Floor Substrate Preparation

Substrate Preparation for Resin Flooring

An Overview of Substrate Preparation for Resin Flooring

Generally floor cleaning and preparation, prior to applying any Resin Flooring, is a matter of common sense – provided that you understand and consider the resin flooring materials, the concrete or screed substrate and its surface condition, together with your resin floor system’s performance and durability requirements.

This is actually almost exactly the same question as “Should I rub down and prepare my enamelled steel radiators, wooden doors / window frames (etc.) before I paint them”– except that you do not normally also walk or drive over these surfaces, and so their paint bonding and performance requirements are always much less than those of a floor - And yet no sensible person would consider not cleaning and preparing all of these surfaces before painting them.

Additionally as a further example, plastered or rendered walls, do not normally need any surface preparation, other than the full drying out and cleaning of the surface, before painting them with water based emulsion paints – This is because they are porous and at least some of the paint penetrates (provided they have been given time to dry out sufficiently). But most importantly again, we do not walk or drive cars, forklifts or other vehicles on these surfaces either!

The surface preparation requirements can be considered in the same logical way with concrete floors – If you are going to expose your resin floor to heavy and frequent foot traffic, or any kind of wheeled / vehicular traffic, then it makes sense to carry out some form of surface cleaning and substrate preparation to ensure it can be successfully applied and will remain securely bonded to the concrete substrate. – So the level and effort required for the substrate preparation is directly related to the existing condition and cleanliness, plus the type of resin floor to be installed and you resin floor’s intended future traffic and exposure or loading. i.e. A simple water based (water dispersed) epoxy resin floor paint being used just to brighten up and dustproof a little used domestic storage area, would not normally need much more cleaning and preparation than simply making sure the area was clean and dry, and removing any visible dirt or dust.

It would not deserve or demand the same level of consideration and effort as should be given for the use of a high performance, solvent free epoxy resin, PU resin, Polyurea or Vinyl ester resin floor system (Resin Floor Classification Types 4, 5, 6 or 7and 8), that is to be used in an area to be subjected to frequent fork lift trucking and chemical liquid spillages.

In this situation, the resin flooring system should have a full evaluation of the best and most suitable cleaning and / or preparation requirements. This is common sense, otherwise its’ bond to the concrete surface would not be durable as it could not tolerate or withstand any of this type of severe exposure.

Surface Preparation Rules for Resin Flooring:

There are a few simple rules that should therefore always be followed for successful Resin flooring:-

- Resin Flooring should generally only be applied to dry concrete or cement screed surfaces (unless the product / system is specifically designed for damp substrates).
- Any dirt or loose / friable materials must be removed.
- Any existing old, de-bonded, loose or flaking floor paint or deteriorated resin flooring materials must be removed before any new type of resin flooring can be applied. However firmly adhering, sound existing floor paints can be over-coated, but only with an appropriate resin floor paint product (not a thicker layer resin system or screed which all require a strong mechanical bond directly to the substrate) – Which type of resin floor system is acceptable for this over-coating depends on the type of the existing floor paint and your future performance requirements i.e.

• Existing sound and fully bonded single pack resin paints should only be over-coated with a similar single-pack floor paint material, and only for light and domestic applications.
• Existing sound and fully bonded moisture cured polyurethane resin floors can be over-coated with epoxy-resin based materials, provided the surface is uniformly finely abraded to provide a mechanical key (i.e. with suitable abrasive pads etc.)
• Existing sound and fully bonded, solvent based epoxy resin, or solvent free epoxy resin floors, can be over-coated with any of our epoxy resin based floors, provided the surface is uniformly finely abraded to provide a mechanical key (i.e. with suitable abrasive pads etc.)
• Existing sound and fully bonded, water based epoxy resin floors can be directly over-coated with any of our water based epoxy floors, the surface only needs to be thoroughly cleaned, and there is no need to abrade the surface with these materials.

- On new fully hardened concrete and cement screed surfaces any curing agent residues or any cement laitance must always be removed (see New Concrete and Cement Screed Floors below)

- The concrete or cement screed substrates must be sufficiently thick, sound and strong enough to meet your service requirements. As an example - industrial floors in factories, warehouses and commercial facilities are recommended to have a compressive strength of at least 25Mpa and a pull-off / cohesive strength of at least 1.5Mpa – This is not normally a problem for new floors – See New Concrete and Screed Floors section below. But the strength and condition of existing concrete floors should always be checked – See ‘Floor Substrate Testing’ below.

