Bund Lining Materials began to be provided some years ago at their simplest and cheapest level with bitumen based paint products.
Bitumen based products were therefore the traditional option for bund and waste water tank linings, but whilst relatively cheap and easy to use, they also have inherent disadvantages. This includes softening at higher temperatures and embrittlement at lower temperatures, plus degradation in UV light and a general lack of resistance to other hydrocarbon based materials such as fuels, oils and industrial solvents for example. The combination of these disadvantages or weaknesses makes them out dated in most situations and so today they are not normally recommended for bund and containment area linings by NCC’s protective coating and bund lining specialists.
Protective coating systems based on modern synthetic resin technologies are now the most common Bund Lining materials used in the UK and around the developed world. The difficulty is that there are now so many different types of resin and then very different types of products with different application characteristics and performance properties can be formulated with each generic resin. However there are some general characteristics and guidelines that we can apply from experience, without everybody requiring a PhD in organic chemistry and ignoring the frequently misguided bias, generalisations and half-truths based on hearsay and the like that you will undoubtedly get from some so-called specialist contractors and materials manufacturers – there are far to many big wors and opportunities for mixing them up in this area of the construction business!!!
Here you can go directly to the specific aspect of Bund Lining Materials, or the Resin Technology that you are interested in from the list below, or you can scroll down to review information on all of the different aspects of bund lining system build-ups and resin and / or fabric technologies and systems, using all of these different types of synthetic resin based bund lining materials.
If you need any specific advice or assistance on your particular project, then please call any of our offices and one of our protective bund lining experts will be pleased to help you:
1). Bund Lining Systems - Alternative Lining System ‘Build-ups’
2). Bund Lining Systems - Alternative Lining Resin Types
3). Epoxy Resin Bund Lining & Coating Systems
3i). Water Based Epoxy Resin Lining & Coating Systems
3ii). Solvent-Free Epoxy Resin Lining & Coating Systems
3iii). Phenolic Epoxy Resin Based Lining & Coating Systems
4). Vinyl Ester Resin Bund Lining Systems
5). Polyurethane Resin Bund Lining Systems
6). Polyurea Bund Lining Systems
1. Bund Lining Systems - Alternative Bund Lining Build-ups
There are basically three main alternative ways of building-up a resin lining or protective coating system in bunds and containment areas on site. This is firstly dependent on the types of resin systems / products selected and then the best system build-up method for each project is determined by a number of other factors including: the substrate profile after surface preparation has been completed – i.e. what pre-treatment and priming is required; the total resin system thickness required for the defined performance; the specific resin products selected - including their consistency, pot-life, application method / characteristics and any environmental or other limitations, including the possibility for the release and escape of any solvent or water contained in any of the system components, plus the products tolerance and sensitivity to the environmental conditions itself – normally moisture and / or temperature sensitivity must be considered.
The alternative bund lining system build-ups that are most commonly used are:
- Multi-Coat Rolled or Sprayed Bund Lining System Build-ups
- Self-Smoothing Bund Lining System Build-ups
- Trowel Applied Bund Lining - Screeded System Build-ups
These methods and the difference between these different build-ups of resin bund linings and protective coating systems for containment area can be summarized as follows:
Multi-Coat Rolled or Sprayed Bund Lining Systems
The resin bund lining system is built up from a number of layers of the same or compatible resin products that are generally brush, roller or spray applied, as thick-layer or ‘high build’ coatings, that are thereby ‘built up’ and create the defined system thickness and structure required.
Spray application is obviously the fastest method for larger areas, but brush or roller application may be more suitable for porous and textured or roughened surfaces – This is done to ensure that there is no surface pinholing or voids in the material, which is particularly important with the first or priming layer of the system that is critical for adhesion to the substrate. Multi-coat resin build-up systems are the most commonly used bund lining solution today and they are normally used for Bund Linings and protective containment area coating systems with a total defined thickness from around 500 to 1000 microns or sometimes more (0.5 to 1.0 mm) The broadcasting of suitable aggregates into the freshly applied resin material can also be included on horizontal and slightly sloping surfaces, nin order to provide additional slip or skid resistance, which can obviously be important for areas that will also be exposed to pedestrian or vehicular traffic for access where required. Although increased profile for slip and skid resistance can make cleaning more difficult in any areas with frequent spillages, so this must also be considered and possibly slip resistant profiles can be created just in the necessary walkways or traffic routes for example.
Reinforcing materials such as special fabrics can also be embedded into the freshly applied resin coatings. These include various forms of glass, aramid and carbon fibre reinforcing fabrics that can be selected according to the exposure and performance requirements of the specific lining or containment project. Different types of lining system reinforcing fabrics can be used for many different reasons in multi-coat bund lining system build-ups. THis is because different types and grades of reinforcing fabric produced with different types (polyester, glass, aramid, carbon etc.) and different configurations (woven and non-woven, uni-directional and multi-directional etc) of fibres can be designed to: increase the load bearing capacity and strength of the structure itself; to add increased resistance to the system against impact, abrasion or blast forces; increasing lateral cohesion and reducing the possibility of any future movement; reducing or preventing cracking in the structure or substrate being reflected and going through the system, to ensure watertightness and prevent leakage or contamination for example.
As previously mentioned, these Multi-Coat System Build-ups are now the most commonly used methods of providing durable bund linings and protective coating systems for containment areas, which is due to their almost unlimited possibilities in terms of their design, structure and performance in service. With the right preparation and resin system selection they can also be installed in almost any environmental conditions, plus other advantages or functions can be incorporated such as structural strengthening and upgrading of capacity or load bearing capabilities.
Self-Smoothing Bund Lining Systems
Resin products that are trowel or squeegee blade applied for chemically resistant industrial flooring systems for example, can also provide useful bund lining systems; obviously this has to be on predominantly horizontal and slightly sloping areas, where their application and performance characteristics are suitable. However, as the walls, upstands and any other vertical surfaces in the bund or containment area, are not normally trafficked or so severely exposed to attack, thinner layers of the same or modified grades of these resin materials can be used. These are then applied on these vertical or sloping surfaces by brush, roller or spray.
Self-smoothing epoxy, vinyl ester, PU and polyurea resin systems are all usually applied in 1 to 3 layers to build up the required thickness of these systems, including the application of resin primers where required to seal porous substrates and prevent air or moisture blistering in the subsequent top coating layer. The intermediate or top coating materials are then applied at thicknesses of from 2-6 mm in total, according to the specified lining system requirements. The freshly applied resin layer is then rolled in two diametrically opposed directions with a ‘spiked-roller’ whilst it is still ‘wet’, to remove any entrained air from the mixing and application operations; plus encourage the flow or self-smoothing of the material before it cures and hardens. This surface can then either be left smooth as an easy to clean finish, or alternatively, whilst still ‘tacky’, it can be broadcast with fine graded sand or other synthetic aggregates, with or without an additional sealer coat of the resin, to provide an increased level of slip or skid resistance.
