FLEXCRETE TECHNOLOGIES LTD
Suppliers of: mortars, high performance coatings,
Flexcrete Technologies Ltd is a leading manufacturer of engineering quality concrete repair mortars and high performance coatings. Our products offer high performance, durable and innovative solutions for construction, civil engineering, infrastructure, coastal and utilities projects, amongst many others. Whatever your project, we have the specialist products, expert knowledge and technical back-up to assist.
Flexcrete products are used to solve complex structural problems in some of the world’s most hostile environments, so we ensure they offer ultimate protection against water penetration, chemicals, chloride ions, carbonation and other aggressive forms of attack.
In July 2017, AkzoNobel announced the acquisition of Flexcrete Technologies Ltd in a deal that will further strengthen its global leadership position in innovative coatings for the industrial sector. Flexcrete has worked alongside AkzoNobel for a number of years with outstanding performance, integrity, innovation and sustainability being pillars of our mutual success. We are proud to become part of a portfolio with such well-known brands as Dulux, Sikkens & International.
Flexcrete’s back-up service includes:
• Provision of bespoke technical specifications for each project
• Creation of project-specific CAD detail drawings
• On-site technical service and support
• Application training at our dedicated national training facility
• Continuing Professional Development (CPD) seminars. Click here for more about our presentations.
Flexcrete cover a range of sectors which include but are not limited to:
Whether you are looking for concrete repair, basement waterproofing, concrete waterproofing, concrete bridge repair and maintenance, anti-carbonation protection, fast track flooring solutions, protection of marine and costal structures, new build construction, cementitious coatings for the water indusrty or hygienic coatings for walls and ceilings. you can be rest assured Flexcrete has the solution for you.
Our range of products include:
Professional Support from a Team You Can Trust
Rather than merely supplying materials, we offer product solutions and do all that we can to provide the technical support required to complete projects to the highest possible standards. We have an experienced and dedicated technical support team who offer assistance out in the field and pride ourselves on the quality and speed of response to technical queries, whether these are over the telephone, by e-mail or via our website. Our technical experts provide support on projects all around the world, including both application training and after sales support.
- Provision of bespoke technical specifications for each project
- Expert assistance with materials selection
- Creation of project-specific CAD detail drawings
- On-site technical service and support
- Expert advice on meeting relevant regulations and legislation
- Contractor training at our dedicated national training facility
- Application training out in the field
Quality Assurance and Accreditations:
With major investment made in testing and quality assurance programmes, you can be confident that Flexcrete materials will stand up to the highest scrutiny.
Manufactured under quality management systems certified to ISO 9001, Flexcrete products benefit from CE marking in full compliance with BS EN 1504, the pan European standard for the protection and repair of concrete structures. Many of our products are also independently certified by the British Board of Agrément (BBA) and are approved for use in contact with drinking water. In addition, we offer a full range of products approved to London Underground Standard 1-085 ‘Fire Safety Performance of Materials’. As Flexcrete is also successfully accredited to both ISO 14001 (Environmental) and OHSAS 18001 (Occupational Health and Safety), our customers can have complete confidence that we have an ongoing commitment to improving quality, environmental and health and safety performance.
CAD drawings available here
CPD’s are now availabe: Book a Flexcrete CPD Presentation and find out more about our Concrete Repair & Protection Products and discover how our industry leading technology could benefit your next project.
Further technical information is available on the BPi download Library or on the Flexcrete Website.
These files are provided by the manufacturer. While Building Products Index takes every care to ensure the information is correct and up to date, we cannot be held liable for any out of date or incorrect information in them. Please check with the supplier before specifying or purchasing products.
1. Flexcrete Technologies Brochure
mortars and high performance coatings
Published [24/06/19]File size [11567 KB]
2. Flexcrete Solutions for Buildings (Concrete Repair & Protection)
Flexcrete's concrete repair and protection solutions for commercial buildings.
Published [26/05/17]File size [2720 KB]
3. Flexcrete Solutions for Infrastructure (Concrete Repair & Protection)
Flexcrete's concrete repair and protection solutions for civil engineering & infrastructure
Published [26/05/17]File size [2847 KB]
4. Flexcrete Solutions for the Clean Water Industry
Flexcrete's concrete repair and protection solutions for clean water structures.