- By following these relatively few and simple rules you can be assured of a successful resin flooring job.

More information and details on exactly how to do this are given in each of the sections below – But if you have any concerns or additional questions, please call any of our offices and one of our Resin Flooring specialists will assist you.

Surface Preparation of New Concrete and Cement Screed Floors

For most domestic and light duty floor painting projects, the three most important criteria are ensuring that the concrete or cement screed is fully cured, hard and dry, plus ensuring that the surface is finished correctly.

This also means that generally a concrete floor slab must always be a minimum of 28 days old before any vapour-tight resin flooring can be applied – And this is only provided they are indoors, protected and not externally exposed to rainfall, etc., as with car park decks for example.

For larger areas and thicker concrete floor slabs, as 150 to >200mm thick concrete slabs are used for most medium to heavy duty service requirements, the concrete can actually take much longer to dry out – for example a 200mm thick new ground floor concrete slab laid over a DPM without any additional heating or ventilation, can take up to a full year to dry out to a moisture content of 4% by volume – which is the maximum recommended for any application of any vapour-tight resin floor.

Fortunately there are resin flooring systems that are designed to be suitable for earlier application, or even application onto continually damp concrete floor surfaces i.e. for maintenance and upgrading in the food industry. These include water dispersed polyurethane / cement screeds (such as Sika Purcem or BASF Ucrete), plus our range of water dispersed epoxy resin flooring systems. This is because they are not only watertight, but they are also water vapour permeable, meaning ‘vapour diffusible or 'breathable’ as they are sometimes described. Therefore these resin flooring systems will continue to allow the concrete below to dry out’ under the freshly applied and fully bonded resin flooring system, by gradual water vapour diffusion through the system.

Additionally, if your project does require the use of a vapour-tight resin floor in order to meet your heavy duty exposure or other special performance requirements, then it is still possible to do the work successfully, by using one or more of the following solutions:-

• Using additional drying equipment.
• Using special water reducing admixtures in the concrete.
• Using a special moisture barrier system from us (such as Sika EpoCem technology)

....before applying the selected vapour-tight resin flooring system.

Obviously all of these have different time/cost and technical implications dependant on the project, so in these instances we recommend you speak to the resin flooring specialists from any of our offices, who will be pleased to assist you in identifying the fastest and most cost effective solution to support your business.

For successful resin flooring it is also essential to ensure that the surface has not been ‘over-finished’, which can make the surface not only very dense and impermeable, but also weak and friable – This weak but brittle surface layer is known as ‘cement laitance’ and it’s presence means that the resin flooring will not bond or penetrate into the concrete, however it will probably bond and ‘stick’ very well to the cement laitance layer. – But the whole of this weak surface layer will eventually then de-bond and come off – bringing with it your newly applied resin flooring. How soon this would happen is dependent on the floors exposure to traffic and variations in temperature etc. – The more frequent these stresses are imposed, then the faster the cement laitance layer will de-bond and your new resin flooring system will fail.

- If you think that you may have a cement laitance problem, we recommend that you carry out the ‘scratch test for surface strength’ and ‘water droplet test for surface permeability’ which you can find in the ‘Floor Substrate Testing’ section below, and follow our recommendations according to the results. i.e. if the surface is easily scratched to a depth of 0.3 to 2mm and yet the surface is relatively dense and impermeable then there is a cement laitance layer present that should be mechanically removed before any treatment is applied. Today vacuum blastcleaning is the best and preferred modern method of achieving this. See Mechanical Floor Preparation – Vacuum Blast Cleaning below.

- If the surface does not scratch or flake relatively easily, then there is no laitance layer present, but if the surface is very dense, very smooth and relatively impermeable, then it still requires mechanical preparation to ‘open’ the surface and increase the concrete substrate profile to achieve an optimum bond area at the surface for any resin flooring system. Again mechanical vacuum blastcleaning is the best and preferred modern method of achieving this quickly and cost effectively.

- If you think that you may have an excessive moisture content that could cause a problem, then we recommend that you carry out the ‘Moisture Mat’ test in the ‘Floor Substrate Testing’ section below and then again follow the recommendations according to your test results.

Important: If you are not confident or comfortable in handling this evaluation and would like assistance with either the testing and / or the evaluation, then we may well be able to either do or arrange this for you. So please call any of our offices and one of our technical flooring specialists will discuss the possibilities with you.