Trowel Applied Bund Lining - Screeded Systems
These are the type of bund lining systems that are used to provide the highest levels of mechanical impact, abrasion and thermal shock resistance. This type of resin system is produced with trowel applied resin mortar systems that are usually based on solvent free resins to prevent any voids or entrapment. The resin is highly filled with selected and graded special sands, or other specially prepared hard aggregates, in order to provide the high impact, wear and shock resistance demanded. These are obviously easier to use and install on predominantly horizontal or only slightly sloping surfaces and limited areas of any associated upstands – where the full mechanical abrasion and wear resistance is less likely to be necessary and thinner coating layers of the resin material alone can be used to provide the chemical resistance and any other specified performance and properties.
Therefore these trowel applied resin screed system build-ups for bund linings are normally laid with traditional‘floor-screeding’ techniques, including machine mortar screeding and power-float finishing techniques. The thickness of trowel appliedresin systems is normally recommended and specified to be from an absolute minimum of 4mm, and more frequently from at least 6 to 9mm in total. This is in order to get the maximum advantages and benefits from this type of protective resin surfacing system i.e. the increased mechanical impact, wear and thermal shock resistance etc. These trowelled mortar bund lining systems can be laid so that they are impermeable in themselves, which is why they are widely used for hygienic, easily cleaned, chemical and abrasion resistant floor finishes in the food and beverage industries for example. However, there may also be an additional requirement for afinal resin sealer coat of the same pigmented resin binder, or possibly another resin based sealing coating, where absolute impermeability and the highest chemical resistance is required – this coating will be brush, roller or spray applied dependent on the material selected for this purpose.
Selecting Your Bund Lining System and the Optimum System Build-up
If you would like any additional help and assistance in selecting the right type of resin system and the appropriate ‘build-up’ for your project,with specific advice and guidance on any aspect of your Bund Lining– no matter what size the area, or your performance demands, then please call any of our offices and one of our specialists will be pleased to assist you.
2). Bund Lining Systems: The Alternative Resin Types
Bund Lining systems can be produced from several different synthetic resin technologies that are predominantly reaction hardening, which means they harden or set into a solid lining material on the surface of the area you are protecting, as the result of mixing their two or more components together and applying the liquid mixed product at the specified thickness. This mixing is obviously a critical step that must be done correctly to ensure that a fully homogeneous product is applied. It is therefore usually done with special low speed mechanical mixing equipment and in in each individual products defined mix ratio. Generally resin lining and protective coating products are supplied pre-batched in the right proportions to be mixed together, although on larger projects some contractors with specialist equipment, can handle bulk supplies of the products component parts, which can significantly reduce costs and packaging waste. Mixing of 2-component synthetic resins must always be done thoroughly and for a defined period of time, shortly before application and sometimes, with spray applied resin coating systems, the two-components are actually mixed together at the nozzle as they are being spray applied – usually the best solution for fast and very fast curring and setting resins such as 2-component VIP Quickcoat Polyurea resin based protective coating and lining systems.
One-Component Bund Lining Materials
One / single component resin materials are not generally suitable for use in industrial and commercial facilities for their Bund Lining applications as these are usually exposed and / or trafficked. This is due to their lower inherent mechanical strengths and chemical resistance, which means tha they will not be sufficiently resistant and durable in these situations.
However there are one component Bund Lining Materials that can be more than adequate for domestic or limited commercial applications with limited exposure and traffice, where their properties are therefore adequate – for example in domestic fuel oil storage tank areas.
For these straightforward external applications NCC Bund Lining experts tend to propose the use of Sikafloor®-400 N Elastic, which is a one part, easy to apply, highly elastic, solvent containing, crack-bridging, waterproof and UV resistant, coloured, moisture curing polyurethane resin based protective coating that is fully resistant to domestic oil and sewage, plus many other dilute chemicals.
Sikafloor®-400 N Elastic has also been tested and certified as a resistant top coat in the “Ground Water Protection System”, according to German Standards Z-59.12-4, DIBt, dated June 2003.
Despite the relatively good performance from this one / single component resin product in particular, on almost every industrial and commercial project we prefer to recommend the use of higher performance two-component resin based lining and protective coating systems as increased security for our contracting customers and their clients. However if the areas future exposure is strictly limited and controlled, then the use of the relatively low-cost, one-component Sikafloor®-400 N Elastic lining system can always be considered.
Two-Component Bund Lining Materials
The most commonly and widely used Bund Lining material technologies used in the UK are two-component resin based systems. These include 2-part epoxy resin coating systems, 2-part polyurethane resin coating systems, 2-part vinyl ester resin systems and 2-part polyurea resin systems.
All of these different ‘2-part’synthetic resin Bund Lining systems, or ‘2-component’ Bund Lining materials as they are more correctly known, are generally all supplied to site as separate units that are pre-batched in the correct proportions, which are known as the products ‘mixing ratio’.Alternatively for large projects and contractors with the necessary specialist equipment, each individual component can be supplied to site in bulk containers. This means that the components must be correctly measured and dosed on site following strict Quality Control procedures and as much of the process automated as possible to reduce the risk of human error.
The two components of these systems are generally referred to as the ‘resin base’ and the ‘resin hardener’ or ‘resin catalyst’, whichare then required to be thoroughly mixed together.
Technical note: the second component is the ‘resin hardener’ if it takes part in the reaction and forms part of the structures of the cured and hardened resin product; whilst it is a’resin catalyst’ if the material simply triggers or accelerates the hardening reaction, but does not physically take part in it or change and is therefore still there in the same form at the end. Basically in these instances, the reaction tends to start because it is physically accelerated on the surface of the catalyst, which is also why 2-component resin catalysts are generally in the form of powder, because the use of fine particles means the material has the largest possible surface area for this initial acceleration to take place and start the reaction throughout all of the mixed material. In both cases with a hardener and a catylst there is often associated heat generated (the reactions are exothermic) and this will also accelerate the reaction and so this must be controlled by only mixing sufficient volumes that can be used immediately for example.
The mixed resin lining / coating material is then applied onto the prepared concrete substrate and this must be undertaken and completed within the products defined ‘pot-life’. This means its ‘working time’ or ‘useable time’ which is normally defined at given ambient and substrate temperatures and humidities, before it has become too thick or otherwise is unworkable or otherwise over this limit and so can no longer be applied. There is a useful old 'rule-of-thumb' that has been used on site over the years by experienced resin specialists, which says that: "an increase of 10°C will roughly halve a product’s pot-life, whilst a drop of 10°C will roughly double the pot-life" – however the manufacturers specific recommendations and advice must always be ollowed for each individual product of course.
As a note of caution there are also some 2-component resin systems where this critical change is not easily or visably perceived, so extreme care should be taken i.e. with some water dispersed acrylic resin based injection and surface sealing solutions.