Published [26/05/17]File size [2459 KB]
5. Flexcrete Solutions for the Dirty Water Industry
Flexcrete's concrete repair and protection solutions for dirty water structures.
Published [26/05/17]File size [2066 KB]
6. Flexcrete Solutions for Coastal Engineering
Flexcrete's concrete repair and protection solutions for coastal and marine structures.
Published [26/05/17]File size [1724 KB]
7. Flexcrete Solutions for Concrete Weatherproofing
Flexcrete's repair and protection solutions for concrete structures.
Published [26/05/17]File size [2912 KB]
8. Flexcrete Solutions for Floors & Trafficked Areas
Flexcrete's repair and protection solutions for concrete floors and trafficked areas.
Published [26/05/17]File size [2160 KB]
9. Flexcrete Solutions for Hygiene
Flexcrete's high performance coatings for hygiene sensitive environments.
Published [26/05/17]File size [1594 KB]
a. Flexcrete Solutions for New Build
Flexcrete's concrete repair and protection solutions for new build construction.
Published [26/05/17]File size [2664 KB]
b. Flexcrete Solutions for Roofing
Flexcrete's repair and protection systems for roofs.
Published [26/05/17]File size [2424 KB]
c. Flexcrete Solutions for Motorways & Highways Structures
Flexcrete's repair and protection solutions for SMART motorways, bridges and concrete highways structures.
Published [26/05/17]File size [2024 KB]
d. Flexcrete Solutions for Strutural Waterproofing
Flexcrete's concrete repair and protection solutions for structural waterproofing applications.
Published [26/05/17]File size [3119 KB]
Flexcrete Basement Waterproofing System Leaflet 2017
Published [19/05/17]File size [995 KB]
Flexcrete Biodex HB Product Data Sheet Jan 2017
Elastomeric, Water-Based, High Build Biostatic Coating
Published [18/05/17]File size [513 KB]
Flexcrete Biodex Sheen Product Data Sheet Jan 2017
Elastomeric, Water-Based Biostatic Coating
Published [19/05/17]File size [510 KB]
Flexcrete Biodex Wash Product Data Sheet Jan 2017
Surface Treatment for Neutralising Active Mould, Fungal & Bacterial Growth
Published [29/05/17]File size [448 KB]
Flexcrete Bond Prime Product Data Sheet Jan 2017
Primer to Seal and Stabilise Substrates
Published [19/05/17]File size [483 KB]
Flexcrete Bonding Bridge 842 Product Data Sheet Jan 2017
Bonding Agent for High Porosity Concrete
Published [24/06/19]File size [479 KB]
Flexcrete Cementitious Coating 851
Surface Protection System - Protection against Ingress
Published [25/05/17]File size [508 KB]
Flexcrete Cemprotec 2000-S Product Data Sheet Jan 2017
Flexible Waterproof Sealing Tape
Published [19/05/17]File size [728 KB]
Flexcrete Cemprotec E Floor HB Product Data Sheet July 2018
Epoxy and Polymer Modified Cementitious Flooring System: 3-6mm
Published [25/06/19]File size [497 KB]
Flexcrete Cemprotec E Floor Product Data Sheet July 2018
Published [25/06/19]File size [496 KB]
Flexcrete Cemprotec E942 Product Data Sheet Jan 2017
Cementitious Coating for Concrete and Steel
Published [29/05/17]File size [500 KB]
Flexcrete Cemprotec Edge Scrim Product Data Sheet Jan 2017
Glass Fibre Reinforcement for Cementitious Systems
Published [19/05/17]File size [351 KB]
Flexcrete Cemprotec EF Primer Product Data Sheet Jan 2017
Stabilises and Seals Cementitious & Asphalt Substrates
Published [25/06/19]File size [481 KB]
Flexcrete Cemprotec Elastic 3 PDS Feb 2018
Elastomeric Cementitious Flexible Coating
Published [25/06/19]File size [501 KB]
Flexcrete Cemprotec Flex-Tape Product Data Sheet Jan 2017
Multi-Directional Reinforcing Tape for Cracks and Joints
Published [29/05/17]File size [466 KB]
Flexcrete Cemprotec Geo80 Product Data Sheet Jan 2017
General Reinforcement for Elastomeric Cementitious Coatings
Published [29/05/17]File size [370 KB]
Flexcrete Cemprotec GFM Product Data Sheet Jan 2017