Finally, in deciding on the cleaning and preparation requirements for any new concrete floors or cement screeds, it is important to ensure that there are no Curing Agent residues on the surfaces from the concreting contractors’ finishing works.

Curing agents are usually acrylic resin or wax based and they are designed to improve the curing of the concrete by reducing the initial rate of water evaporation, therefore allowing good hydration without shrinkage cracking or excessive rates of evaporation that can result in inadequate hydration and weak surfaces prone to dusting.]

Fortunately Curing Agents are not normally now used on concrete floors and they should be specifically excluded in the specification documents for any industrial factory, warehouse or commercial facilities concrete floor that is due to receive a resin based flooring system as the final surface finish. – Please check with your architect, engineer or contractor to confirm that this is the case.

Where any curing agents have been used, it will be necessary to carry out some additional mechanical surface preparation such as vacuum blast cleaning to remove them. Their alleged ‘natural’ rate of degradation is far too varilable and so cannot be relied on in any specific time period - again please see and follow the recommendations in our ‘Mechanical Floor Preparation’ section below.

Surface Preparation of Existing Concrete and Cement Screed Floors

When applying resin flooring on existing concrete or cement screed floors, the same requirements exist as outlined above for new floors – however, it is likely that the original concrete mix water will have dried out and any cement laitance will have been removed, typically as dusting in use and under traffic, plus any residual curing agents will also have been removed by the traffic or have finally naturally degraded (as they are designed to do). However, to be certain the same tests and recommendations given above should still be carried out – see our ‘Floor Substrate Testing’ section below. The situation may not be the same everywhere on your floor, i.e. the perimeter edges and central areas or traffic aisles are likely to have surface differences from the opposite extremes of traffic and the subsequent levels of abrasion and wear.

The more obvious requirements for existing concrete and cement screed floors are all concerned with the need for cleaning and possibly repairing any surface damage or cracks etc., all prior to applying the appropriate new resin flooring system.

This normally involves thorough detergent cleaning, followed by rinsing with clean water, or by using a combination of mechanical cleaning equipment, steam cleaning equipment or simply brushing off the surface, that is appropriate to the dirt and contamination that exists. Rinsing thoroughly after any necessary cleaning, with clean water and preferably then wet vacuuming to remove the residue, is then essential to ensure the removal of all of the dirt and the cleaning materials.

The concrete floor surfaces must then be allowed to dry for a minimum of at least 2 days. The necessary actual time allowed for this drying should be appropriate to the amount of cleaning water used and the ambient temperatures in the area. If there is excessive dirt and contamination then the cleaning procedure should be repeated.

If the contamination is heavy, or there are residual oils or grease in the floor, then there are special solutions and techniques that in many instances can remove these. For specific advice in these situations please call any of our offices and one of our resin flooring specialists will assist you. Photographs of existing floors or problems will often enable us to fully assess your situation and requirements more quickly – these can be emailed to us at technical@nccinaction.co.uk

If there is any surface damage, cracks or joints with damaged arrises (joint edges), in the floor area to be treated, then floor repairs must also be carried out and repaired appropriately prior to the application of any resin flooring. Please refer to the ‘Floor Repairs and Cracked Floor Repair’ page.

So in summary, the principle requirements for successfully applying any resin flooring are a sound, clean, dry, open textured concrete / screed surface that will allow the resin floor to appropriately penetrate and / or bond to its surface.

Floor Substrate Testing for Resin Flooring Installation

At Resin Flooring Site we have tried to summarise some simple and practical tests that you can do with commonly available materials and equipment, to test the condition and therefore the surface preparation requirements for successful resin flooring on your project.

As previously outlined above, if you are uncertain of the condition of your existing floor, then we may well be able to do it, or arrange for someone to carry this out for you, please call any of our offices and one of our Resin Flooring specialists will be pleased to assist you and discuss the possibilities for your specific project.

i) Surface Permeability / Absorbency Test (Water Droplet Testing)

The application of single droplets of water onto a concrete surface, observing any movement, and monitoring their rate of absorbency can give a good indication of the surface density and permeability, the presence of any previous surface treatments and therefore confirm if a resin floor material will successfully be able to penetrate into the concrete.