With reaction hardening resin products the two components begin to react with each other as soon as they start to be mixed together. Once mixed the product hardens to form a durable resin lining in it's defined hardening, or curing time as this is known, which is also normally defined and stated at given ambient and substrate temperatures and humidities. This reaction time is also referred to as the resin materials ‘hardening’ or ‘curing’ time and this is also generally reduced at higher temperatures and increased at lower temperatures – and the same rule of thumb from experienced resin specialists also generally applies to this i.e. an increase of 10°C will roughly halve the hardening time, whilst a drop of 10°C will roughly double the hardening time - (although always check and observe the specilialist product manufacturers stated limitations in the PDS).
The length of time before the area can be put into use will then vary according to the type of resin system, from immediately with some systems, to several days with others, which again will be temperature and humidity dependent. Additionally some two-component resin based bund lining and coating systems may require protection from the elements or exposure to water, chemicals or traffic for all or some of this period.
Typically the initial curing time for 2-component resins can be from 1 to 24 hours (although as little as a few minutes or even less with some special products mixed at the nozzle such as some of the VIP polyurea systems), with additional time possibly being required for the products full chemical and mechanical / abrasion resistance to be achieved, typically in from 1 to 7 days – again this is all dependent on the resin type, the specific product formulation, the application conditions and the intended exposure. A full understanding of the site, the environmental conditions, and the Bund Lining system product application and performance are therefore all essential for a successful and durable installation.
The Bund Lining specialists at NCC can always advise you on the most suitableBund Lining type and the best specific Bund Lining product(s) for your specific project needs. Please call any of our offices for specific assistance from our experts.
The following pages of generic information on the different types of resin Bund Lining materials technologies, is intended to provide you with an overview of the typical and characteristic properties of each of the different types of synthetic resin lining and protective coating materials – Although as we have already cautioned, almost by definition within any generic group there can be substantial and wide variations in the different products application and performance characteristics due to the range of resin chemistry formulation possibilities. However in the following pages of this website we will try to review and discuss each of these resin materials technologies in more detail, to help you to understand the alternative possibilities that are available, together with their main advantages and any limitations in relation to their use. Hopefully this will be of assistance in defining and selecting the best type of Bund Lining system for the protection of primary or secondary containment areas for your project.
If you would like any additional advice or assistance for your Bund Lining project then please call any of our offices and one of our experts will be delighted to assist you. NCC provide FREE independent and detailed advice and can supply the full range of the best performing Bund Lining technologies and protective coating systems that are available on the market today.
3. Epoxy Resin Coating & Bund Lining Systems
Epoxy resin coatings and bund lining systems are probably now the best known and most commonly used type of materials used for bund lining and to provide protective coating systems to containment tanks and other bunded containment areas throughout industrial and commercial facilities in the UK. However it must be clearly understood that there are actually many different types of epoxy resins and epoxy resin based protective coatings and linings, with some quite widely different application characteristics and different performance properties. ‘Epoxy resin’ is a very broad generic term that one recent technical author suggested was rather like saying you need a method of transport with an internal combustion engine – the possibilities and variations range from mopeds to aircraft, boats to trains, Smart cars to Big Macks or Ferrari’s – i.e. there are a lot of otions and they vary greatly in terms of their appearance, size, strength, power, speed, fuel consumption, load carrying ability, maintenance requirements and durability etc.
Epoxy Resin Coating & Lining Types
Epoxy resin based products that are used as bund lining materials include:
Water dispersed epoxy resins (also commonly incorrectly known as ‘water based epoxy resin coatings – they are of course epoxy resin based, and are actually produced from solid epoxy resins that are water dispersible until they are mixed,the epoxy resin reacts and hardens whilst the water evaporates).
Solvent dispersed epoxy resins – these are similar to the water dispersed products but the water is replaced by a hydrocarbon solvent.
Solvent free epoxy resins – there is no solvent or water required to disperse these resins , which have a liquid consistence until theyare mixed and react with their hardener to form a solid.
Phenolic epoxy resins –or ‘Novolac epoxy resins as they are sometimes called after the original material - These are a phenolic compound modified version of the solvent free type and generally these are the type of epoxy resin coating system that have the highest chemical resistance for an 'epoxy' based material.
As always with resin coating technologies, whilst these different types of ‘epoxy resin’ coating and bund lining materials have some similarities in their generic structure, all of these different types of materials also have their own distinct and characteristic advantages, disadvantages, limitations and benefits for their use as protective coatings in containment are as and bund linings. We have tried to summarise the key points of these below and in the following epoxy resin coating and bund lining materials pages to assist you on your projects.
Epoxy Resin Coating & Linings Mixing & Application
The nature and chemistry of epoxy resin products generally makes them the easiest, most reliable and cost effective resin coating materials to mix and apply on site, where they canprovide durable protective coating and lining systems that can last for many years. The mix ratio of a base epoxy resin component to the hardener component, is usually formulated to be around - 4 parts to 1 by volume (4:1), which makes it relatively easy to control the products dosing and ensure thorough and homogenous mixing – This is unlike some other synthetic resins that have much more difficult mix ratios of up to around 20 : 1 and which therefore makes complete and thorough mixing much more difficult and critical, thereby also increasing the potential risk of problems on site.
Epoxy Resin Coating & Linings Advantages & Limitations
Today the UK industry widely accepts that correctly designed and structured epoxy resin based coating and lining systems are a proven, safe and reliable option, for many or possibly almost all but the most critical and onerous installations of primary, secondar containment tanks and bunded areas. The hardness and abraqsion resistance of these epoxy resin coating and lining materials also makes them ideal for use on containment surfaces that will also be trafficked. However, this means that they have to be comparatively rgid and therefore they are not crack-bridging for use in structures where this is an important requirement. Additionally plusbecause of their nature, they are not ideal for installation over existing wet concrete surfaces without appropriate pre-treatment – although this potential difficulty was solved for many situations a few years ago by Sika’s development of EpoCem technology. This technology combines the properties of Epoxy and Cement technologies allowing these products to be applied directly on damp substrates (e.g. whilst the concrete is still ‘green’ or damp in a wet area) and then for the fully impermeable epoxy resin based protective coating or bund lining material to be safely applied the very next day.
Two-component epoxy resin based protective coatings are therefore ideal, and frequently also provide the easiest and most cost-effective solution for the majority of containment and bund lining situations, where the extremely ‘sticky’ nature of the freshly mixed epoxy materials also helps to ensure a good and strong initial and permanent bond to the concrete substrate. The hardened ‘pull-off’ strength of the cured epoxy resin systems is much higher than the cohesive strength of concrete, i.e. meaning the epoxy system can only be removed or damaged through a physical break in the concrete itself. The potential for delamination is therefore minimised and the concrete is reliably protected against impact, wear and abrasion, plus preventing any ingress and attack from water and many other aggressive chemical liquids.