Special Glass Fibre Reinforcement for Flexcrete Membranes
Published [29/05/17]File size [542 KB]
Flexcrete Cemprotec Levelling Coat Product Data Sheet Jan 2017
Self-Levelling Cementitious Coating / Wearing Screed for Concrete Floors
Published [29/05/17]File size [510 KB]
Flexcrete Cemprotec MCI 2020 Product Data Sheet Jan 2017
Surface Applied Corrosion Inhibitor
Published [29/05/17]File size [369 KB]
Flexcrete Cemprotec Sandseal 75 Product Data Sheet Jan 2017
Clear Lacquer for Concrete Floors
Published [25/06/19]File size [555 KB]
Flexcrete Cemprotec Sandseal WB Product Data Sheet Jan 2017
Low Odour Clear Sealer for Concrete Floors
Published [25/06/19]File size [553 KB]
Flexcrete Cemprotec Sandseal WB Product Data Sheet Jan 2017
Low Odour Clear Sealer for Concrete Floors
Published [29/05/17]File size [559 KB]
Flexcrete Colour Chart 2015 A5
Published [24/06/19]File size [1846 KB]
Flexcrete Fastfill WP Product Data Sheet Jan 2017
Rapid Setting Water Plugging Mortar
Published [24/06/19]File size [349 KB]
Flexcrete Marine Mortar S Product Data Sheet Jan 2017
Class R4 Structural Repair Mortar for Marine and Tidal Areas
Published [19/05/17]File size [498 KB]
Flexcrete Metal Prime WB Product Data Sheet Jan 2017
Waterborne Anti-Corrosive Primer for Metal Substrates
Published [29/05/17]File size [505 KB]
Flexcrete Monodex Clear Product Data Sheet June 2017
Clear, Water-Based, Anti-Carbonation Coating
Published [24/06/19]File size [515 KB]
Flexcrete Monodex ICB Product Data Sheet Jan 2017
Intermediate Crack Bridging Filler and Coating
Published [29/05/17]File size [326 KB]
Flexcrete Monodex Metallic Product Data Sheet Jan 2017
Translucent Metallic, Water-based Anti-Carbonation Coating
Published [29/05/17]File size [366 KB]
Flexcrete Monodex Smooth Product Data Sheet March 2018
Elastomeric, Water-Based, Decorative Anti-Carbonation Coating
Published [24/06/19]File size [403 KB]
Flexcrete Monodex Textured Product Data Sheet Jan 2017
High Performance, Flexible, Waterborne Textured Wall Coating
Published [19/05/17]File size [487 KB]
Flexcrete Monodex Ultra Product Data Sheet Jan 2017
Water-Based, Flexible Decorative Coating
Published [29/05/17]File size [515 KB]
Flexcrete Monodex UVC Product Data Sheet Jan 2017
Highly Elastomeric UV Cured Waterborne Coating
Published [29/05/17]File size [370 KB]
Flexcrete Monolevel 250F Product Data Sheet Jan 2017
Class R1 Fine Grade Fairing Coat for Existing Paint Finishes
Published [19/05/17]File size [485 KB]
Flexcrete Monolevel 844SP Product Data Sheet Feb 2018
Class R4 Waterproof Screed and Pore Filler
Published [24/06/19]File size [496 KB]
Flexcrete Monolevel FC Product Data Sheet Jan 2017
Fairing Coat and Thin Screed Render
Published [29/05/17]File size [497 KB]
Flexcrete Monolevel RM Product Data Sheet Jan 2017
Fibre Reinforced, Waterproof, One-Coat Cementitious Render
Published [29/05/17]File size [497 KB]
Flexcrete Monolite Product Data Sheet Jan 2017
Class R2 Lightweight Repair Mortar
Published [19/05/17]File size [492 KB]
Flexcrete Monomix HD Product Data Sheet Feb 2018
Class R4 High Strength Structural Repair Mortar
Published [24/06/19]File size [545 KB]
Flexcrete Monomix Product Data Sheet Jan 2017
Class R3 General Purpose Structural Repair Mortar
Published [19/05/17]File size [501 KB]
Flexcrete Monomix WS Product Data Sheet Jan 2017
Class R3 General Purpose Spray Applied Repair Mortar
Published [29/05/17]File size [538 KB]
Flexcrete Monopour Product Data Sheet Jan 2017
Pourable Repair Mortar
Published [19/05/17]File size [484 KB]
Flexcrete Monorub Product Data Sheet
Class R1 Fine Grade Fairing Coat
Published [19/05/17]File size [385 KB]
Flexcrete Monosil Product Data Sheet Jan 2017
Clear Hydrophobic Impregnant for Water and Oil Repellency. Impregnation Treatments.