Water droplet testing should be carried out using groups of approximately 6 water droplets in each part of the floor, and on any areas that are discernibly different in appearance or texture / profile. Place the droplets using a simple ‘dropper’, syringe or pipette (available from any chemist). Place them together within an area approximately 10cm x 10cm, and be sure to always test at least the centre and the perimeter areas of your floor – as these can often be finished differently by concrete contractors and they are also trafficked differently in service.

Dense Concrete Surfaces – i.e. smooth, hard and almost ‘shiny’ surfaces

i.e. if these areas are to receive a resin floor of any kind and then be subject to vehicular traffic or other aggressive exposure and loading, then additional mechanical preparation is required to open the surface and ensure good penetration / adhesion of the resin flooring.

Open Textured Concrete Surfaces i.e. – concrete surfaces that are ‘dull’ and not shiny in any areas, or which may have already been mechanically prepared i.e. by grinding for other construction reasons (such as wall construction etc.).

These concrete surfaces are therefore suitable for the direct application of a resin flooring system, after the thorough cleaning and removal of any dirt and dust – preferably by use of a suitable industrial strength vacuum cleaner.

A Typical Table of Results and Conclusions from the Water Droplet Test

Project Area 1	Central Part	All Droplets	Observed at times of 30 seconds, 1 min, 5 mins. Result = No absorbency. Observed at 10 mins. Result = Slight absorbency (5mm darkened ring when droplet removed with a cloth from the surface).
	Perimeter	All Droplets	Immediately evident absorbency. At 5 min – all droplets completely absorbed (5-10mm darker ring).
Project Area 2	Central Part	All Droplets	Observed at times of 30 seconds, 1 min, 5 min – No absorbency. 10 min – slight absorbency (5mm darker ring).
	Perimeter	All Droplets	Immediately evident absorbency. At 5 min – All droplets completely absorbed (5-10mm darker ring).

Test Conclusions from this Example: In this example it is evident that the perimeter of both areas has a different concrete surface to the central area – this could be due to the central areas being power floated and the perimeters being hand trowelled (i.e. there has been less ‘finishing’ and there has not been so much laitance brought to the surface, or it is a very good, dense, non-absorbent concrete surface – with or without an additional curing agent applied). Alternatively the perimeter areas may have been ground with a grinding machine to ensure a good ‘key’ for building brickwork walls.

In either situation the concrete floor definitely requires additional mechanical preparation before successfully applying a resin floor finish. The most practical and cost effective solution is vacuum blastcleaning, which will generally cost approximately £32 to £54 per square metre, dependent on the size of the area and ease of access, existing surface and environment etc.

Alternative mechanical surface preparation could include mechanical grinding at a similar cost. Rotary Scabbling would be more expensive and more destructive as it fractures larger aggregates and creates a rougher profile that is more commonly only suitable and used as surface preparation for resin floor screeds of at least 6-9mm thickness. It is not suitable for self-smoothening resin floors of 2 to 5mm thickness or resin floor paints and coatings, which are normally applied in 2 or 3 coats to a total thickness of 150 to 500 microns (0.15 to 0.5mm) thickness. Acid etching should never be used as the floor preparation for resin flooring - As explained in more detail below in Section 4.

ii) Surface Strength – Scratch Testing / Cross Hatch Testing

There are a number of tests for this involving expensive equipment from Schmidt Hammers to Nuclear Density Testing Machines – However there are some less expensive practical tests that anyone can do with basic equipment to give a very good indication of the surface strength and condition.

Concrete surfaces can be assessed with the simple surface ‘Scratch Test’, by carefully using a new ‘Stanley knife’ blade against a metal straight edge to try and cut into the concrete surface vertically over a length of about 30cm; and then also with the ‘Cross Hatch’ test using another of the same type of (new) sharp knife blades. This cross hatching should be produced in a grid of at least 5 vertical and 5 diagonally crossing horizontal lines, each at least 30mm in length and with approximately 2 to 3mm spacing.

Then apply and quickly remove ‘gaffer’ or similar strong adhesive tape and examine the results for the depth of the cuts and if there is any discernible fracture or flaking off of the concrete surface around the cross hatch cuts which will therefore be visible on the back of the tape.

(A similar cross hatch test is also widely used for assessing the adhesion performance of paint coatings on steel and other material surfaces).