Finally another advantage of good quality epoxy resin based protective containment area coatings and bund linings is obtained through the tight cross-linking nature of the epoxy resin and hardener reaction. This can perhaps be best explained and visualised as being like a physical‘clamping’ effect, which tightly closes the hardened surface, particularly with the solvent-free materials that therefore provide the highest levels of chemical resistance due to this form of almost impenetratable ‘physical barrier’ at their surface. This means that once they have fully hardened or cured, these epoxy resin systems are extremely watertight and will have excellent resistance to immersion and exposure to a wide range of oil and chemical spillages, including aggressive industrial processing liquids and cleaning products – such as strong anionic disinfectants and detergents. Sikagard-62 (also DWI approved) and Sikagard-63 are good examples of reliable solvent-free epoxy resin based coating systems that have been used successfully as bund linings for many years.
The specialists at NCC can advise you on the most suitable epoxy resin product(s) for your specific project needs. Please call any of our offices for specific assistance from our experts.
In the following sub-pages we have also provided more specific information on the particular advantages and disadvantages of each of these different types of epoxy resin based protective coatings and bund lining systems.
3i). Water Based Epoxy Resin Coatings & Lining Materials / Water Dispersed Epoxy Resin Based Coatings & Lining Materials
Water dispersed epoxy / water based Epoxy Resin Coating materials and systems have historically been considered of limited value in bund lining and protective coatings in secondary containment areas. This was due to their comparatively low chemical and mechanical resistance when compared to other types of epoxy resin materials. However with newer and improved water dispersed resin technology they are now becoming increasingly popular for bunds and containment areas with lower levels of exposure and risk. This is of course due to the advatages they bring in easier and safer application with no solvents or unpleasant odurs, plus the fact that they can be applied on relatively new or damp concrete, plus with the top performing products such as BS 3000 and Sikafloor 2530W, they have significantly increased chemical and abrasion resistance. This is because of the advances in the technology of ‘water dispersed’ epoxy resin based technology, that has been continuously developed and greatly improved by these companies in recent years.
Advantages of Water Based / Water Dispersed Epoxy Resin Coatings & Lining Materials
The main advantages of the water based / water dispersed epoxy resin materials, are that they contain no dangerous solvents, or VOC's (Volatile Organic Compounds) as they are also now referred to, so therefore they can be used safely in occupied areas, and where people and other trades are working immediately adjacent to the area being treated. Plus they can be applied on relatively new or damp concrete surfaces, because they are watertight, yet vapour permeable, and so the hardened coating will not bubble or blister due to entrapped moisture as this can escape over time as water vapour. Additionally these water dispersed materials are not dangerous in the vicinity of naked flames, or sparking from equipment and machinery, or other works in progress. Finally and very importantly for many industries and businesses, there is no odour that can contaminate food stuffs or beverages.
The performance of all water based epoxy coatings against mechanical abrasion and chemical attack, whilst now good for the specific Sika and Remmers products mentioned, it is still and will always be somewhat lower than that provided by good quality and higher build, solvent free epoxy resin products. This is partly due to the normal dry film thicknesses applied being much higher, at more than 300 microns per coat, versus the 100 to 150 microns normally applied with water based epoxy resin products, plus their more tightly cross-linked surfaces formed by the cured resin as there is no water in these products that needs to escape by evaporation in their curing process.
However the multi-coat applications (2-3 coats) of our recommended water dispersed epoxy resin products (i.e. BS 3000 and Sikafloor 2530 W) are very definitely ideal for many domestic, commercial and light industrial, high build resin coating jobs – These applications can include bund linings and protective coatings for secondary containment areas around the primary storage or processing areas for oils, fuels and many other materials.
Water dispersed epoxy resin coating materials also have another distinct and important and possibly surprising advantage over the generally higher performance, solvent-free epoxy materials in relation to their long-term durability and maintenance. This is that whilst it is true that they may be less durable in service, particularly when trafficked, whenever their refurbishment and over-coating is eventually necessary, then the only surface preparation necessary is thorough cleaning to remove any contamination on the existing surface i.e. simply high pressure water jetting and / or detergent cleaning. This is in somewhat stark contrast to the far more complex and sensitive preparation and pre-treatment, including thorough mechanical surface preparation by abrasive keying and frequently also solvent-activation that is necessary to over-coat solvent free epoxy resin coatings i.e. by abrasive blast cleaning or mechanical grinding / sanding followed by vacuuming and then hydrocarbon solvent wiping to remove residual dust and fine particles.
Additionally due to their non-taint odour and no VOC's the water dispersed epoxy resin coatings can be maintained and overcoated indoors and in occupied areas without disruption or danger to others (also true with new coatings and bund lining work) this can be particularly important when there are anyother trades and people working in the same or adjacent areas.
Therefore in many instances the best water based / water dispersed epoxy resin coatings may not have the highest long-term abrasion and chemical resistance , but they may well have considerable other advantages on a specific project. These could be any or a combination of the facts that they are much cheaper, safer and easier to use and that they are available in almost any colour. They will allow easier over-coating with refresher coat whenever they are required -all with the minimum of surface preparation, disruption and cost. This is a very clear example of why the right product / system selection for each bund lining and protective coating project in containment areas, must always be mad with a full evaluation of all of the application and performance requirements for the specific project and its location
Remmers BS 3000 or Sikafloor 2530W water dispersed, epoxy resin based lining, flooring and vertical / wall coating systems are both absolutely ideal to meet the performance requirements for use in many different bunded and containment areas or ground water protection zones in domestic and commercial applications including garages, workshops, light traffic production assembly and storage areas–together with many other light to medium duty applications in the food and beverage industries for example.
If you would like help and assistance with the selection and use of water dispersed / water based epoxy resin systems, then please call any of our offices and one of our specialists will be pleased to assist you. Normally we can also deliver these materials direct to your site, and in the colour of your choice, within 48 hours on the UK Mainland.
3ii). Solvent-Free Epoxy Resin Based Bund Lining Materials
Solvent-free epoxy resin based protective coatings are the most commonly used type of epoxy resins for bund linings and probably also the most commonly used bund lining materials overall. These epoxy products contain no solvents or water as diluents and are therefore said to be 100% solids, although the 2-components are mixed together and applied as a liquid with varying degrees of viscosity and thixotropy. This is because when mixed ready for application, this type of epoxy resin coating product consist solely of the epoxy resin and hardener, plus any other 'fillers' included in the formulation such as pigments and special ingredients, which react and combine to form a high build, dense, vapour-tight, extremely waterproof and chemically resistant solid film with 100% of the same volume of the original two liquid components when mixed together and cured / hardened on the surface.
Solvent-free epoxy resin bund lining products are therefore formulated with a high resin content by definition and generally they can be used in much thicker layers than water dispersed or solvent containing products, where the product thickness is limited because the solvent or water used as the diluent has to escape by evaporation during the curing and hardening reaction time to prevent blistering and bubbling – This is not required with sovent-free epoxy resin systems. As a result these solvent-free epoxy resin lining and coating products also produce a tighter, denser and far less permeable surface to liquids and vapour, which also means that they can have a much higher performance in terms of their chemical resistance, plus the thicker layers mean that they can also provide greater protection against abrasion, wear and mechanical damage in your bunds and containment areas.