Published [19/05/17]File size [461 KB]
Flexcrete PDS Fastfill Structural Repair Mortar July 2018
Class R4 Rapid Setting Structural Repair Mortar
Published [24/06/19]File size [184 KB]
Flexcrete Polymer Admixture 850 Product Data Sheet Jan 2017
Sealer and Bonding Agent for Polymer Mortars, Renders and Screeds
Published [19/05/17]File size [482 KB]
Flexcrete Roofdex HB Product Data Sheet March 2018
High Build, Eco-Friendly, Cold Applied Liquid Roofing
Published [25/06/19]File size [497 KB]
Flexcrete Steel Reinforcement Protector 841 Product Data Sheet Jan 2017
Reinforcement Corrosion Protection
Published [19/05/17]File size [494 KB]
Flexcrete Tiefill Product Data Sheet Sept 2018
Class R4 Waterproof Tiehole Filler
Published [24/06/19]File size [166 KB]
Flexcrete Unimatch Product Data Sheet Jan 2017
Class R1, Colour Matched, Rapid Setting Cosmetic Repair Mortar
Published [24/06/19]File size [506 KB]
Major Upgrade of Eastbourne Wastewater Treatment Works
A major £16 million upgrade of Eastbourne Wastewater Treatment Works is currently being carried out on behalf of Southern Water and part of the works has comprised the refurbishment of an underground reinforced concrete inlet chamber at the plant.
Dating back to 1997, Eastbourne Wastewater Treatment Works is located on a prime site on the seafront at Langney Point in East Sussex. Serving a population of circa 140,000 people across the Eastbourne area, the vast majority of the works is located underground, beneath a fortress-style building. Up to 74 million litres of wastewater is pumped into the works every day and treated almost entirely out of sight.
The concrete repair work was carried out by specialist asset maintenance contractor Concrete Repairs Limited (CRL) beneath ground level in confined spaces and extremely arduous conditions. The project involved the repair and refurbishment of the underground inlet channel that receives wastewater flows, as the concrete had deteriorated due to attack from hydrogen sulphide (H2S) gas and sulfuric acid. The project was carried out on behalf of CMDP, a joint venture between Costain and MWH and one of Southern Water’s three business partners delivering AMP6 improvements until 2020.
The original specification called for the use of a dry-spray repair mortar, a levelling skim coat and a final layer of a high-performance cementitious coating. However, in order to increase productivity and project efficiency, as well as shorten the programme time, it was decided to use a two-product system comprising Intercrete concrete repair materials to refurbish the underground inlet chamber. Intercrete is part of the International brand, expanded following AkzoNobel’s acquisition of Flexcrete Technologies in July 2017, with Flexcrete products now known as Intercrete.
A system was specifically devised comprising a dry spray application of Intercrete 4801 repair mortar followed by a final coat of 4840 cementitious coating. By using 4801 as a spray mortar, CRL were able to do away with the skim coat due to the exceptional finish on the 4840. This meant that the skimming stage was no longer required and there were no compatibility issues as the 4840 cementitious coating could be applied directly onto the rapid curing 4801.