Surface Scratch Test – No visible / significant cut dimensions

Cross Hatch Test – No visible cuts or flaking on the back of the tape

iii) Considering the Moisture Content – Moisture Meters and the Moisture Mat Test

The moisture content of a concrete floor or cement screed is also a very important factor in achieving a successful resin flooring job. This applies to both new and existing floors and relates to the original excess concrete mix water, i.e. the water content of the fresh concrete that must be allowed to evaporate; or alternatively the presence and integrity (or not) of an adequate Damp Proof Membrane (DPM) beneath the slab; or the presence and integrity (or not) of any water supply or drainage system through the concrete; or the areas exposure to rainfall or water from cleaning or other processes.

As stated previously the general rule for resin flooring application on concrete floors is that for a vapour-tight resin floor to be applied successfully, the substrate moisture content must be less than or equal to 4% by volume of the concrete.

To explain this briefly:

An average concrete mix per m³ today is:	400 kgs cement
	1800 kgs sand and aggregates
	200 kgs / litres of water

As the concrete hardening process (hydration) uses only around 100 litres (0.27 W:C ratio), there are therefore, approximately 100 litres of extra water per m³ that need to come out – and as a new floor should always have a good DPM below it , then the vast majority of this water must come out through evaporation from the floor surface. With a typical 200mm thick industrial / commercial concrete floor slab, one cubic metre of concrete provides 5 square metres of floor – This means there are 20 litres of water that need to evaporate from every square metre – A considerable amount.

This hopefully also explains why adequate ventilation and curing techniques are also important for the correct curing and hardening of the concrete floor. In order to ensure uniform strength, particularly of the new concrete surface, this rate of water evaporation must be minimised and controlled in its early stages, so that the evaporation pore diameter is small, and that the surface layer itself hydrates and hardens correctly – Otherwise it will be weak, porous, easy to wear and prone to dusting. This is normally achieved by covering the freshly laid and finished concrete with a combination of hessian, plastic sheeting, or even special curing mats.

Alternatively resin or wax based Curing Agents can be sprayed on the freshly finished floor surface to act as a barrier and reduce the rate of evaporation. However, as previously mentioned, this method is totally inappropriate when a subsequent floor paint or resin floor is to be applied.

New concrete should normally remain covered for 2 to 3 weeks followed by a further period of at least 2 weeks uncovered, but protected from the weather, and with good ventilation. This results in the minimum 28 day ‘rule of thumb’ period of curing prior to any Resin Flooring works being carried out.

However as this is obviously a very generalised rule, given all the possible variables, at Resin Flooring Site we always recommend that the actual moisture content of a floor is tested and in several representative areas, to confirm compliance with the requirements of the resin flooring system selected. This is exactly the same requirement on both new and existing concrete and cement screed floors.

iii. a. Measuring the Concrete Floors Water / Moisture Content

Fortunately this is easily done by measuring the actual moisture content with a surface moisture meter (such as a Tramex meter), which are now widely available (Cost around £300 to £600 according to capabilities.) However the test procedure itself is also critically important because the meter will only measure the moisture content of the surface (as the name says), which does not take into account the residual moisture throughout the rest of the slab, or water moving through the slab as water vapour to evaporate from the surface.

Different Tramex Moisture Meters are available to suit different testing requirements, At Resin Flooring Site we can advise on the most suitable equipment for your project – In most concrete flooring situations the cheaper surface measuring moisture meters are ideal, provided the test procedure is carried out correctly.

Therefore the areas selected to be tested must first be covered with a dense, impermeable plastic or rubber mat, with dimensions of at least 600mm x 600mm (USA standards propose 900mm x 900mm) for a period of at least 24 hours before removing and immediately testing the moisture content of the surface beneath it in several places (Take an average of at least 3 results.)

As a tip: If water droplets are present or a significantly darker patch has developed when the mat is lifted, then further waiting and drying or an alternative vapour diffusible resin flooring system is necessary.

Resin Flooring Site can usually arrange to help you test the moisture content of your floor in an appropriate way, by using our own equipment, or by putting you in touch with a local specialist having the right equipment and experience to assist you. Please call any of our offices and one of our Resin Flooring specialists will be pleased to assist you.

Concrete and Cement Screed Surface Preparation Methods

When mechanical concrete surface preparation is required in addition to surface cleaning, then there are now a number of cost effective modern techniques and types of equipment available so that you can buy own for your own use. There are also specialist Floor Preparation Companies and Resin Flooring Contractors who can carry out this service for you – including the Resin Flooring system application and detailing as well, if you would prefer it.