Perhaps one disadvantage of these materials is that as a consequence of the much higher epoxy resin content, solvent-free epoxy bund lining products are always going to be more expensive and so they are generally only used by specialist contractors for professionally installed bund lining projects. The UV light resistance is generally good and not a performance issue at the normal higher build thicknesses that these materials are used at (500 – 1000+ microns) but they will yellow over time and surface chalking will occur if exposed to direct sunlight.) Another possible disadvantage on some projects is the time that they require to harden and then achieve their full chemical and mechanical resistance, which is generally up to 7 days at average temperatures of around 20°C - In these situations where far early use and resistance is required, NCC generally recommend the alternative use of rapid hardening polyurea resin based linings such as the excellent range from VIP GmbH.
Solvent-fee epoxy resin coatings are ideal for many bund lining applications and generally these systems are designed for use in areas with medium to the more demanding and higher performance requirements i.e. they are ideal for the lining and protection of primary and secondary containment tanks and bunded containment areas forsewage and waste water treatment tanks, plus many other different industrial and other process and production areas. These systems will also provide excellent resistance to heavy pedestrian and vehicular traffic, due to their high mechanical strengths against abrasion, which is why they are also used extensively for industrial floors in production and process area flooring.
Bund Lining with Solvent-free Epoxy Resin Materials
Due to their high viscosity and thick consistency, solvent free epoxy resin lining products require very thorough ‘compulsory’ mixing with adequately powered mixing equipment prior to their application. The lack of any solvents or other diluents, which would have to be allowed to escape from the material during curing, means that solvent-free epoxy resin materials can be applied and built up in comparatively thick layers. These are normally from 0.3 mm to 2mm per layer, in a sufficient number of layers, typically 2 or 3 layers, to achive the total thickness specified for the desired level of performance. Normally at least two layers of the material are always recommended for linings and protective coatings in containment areas, to ensure that the minimum and nominal specified thickness is maintained over the whole area.
It is also common to use different colours for intermediate layers to give an easy method of visual control. The application of solvent-free epoxy resin linings and coatings can be done by several different methods to suit the specific structure and type of installation including: by brush, roller or spray as high build coatings; flow applied by trowel or squeegee, as self smoothing layers with or without the incorporation of additional fillers or fine sands / aggregates, on horizontal and slightly sloping surfaces, plus these self smoothing layers can be broadcast with graded natural or synthetic aggregates to create even more highly abrasion and wear resistant non-slip or non-skid surfaces within the containment zones.
Priming for Solvent-free Epoxy Resin Bund Lining Materials
For solvent-free epoxy resin coatings and bund linings, additional priming is not generally required, however very porous concrete substrates are usually best sealed or ‘primed’ with clear grades of the same or a similar solvent free epoxy resin product. This is to penetrate and seal the substrate within it’s surface and also eliminate or reduce any suction and ‘drag’ from the surfaces on the lining system during the application, which reduces consumption increases the speed / work rate and improves the appearance of the finish.
This initial sealing and priming also prevents any blistering or bubbling in the finished coating system due to rising air and / or moisture from within the substrate during the coatings curing time. Clear grades of solvent-free epoxy resin primers are also used to obtain increased penetration and adhesion for other types of synthetic resin coatings and bund lining systems as outlined later on this website.
As previously mentioned these solvent-free epoxy resin coatings and bund lining products are usually only recommended for use by professional specialist contractors, however where appropriate for your specific project requirements, NCC can provide guidance, training and support for their use by competent general contractors or your facility maintenance crews i.e. in processing plants and other facilities with high security or restricted access for any other reasons.
NCC also provide specialist advice and specially developed solvent-free epoxy resin coating and bund lining products forvery specific applications and industries, such as systems specially developed for use on concrete surfaces in contact with potable (drinking) water, where the materials must all have DWI Approval in the UK for this specific purpose (such as Sikagard 62N), or for use in the Nuclear Power industry where the materials must all have the highest UKAEA radiation decontamination certificates. Similar products are also now being demanded for other ‘Clean Room’ environments, or with additional defined anti-static or Electrical Static Discharge (ESD) reistance properties for example. Specific advice and these materials are also all available from the specialists at NCC Bund Linings.
If you would like help and assistance with your specific project requirements, please call any of our offices and one of our specialists will be pleased to advise and assist you.
3iii). Phenolic Epoxy Resin Based Bund Lining Systems
Phenolic Novolac epoxy resin
Phenolic epoxy resins or Novolac epoxy resins are variations and modifications developed from the technology of the old phenolic resin materials, the first synthetic resins originally developed (i.e. Bakelite) for industrial uses in chemically resistant mortars, coatings and pipe linings in the 1920’s. In phenolic epoxy or novolac epoxy resins the base epoxy resin is modified and hardened with phenol hydroxyl groupings. The chemistry of these materials is now extremely varied, and the information ‘known’ by many people who talk about them has probably got more to do with various American and other companies past marketing hype, than any real organic chemistry knowledge.
The specialists at NCC can advise you on the most suitable phenolic epoxy, novolac epoxy or other resin bund lining or protective coating solution for your specific project needs. Please call any of our offices for specific assistance from our experts.
As Buyer Beware
- There is a lot of misinformation passed on and many expensive mistakes in both selecting and in not-selecting one oof these systems on a project. As the way these materials are talked about is so frequently misleading or even completely wrong, we will try and summarise this correctly now – Our apologies that this s somewhat of a technical ‘anoraks’ page and complex if you do not have a Phd in Organic Chemistry (we don’t we are Engineers), but for those who would like the facts here they are as clear as we can summarise as follows:
The first generation of synthetic resin in the 1920’s was of the so-called phenolic resins, which were actually phenol formaldehyde resins (PF), the first such synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde – Bakelite type, mostly produced and set by heating the components (thermosetting resins). The original bulky desk telephones and today these are still mostly used in moulded resin products and applications, now particularly in the platform of printed circuit boards because they are good at being inert and produced in almost any shape, but also for pool and snooker balls or laboratory worktops due to their hard and chemically resistant nature. The main disadvantage for other construction applications is that they are heat cured and due to their hardness, they are also very rigid and not at all flexible.
Novolac resins (originally called Novolak) are a further development from the original phenol-formaldehyde (PF) resins, made when the molar ratio of the formaldehyde part to the phenol part is reduced to less than one. An amine hardener then needs to be added to crosslink and cure the material as a ‘Novolac’ resin, in a similar way to the cross-linking (curing and hardening) process of an epoxy resin. These variations are also sometimes called Phenolic Novalac Epoxy resins or various other permutations of these words in the hands of marketing people! Interestingly there are also some of these Novolac resins that themselves can then be used as hardeners for epoxy resins – more on this below.
Resols or Phenolic Resols
Resols are another development made from the original chemistry of phenol-formaldehyde resins by using a different formaldehyde to phenol molar ratio of greater than one (usually around 1.5). The phenol, formaldehyde, water and a catalyst are all mixed and then heated together, where the mix becomes thermosetting and the components react together at around 120 °C to form a highly cross-linked resin that has good hardness, good thermal stability and chemical resistance.
