of other soft thick materials from latex screeds and certain asphalts.
Paul Igo is technical director at The Preparation Group
Asbestos in adhesive
Asbestos-containing materials (ACMs) can still be found in many pre - 1986 buildings. Asbestos used to be mixed with cement and particles and small percentages have been evident in flooring adhesives, used to secure a wide variety of finished floor coverings. All removal work must be undertaken by a specialist contractor holding the correct certification and their employees trained and qualified in the removal and disposal of asbestos related materials, without causing hazard to themselves, other trades and the public. All projects must be monitored and documentation outlining the works submitted to HSE.
A Case Study
The Preparation Group’s contracting division PPC, were contracted by the council to remove floor adhesive containing traces of asbestos from a block of flats in Huddersfield, that were due for demolition.
The building comprised of ten floors and equipment had to be manually lifted to each level as the lift had been disabled. The company’s Liberator 250 Grinder fitted with a PCD (Polycrystalline Diamond) Plate was used, with 9’’ Hand grinders fitted with PCD discs employed to complete the edges. Debris and fine dust particles were collected safely by an M450 industrial vacuum fitted with an ‘H’ grade filter and the contaminated material, contained in special asbestos bags.
The total area of 1,413m2 took six days to complete. The contaminated material represented a small percentage of the overall structure so by disposing of this element separately, it meant that the whole building was not classed as contaminated waste, thus reducing environmental impact and costs. The project would have taken substantially longer without PCDs.