Resin Flooring Site have a network of these specialists throughout the UK who can do this work quickly and efficiently – for details please contact any of our offices and one of our flooring specialists will be pleased to assist you.

Below we have tried to present a summer and introduction to the most commonly used and widely available floor preparation and cleaning methods and equipment in the UK today which include:

i) Acid Etching We include and reference acid etching in this guide as it still persists in some areas of the country. However - Please do not use ‘acid etching’ on your project – It is out of date, dangerous and damaging to your structure (whatever nonsense you are told!) This is now only proposed by a few people from the dark ages who have yet to update themselves with the latest technologies and advice in regards to reinforced concrete, cement screeds, resin floors, floor paints and / or additionally the latest UK Health and Safety Legislation.

All of the UK Flooring Trade Associations such as FeRFA and the PMA now also clearly state that ‘acid etching of concrete floors is not recommended. So – Not a particularly good place or indeed people to start a quality resin flooring project!

This is basically for a combination of health, environment and floor durability reasons, because the concentrated and diluted acids used (normally Hydrochloric/Muriatic or Phosphoric Acids) all facilitate extreme danger in transport, handling and application in the home or on site, particularly with the large quantities required to etch a concrete floor. That hazard is both from the potential direct acid contact with skin and eyes, plus the risk of breathing unknown fumes when it reacts and attacks the concrete surface and any contaminants in or on the surface. The vapours will therefore depend on the precise type of ‘dirt or contamination’ on the floor and how it reacts with the acid – Would you like to breathe these?

Additionally, it is almost impossible to adequately reclaim, neutralise and safely dispose of the large volume of liquid residue – It is now strictly illegal to allow any of this waste water to enter the drainage system. Everybody involved in any such action - the individuals, the contractors and the facilities management and owners can ALL be charged and heavily fined by the Environment Agency and the Local Authority.

Finally the acid will of course also penetrate any cracks or joints in the concrete floor and therefore attack stanchions or machine fixings and steel reinforcement causing accelerated steel corrosion – as it will also attack any steel plant or equipment on the floor; plus effective acid etching requires the concrete to be absolutely saturated before the acid application, followed by multiple rinsing with clean water to remove it (which also significantly extends the floor drying and waiting times. The calcareous and other soluble salts produced in the acid’s reaction with the concrete surface are also inevitably left in the concrete. These can subsequently cause osmotic blistering or de-bonding and delamination of resin floors, even several weeks or many months later and after what may have initially seemed to be a successful job was ‘completed’.

SO PLEASE DO NOT ACID ETCH YOUR FLOORS – it is never worth the risks – If surface preparation is necessary then it makes sense to use mechanical grinding or vacuum blastcleaning, especially with the extremely efficient and cost effective equipment now available for hire – or you can get a local floor preparation specialist to do it – we can recommend many competent floor preparation contractors that can prepare your floor, or even to do the whole job and apply the resin flooring system for your project – anywhere in the UK mainland.

ii) Mechanical Surface Preparation

The developments in mechanical floor preparation equipment has been considerable over the last 10-20 years, with modern purpose made vacuum blastcleaning, grinding and rotary scabbling machines now widely available, which are fast, precise, controlled and almost dust free. Therefore they are also very cost effective.

At Resin Flooring Site we can provide you with details on the most appropriate surface cleaning and preparation methods and equipment to use for your project, together with the names of hire companies that will rent you these machines or, if you prefer, specialist floor preparation contractors that are very experienced in their use, so can usually do the work for you even more competitively than you can yourself! Indeed most of the UK’s major resin flooring contractors also now use these specialist companies to do their preparation work. Therefore it is very often cost effective to get one of our specialist resin flooring contractors to do the whole job for you and provide a guaranteed floor finish – especially on larger areas over a few hundred square metres.

For details on specific floor preparation equipment, floor preparation contractors or resin flooring contractors near you, please call any of our offices and one of our Resin Flooring specialists will be pleased to assist you.

The following is a brief overview of the different mechanical floor preparation techniques and equipment now available:

ii. a. Hand Wire Brushing

Whilst this is not really ‘mechanical equipment’ and obviously impractical for large industrial or commercial areas, hand wire brushing can be useful, practical and cheap for smaller areas, such as domestic garages or workshops, etc., and around the floor edges in areas of difficult access.