These resols (also known as Resoles and Phenolic Resols) are of considerable importance today that are widely used as hot-melt and hot applied adhesives for gluing and bonding many different building materials during the production and fabrication off-site in factory conditions. This includes plywood, Sterling board or Oriented Strand Boards (OSB), and many other engineered timber products and laminated sheet materials, such as the so-called Engineered Wood Flooring. There are also a few examples of Phenolic Resols being used to produce high early strength and highly acid resistant mortars for special acid resistant brick and tiling applications used in the protective lining of tanks and vessels, but these are not suitable for use on alkaline substrates such as concrete or cement mortar / render.
Phenolic and Novolac Epoxy Resins
Phenolic resins (PF) have also been developed to be used as ‘modifiers’ for various coatings including ‘two component solvent-free epoxy resins. The incorporation of phenolic resin in an epoxy resin bund lining and protective coating product formulation can be used improve the adhesion, moisture sensitivity and increase the corrosion resistance of the coating material.
Some modified phenolic resins (PF) of the Novolac type (molar mix ratio less than 1) can also be used as curing agents or hardeners for a range of different types of epoxy resin based materials. Chemically the phenolic / novolac resins used in these materials are the non-heat reactive materials, which have free phenolic-OH groups in their structure that react with the epoxy groups as a hardener with a very high degree of cross-linking. Since this curing mechanism does not produce any by-products, thick sections may be obtained without voids and stresses and with very low shrinkage, provided the reaction temperature is controlled of course. There are examples of these Novolac or Phenolic Epoxy resins used in many different construction applications including moulding, laminates, adhesives and protective coatings.
Phenolic or Novolac epoxy materials have increased chemical resistance, particularly acid resistance and hydrocarbon solvent resistance. Products with an increased level of this ‘phenolic’ (PF) ingredient, will have the highest levels of chemical and solvent resistance, but if used in a protective coating formulation there is also a consequent loss of flexibility, which must also be considered as a disadvantage. Some phenolic and novolac modified epoxy resin products are also temperature sensitive in their application on site and also they can require significant additional heat curing, which may not be practicable.
Thus – Phenolic and / or Novolac Epoxy resins are basically the same thing, but there is a lot of potential differences between specific resins and the specific products for bund linings and protective coatings that can be formulated with them – So Do Not Take Risks – Check with NCC Bund Lining Experts for the right product and system solution for your bund or secondary containment area lining.
Phenolic Epoxy Resin Based Bund Linings & Coating Systems
The potential Advantages
of Phenolic and / or Novolac Epoxy resin based bund linings and protective coatings for containment tanks, vessels and areas include:
High heat resistance
Excellent chemical resistance
Excellent solvent resistance
Excellent corrosion resistance
Hard, abrasion resistant film
The potential Disadvantages or Limitations
of Phenolic and / or Novolac Epoxy resin based bund linings and protective coatings for containment tanks, vessels and areas include:
May require heat curing
Relatively slow air cure
Non UV stable – will chalks and may discolour
As a result the primary uses of Phenolic and / or Novolac Epoxy resin based bund linings and protective coatings are generally recommended to be restricted to where extreme chemical resistance is required and there is no more practical or cost effective solution available, without the associated disadvantages. In our experience typical examples of the most common applications where it is difficult to replace these products in terms of their performance, with easier to handle and more cost effective solutions, are as steel and concrete tank linings and high risk covered containment areas in refineries and the petro-chemical industries.
The specialists at NCC can advise you on the most suitable phenolic epoxy, novolac epoxy or other alternative resin bund lining or protective coating solution for your specific project needs. Please call any of our offices for specific assistance from our protective coating and lining experts.
4). Vinyl Ester Resin Bund Lining Systems
Vinyl Ester Resins
Vinyl Ester Resin, or Vinylester as it was originally called, is a synthetic resin produced by the ‘esterification’ of an epoxy resin with an unsaturated monocarboxylic acid. ‘Esterification’ is basically the chemical term for a process involving the interaction of a compound possessing a hydroxyl group with an acid, and the elimination of water. The reaction product when the base compound used is an epoxide material is known as a ‘Vinyl Ester’, which is a solid that is then dissolved in a reactive solvent, usually styrene and by around 35 – 45% by weight.
There are also some compounds that are marketed by chemical companies as ‘Epoxy Vinyl Ester Resins’ and/or ‘Novolac Epoxy Vinyl Ester Resins’ – although these particular formulations / grades of vinyl ester resin are not for site use as they are extremely sensitive in mixing and application, so can only be used in strictly controlled factory envionments.
Vinyl Ester Resin Bund Linings
The vinyl ester resins that are suitable for use in formulating bund linings and protective coating products can be used as an alternative to polyester and epoxy materials in as the matrix or in composite materials, where they have the performance characteristics of strength, chemical resistance and cost between those of polyesters and epoxies. However, vinyl ester resins generally have a lower viscosity (approx 200 cps), than polyester (approx 500cps) and epoxy (approx 900cps), which means that products produced with them can be extremely free-flowing and easy to apply, such as in the build up of laminated Fibre / Fabric Reinforced Plastic (FRP) bund lining systems.
This applies to both factory produced prefabricated bund liners that as mentioned previously are ideal and cost effective for smaller self contained bunds, and they can also be used for larger on-site laminated system build-ups, in mortar matrices and as protective coatings, where the vinyl ester resin based product has the necessary chemical (they are particularly good for acid rsistance), mechanical resistance and other suitable – plus theyare fast curing and hardening in cmparison with most epoxies is also an advantage. However this combination of fast to very fast curing and hardening with a relatively high solvent content, means that vinyl ester resin materials cannot and should not generally be stored or used at higher temperatures for the obvious health and safety / fire risk reasons.
There is also now a so called ‘new generation’ of styrene-free vinyl ester resins or epoxy vinyl resin products that have started to be promoted, but this is mostly marketing speak and these materials should correctly be called Epoxy Acrylate Resins, as although their production and process is similar to that of the the Epoxy Vinyl Ester Resins, the modifier in the production process is a dimethacrylate, and the styrene solvent is replaced because the dimethacrylate is also used as the reactive solvent – As a result of this similarity some grades of these Epoxy Acylate ‘Vinyl Esters’ are claimed to be solvent free. However as stated this would seem to be for marketing purposes to take advantage of the well establishe corrosion resistance of Vinyl Ester Resins, as technically these products are really ‘Epoxy Acrylate Resins’ and have significantly inferior properties – NCC Bund Lining experts do not recommend them and consider they are being unwisely over-sold.
So to summarise the advantages, disadvantages and limitations of real vinyl ester resins:
Vinyl Ester Resin Bund Lining Advantages
Good resistance to acids and alkalis, including strong nitric acid
Good resistance to hydrocarbon solvents
Excellent resistance to strong oxidising agents i.e. chlorine bleach
Fast to very fast curing and hardening
Lower cost than pure epoxy resins for FRP component manufacture
Vinyl Ester Resin Bund Lining Disadvantages
Solvent containing materials
Difficult to apply at lower temperatures
Cannot be stored or used at higher temperatures
Typical Uses of Vinyl Ester Resin Bund Linings
Vinyl ester resin products are used most extensively today to manufacture FRP tanks and vessels as per BS4994: "Specification for the design and construction of vessels and storage tanks in reinforced plastics", in the off-site prefabrication of vessels and components, which are widely used in industrial equipment and structures such as for chemical storage tanks, pipes, process vessels, hoods, ducts and exhaust flues.
The air handling / cleaning and water treatment sectors are also now increasingly using vinyl ester-based composites to replace metals and achieve unique and light weight structures that also withstand corrosive attack. Vinyl ester resins also have a long history of this type of application, for example they are used to fabricate components for use in the Power Industry, particularly in Flue Gas DeSulphurisation (FGD) processes as a cost-efficient and reliable alternative to metals to withstand the highly corrosive environment of the FGD process.
They are also widely used in the marine and boat building industry due to its overall corrosion resistance and ability to withstand water absorption.
There are also a lot of useful motars produced with vinyl ester resins that are mixed to incorporate silicate and other acid / chemically resistant fillers and aggregates, including specialist products for chemically resistant screeds and brick / tile bedding and jointing materials. This type of vinyl ester resin combination is also used multi-layer Glass Flake system build-ups, which are widely use in industrial process areas with high concentrations of acid and strong oxidising agent requirements, such as those that are necessary in galvanising plants, acid production facilities and again in the Power Industry – they are particularly useful for the lower temperature condensate areas of FGDS systems to protect steel and concrete structures.
The specialists at NCC Bund Lining can advise you on the most suitable vinyl ester or other resin bund lining or protective coating solution and appropriately experienced specialist contractors for your specific project needs. Please call any of our offices for assistance from our coating and lining experts.
5). Polyurethane Resin (PU) Bund Lining & Coating Materials
For more than 25 years now, liquid applied Polyurethane resin systems have been used successfully for many different waterproofing and protective coating applications, typically for roofing, but also for trafficked structures such as bridge decks and car parking areas.
Due to their unique characteristics and mechanical properties for roof waterproofing and detailing combined with good chemical resistance and traffic resistance, polyurethane systems have become widely used for a wide variety of different waterproofing applications – from the ‘basement to the roof’ as one manufactuer says, especially where seamless solutions are preferred. These includes their use on many civil engineering structures and facilities to protect structures in both primary and secondary containment areas, wherever high-end performance and a long-lasting durable bund lining or protective coating system is required.
Polyurethane Resins (apologies a bit techy agin – but for clarity of understanding)
Chemically a polyurethane is the result of a chemical reaction between an isocyanate and a polyol. There are different polyols that can be used including polyether and polyester for example, and as a rule the resultant polyurethanes that they produce, then require the action of an appropriate catalyst in order to form a hard resin and one that can also cure rapidly.
Polyurethane / PU coating materials are often referred to by self-appointed coatings experts as ‘urethanes’– But if you hear this from anyone let it be a warning!
A ‘Polyurethane’ is completely different chemically to a ‘Urethane’, and is not produced from or made from them either! ‘Urethane’ is a name that was given to a product called Ethyl Carbamate when it was fist synthesised over a hundred years ago and this name related to its molecular bond form. Ehtly Carbamate was widely used for various medicial applications until the 1970’s when it was discovered that it may be carcinogenic to humans - -it actally occurs naturally in most fermented beverages and foods including beers, wines and spirits, but at very saall levels and nothing to worry about apparently- A good job say our relieved technical coating and lining experts due to their other main interest!
A ‘Polyurethane’ is a completely different material, which is formed from different component groups that have several bonds between these component groups that are similar in structure to the bond in Urethane – that is all and the only similarity – A polyurethane resin is acutally another type of ‘Reaction Resin’ and therefore is actually much closer in structure and nature to an epoxy resin than a urethane.
All very confusing we agree – We blame the various raw materials suppliers and product manufacturers Marketing Departments causing coinfusion over the years again – but if a self-appointed expert talks about them in front of you now, you know the truth and how much faith you can put in whatever else they suggest!
Notwithstanding all of the marketing waffle, Polyurethane Resin Bund Lining and Protective Coating systems for containment areas are available in two main types: there are one-component moisture curing / air drying products and two-component reaction hardening (base resin and catalytic hardener) materials, plus both of these types include solvent-free, solvent dispersed and water dispersed products. So even with this one chemistry of Polyurethane technology we have the potential for at least 6 different types of product, even without the other possibilities for product development (polyurethanes are also closely related to polyureas and can be formulated in combination with them to produce some useful protective coatings and bund lining materials – such as the advanced systems from VIP GmbH).
Our specialist team at NCC can cut through the ‘minefield’ of misleading marketing information and provide you with the specific expert advice on all of the different polyurethane and polyurea options and help you to find the right solutions for your specific projects. For assistance please just call any of our offices and our experts will be delighted to help.
Polyurethane (PU) Lining & Coating: One-part Products
In 1 part / one-component / single-pack polyurethane products the catalyst for the material to cure is usually water, water from the atmosphere (as water vapour from the humidity), or water from the substrate. This is the reason that one component polyurethane coatings are described as sensitive to moisture and must be applied on dry substrates. When a damp concrete substrate has to be coated, it is usually first sealed with an epoxy primer and then the surface is allowed to dry before the PU coating application.
One-component water dispersed PU Coating products are not generally of sufficiently high performance and durability for use in anything other than light duty applications (i.e. domestic etc.) and certainly not for any medium to heavy duty commercial and industrial requirements where aggressive chemical and / or trafficking resistance is required. However there are solvented or solvent containing, one-pack polyurethane resin coatings and bund linings that have relatively high performance, but they also have all of the same application difficulties and restrictions for use (Health & Safety, Fire risk etc.) as other solvent containing resin coatings and lining products.
However the one-part, solvented PU coatings can provide very useful protective coatings and bund or linings for domestic and relatively light to medium duty commercial and industrial applications, such as those around limited oil storage, recovery and delivery areas, where their function is secondary containment of any spillages whilst removal and clean-up is arranged. The best example of these on the market is probably the Sikafloor-400 System
NCC do not recommend any one (or two part) solvent containing polyurethane resin systems for use in any internal or below ground bund lining, or containment tank applications. This is because when they are applied there will be VOC’s released into the air that are potentially dangerous to people and the environment, plus they will have restrictions in use, protective clothing and equipment will be required, which will always increase the project costs and at best be very inconvenient to comply with the necessary H&S restrictions, and all for a relatively low performance type of material.
Two-part Polyurethane (PU) Resin Bund Lining & Coating Products
Two-component PU Resin Bund Lining and Protective Coating materials are generally solvent-free, high build coatings which have excellent wear and chemical resistance, together with inherent flexibility and even elasticity, which means that they can be used where defined crack-bridging properties are required from the protective coating system. As they are usually designed to be fast curing (15 to 45 seconds), the products are normally applied with two-component airless spray equipment, where the mixing occurs at the nozzle. This can also be further controlled by using heated airless spray equipment (i.e. from the Graco XP Quick Set Range), and selecting the temperaure that achieves the initial set time that is required i.e. to allow te material to flow into the surface profile, or not to flow down vertical surfaces, all according to the projects specified requirements.