Hand wire brushing will not be suitable for dense power floated concrete floors as they will not be strong enough and may only polish the surface some more – stronger mechanical equipment will be required for these surfaces – see below.

ii. b. Mechanical Grinding

This type of machine was one of the most widely used types of mechanical floor preparation equipment, but it lost market share with the improved development of vacuum blastcleaning machines. The main reasons for this being that they had more speed and uniformity of finish, plus the technical argument that grinding can force dust into the surface pores and therefore this can create an ‘integral de-bonding agent’ or even ‘polish’ the concrete surface and reduce the subsequent adhesion of a resin floor system.

However in recent years the grinding machinery and manufacturers have also progressed and developed efficient vacuum floor grinding machines with different grinding ‘heads’ ; certainly on small to medium sized projects up to a few hundred metres squared, these can provide an efficient and cost effective solution. Generally wire brush ‘heads’ should be avoided for this purpose as they do tend to polish dense floor surfaces.

Good mechanical grinding machinery manufacturers include HTC (Swedish), Asuga (Danish) and Klindex-Chemspec-Samich (Italian) – and most probably with components from the Far East – But generally today they all work well, although individual contractors will have their own personal preferences – usually for what they own or can get locally at a reasonable rate. We do not currently know any that are still made in the UK.

Typical Modern Floor Grinding Machines and their Vacuum Dust Extraction Attachment

These modern machines and their variety of diamond, carborundum and synthetic grinding heads are in fact clearly the best equipment to use if the floors to be prepared are wet or damp (vacuum blastcleaning machines do not work at all well on damp / wet concrete surfaces); if the surfaces are uneven and profiled (the grinding action also increases uniformity and reduces any excessive profiles that would adversely reflect through a floor paint or relatively thin resin flooring); plus if old residues of elastomeric coatings, bituminous material or flexible / elastic adhesive residues exist, such as those used for some floor tiles or vinyl products. (Vacuum blastcleaning does not remove these materials very well as the impact of the shot is deflected or absorbed by these materials.)

Mechanical grinding machines are available to hire or there are specialist floor preparation contractors who can do this work efficiently and effectively for you. As a guide, dependent of the type of machine and floor condition, access, etc., up to 1000m² per day can be readily achieved in floor grinding!

For advice on the right mechanical grinding equipment for your specific project please call any of our offices and one of our Resin Flooring specialists will be pleased to assist you.

ii. c. Mechanical Blastcleaning / Vacuum Blastcleaning

The principle of blastcleaning is firing sand, grit or steel shot abrasive at high velocity in a stream of air, at an angle on to the concrete surface. This localised impact removes any loose or friable materials and it also locally fractures and very effectively removes any brittle layers, such as the cement laitance.

This used to be a very noisy, dirty, dusty and disruptive process, but the development of modern high performance and very efficient machines with integral vacuum collection of the dust and waste, plus the use of recoverable steel shot, means that the process is now very fast, clean and controllable, and it is now almost completely dust free.

Due to the partially magnetic recycling process, the abrasive used in these modern machines should always now be rounded steel shot, rather than non-magnetic slag, grit or sand.

Small machines are available for hire with a 200 to 250mm wide enclosed head that can prepare approximately 50m²/hour – these cost around £300 per day or £800 per week, (always get a magnetic roller for around £15/day as well, to recover and recycle more of the shot and therefore save costs on bags of shot that are around £40 per 25 kg bag).

A Typical Small Vacuum Blastcleaning Machine and Dust Extraction Attachment

Medium sized machines capable of preparing around or even over 100m²/hour are available from around £450/day; however these usually require 3 phase electrical supply. Large machines, including ride on equipment are available for very large areas but these are not available for hire and only suitable for professional use.

Typical Medium Sized Vacuum Blastcleaning Machines

Resin Flooring Site can advise you on the most appropriate vacuum blastcleaning machines and equipment for your project, plus where you can hire them. We can also put you in touch with professional floor preparation contractors who are very experienced and can therefore carry out your floor preparation works efficiently and cost effectively for you.

Please call any of our offices and one of our Resin Flooring specialists will be delighted to assist you

We hope the information relating to your industry area and project is useful and of initial assistance. You are also welcome to call us for our FREE support at any time on: 01257 266696 Alternatively, you can email us technical@resinflooringsite.co.uk and we will get back to you just as soon as we can.