The use of solvent-free materials allows the coating and linings systems to be built-up in thicker layers, requiring the minimum number of applications, without blistering and intercoat delamination due to entrapped water or solvents. Water dispersed 2-part polyurethane products are not recommended for this type of linings and coatings.
The solvent-free two-pack PU linings and coatings usually need pre-treatment of the surface against moisture and ongoing vapour transmission etc., to seal porous concrete or masonry surfaces and also to ensure that the PU coating bonds sufficiently and chemically to the primer on dense substrates – Therefore PU resin Bund Linings and Protective Coatings are usually applied to concrete substrates surfaces that have first been mechanically prepared i.e by blastcleaning; then it is sealed, typically with a clear, penetrative, moisture tolerant, epoxy resin based primer that in this way ensures adhesion of the top coats, and a pinhole-free, polyurethane based, protective top coating or bund lining material.
The specialists at NCC can advise you on the most suitable polyurethane or other resin bund lining or protective coating solution for your specific project needs. Please call any of our offices for assistance from our protective coating and lining experts.
6). Polyurea Bund Lining Systems
Polyurea resins are technically and chemically a type of elastomeric resin derived from the original reaction product of a polyol and an isocyanate component through stepped polymerization. It was only a relatively few years ago in the 1990’s that advanced two-component polyurea based (i.e. VOC-Free Polyaspartic Aliphatic Polurea resin based) bund linings, waterproofing systems and protective coating systems were first introduced. These offered improved application characteristics and cure rates with reduced environmental and handling limitations than some established resin lining and coating materials.
Additionally there were also advantages and increased performance in terms of their mechanical properties and chemical resistance over the more established resin materials, especially for some of the more demanding waterproofing and bund / containment area lining applications. Specifically their fast reaction curing and hardening (significantly better than epoxy resin systems), with relative low sensitivity to moisture (significantly better than polyurethane resin systems), make them very useful protective coatings. They are also normally spray applied, mixed at the nozzle, making them especially for cost effective with this machine application on large surface areas in many bunded and secondary containment areas – such as tank farms and processing / distribution and handling facilities.
Polyurea containment area lining systems have already been used in the USA for over 20 years, where large areas of protective linings and coatings requirements quickly made investment in the expensive spray equipment a good option. In the UK and other European countries, their use and market share is also growing steadily for different industrial and construction waterproofing applications, with related products having already been widely used in this region for truck beds and the like by vehicle manufacturers in their factories and workshops.
Many of the companies that developed these materials in the USA and first introduced them to the UK and Europe , became focussed on these easier and less-demanding, repeat applications that can be carried out in factory controlled conditions rather than on construction sites or industrial plants that are still in operation or where multiple trades are required to work in close proximity. Therefore the majority of their experience is in the comparatively simple coating and lining of steel truck beds and tanks, and also because of Polyurea systems quick curing and inherent flexibility, for the manufacture of bespoke scenery and film studios / film sets also. However we finally found one specialist German Company VIP GmbH., which has focussed more on the site application of these systems and developed their range of products, specifically for this purpose, over the last 10 years. VIP now work with NCC as exclusive distributors of their Polyurea protective coating and bund lining products and their application in the UK.
Polyurea Resin Based Bund Lining Systems
Advantages of Polyurea Resin Lining and Coating Systems
Polyurea Resin Lining and Coating Systems are spray-applied, very fast curing, can be applied in thick layers in one application (usually 1 - 5mm) and is touch dry in 5-10 seconds, allowing complete systems to be installed extremely quickly ensuring a rapid return to service. There are a number of important advantages that can be obtained by using the latest Polyurea Resin linings and coating systems that include:
• High Tensile Strength
• Moisture Tolerance
• Excellent Adhesion
• Environmentally Friendly
• High Abrasion Resistance
• Excellent Heat Resistance
• Rapid curing
• VOC, plasticiser and heavy metal-free
• Extremely durable
Disadvantages and Limitations of Polyurea Systems
Some of the beneficial properties offered by polyurea elastomeric coatings can also pose some issues that may be a disadvantage for some projects such as:
• Application can be nozzle operator dependent and as it is fast this must be monitored closely.
• Fast curing can mean insufficient ‘wetting’ of the substrate if this is not assessed, prepared and where necessary primed correctly to ensure optimum adhesion.
• Although tolerant of damp conditions, polyurea systems should not be applied on ‘wet’ surfaces so again good Quality Control on site must be maintained.
• Polyurea systems require specialist application techniques and the selected contractor must have full training from the manufacturer of the products and the expensive equipment required
• Due to all of the above contraints, limited comparative and competitive pricing can be made, so the correct advice and selection of the right polyurea system and competent specialist contractor is essential.
• Poyurea coatings are designed to be protective rather than aesthetic, so the sprayed finish can have an ‘orange-peel’ effect and in UV light they can discolour – although this does not affect the protective performance.
• Therefore for all of the above advantages and the prevention of any issues on site, getting the right advice and support from the polyurea coating and lining specialists at NCC Bund Lining is also an essential pre-requisite for successful completion and durability of your bund lining and containment projects.
Application Requirements and Characteristics of Polyurea Resins
- As with all resin bases bund lining and protective coating systems, the concrete substrate must be sound and of sufficient compressive strength (minimum 25 MPa), with a minimum pull-off strength of 1.5 N/mm². Any unsound or damaged concrete must be removed and repaired, plus any surface defects such as blowholes and voids must be fully exposed and repaired with suitable compatible products.
NCC Bund Lining can advise on these too and have a large amount of these repair materials in stock at our depots around the country.
- Prior to application of polyurea resin systems the substrate moisture content must be < 4% , the relative humidity should also be checked and recorded, so that dew point conditions can be avoided. If the moisture content is more than > 4%, then application of the polyurea coating can only proceed when the moisture level reaches an acceptable level, or a temporary moisture barrier such as Sika EpoCem technology, is applied and then the work will be able to proceed the next day, once this barrier layer has hardened sufficiently.
- Concrete substrates must be cleaned and then mechanically prepared using abrasive blast cleaning for example, to remove any cement laitance, existing coatings and to achieve a fine gripping profile that is clean, dry and free from laitance, dirt, grease, oil and any other form of surface contamination.
- Polyurea systems require installation by trained and experienced contractors as in the end, the person at the spray gun is mostly responsible for the quality level that is achieved, which is why the whole process must be monitored. The selected contractors operatives must all be adequately trained and instructed in a project specific Quality Control process that will lead to the best possible results.
The specialists at NCC can advise you on the most suitable polyurea resin systems, trained Specialist Contractors (please also see the ‘Specialist Contractors’ Page of this website), for your specific bund lining project needs. Please call any of our offices for assistance from our experts.
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