In order to remove the defective concrete first, CRL used hydro-demolition methods before the dry-spray application of 4801. The Intercrete application was then carried out at night when flows were lowest and in total, almost 140 tonnes of 4801 was applied over a six-month period by CRL.
4801 is a high-strength, waterproof, shrinkage compensated, class R4 cementitious repair mortar, which exhibits extremely low rebound when applied either by dry- or wet-spray techniques for the structural repair,rendering and profiling of vertical, overhead and horizontal surfaces. The dry-spray application was particularly well suited for use at Eastbourne due to the low rebound/waste in the confined area, allowing easier site clean-up and a safer working environment.
Supplied as a single component system only requiring the addition of clean water on-site, 4801 incorporates advanced cement chemistry, silica fume, fibre and styrene acrylic copolymer technology. CE marked in accordance with BS EN 1504 Part 3(1), it can be applied up to 80mm in a single layer and rapidly develops a high bond strength exceeding the tensile strength of concrete, thus ensuring monolithic performance of the repair. Developing a compressive strength of 33MPa within just 24 hours, one of the key advantages for this project was its rapid curing time, meaning it could be overcoated with 4840 within hours rather than days. It also has excellent sulfate resistance remaining resistant to sulfates to class DS-5/5m of BRE Special Digest 1(2).
Once the 4801 had fully cured, 4840 was applied. This is a two-component, water-based cementitious coating that benefits from modification with both a thermoplastic polymer as well as an epoxy resin to provide a hard wearing surface with greatly enhanced chemical and abrasion resistance.
This combined 4801/4840 system was also specified for another Southern Water project carried out by CRL at Ford Wastewater Treatment Works in Arundel. For both projects the combined 4801/4840 was chosen on the basis of its rapid curing properties, the omission of the skim coat due to the high-quality finish of the mortar and the short period between the application of the mortar and coating.
The finished system exhibits high chemical resistance in aggressive wastewater facilities, with no concerns about application in a damp environment and the ability to clean down works on a live waste site with storm flows. The system also minimises environmental impact due to the fact that both products are water-based, ultra-low odour and solvent-free, making them safe to apply in confined spaces and even while facilities are in operation.
The £16 million overhaul of Eastbourne Wastewater Treatment Works will bring many long-term benefits and ensure wastewater leaving the site is of the highest quality. As well as the concrete repair work, other upgrades include updating the biological filter, improving lighting, ventilation and odour controls and replacing pumps and other equipment. The refurbishment is due to be fully completed during early 2020.
Chemical Attack & Cementitious Coatings for Concrete Repair & Protection
Concrete deterioration exists on a global scale and can severely affect the durability of reinforced concrete structures. The primary causes of chemical attack on concrete include chloride ion penetration, sulphate attack and carbonation, but technical advances in cementitious coating technology have allowed extended service life solutions to be implemented.
A major cause of damage to reinforced concrete exposed to chlorides is corrosion of the steel reinforcement, especially for structures in marine, highway and other chloride-laden environments, including buildings in proximity to the coastline. Chloride ion penetration leads to the aggressive corrosion of steel reinforcement, even in alkaline concrete, causing cracking and spalling, and in the very worst cases structural failure.
Steel reinforcement is protected against corrosion by the inherent highly alkaline environment of the concrete created by the generation of calcium hydroxide from the cement hydration. This results in the formation of a passivating layer of ferric oxide on the embedded steel. As long as this surface film is maintained, the steel remains protected from corrosion.
However, when concrete structures are repeatedly exposed to airborne chlorides or salt spray, due to their minute size, chloride ions penetrate the pores of the concrete, eventually reaching the steel, breaking down this layer and causing corrosion. In the case of marine structures, corrosion most rapidly occurs in the splash zone where the intermittently wet and dry conditions exacerbate the penetration of chlorides and there is enough oxygen to facilitate the corrosion process. There is also sufficient moisture present to increase the electrical conductivity of the concrete, leading to an aggressive form of localised attack called pitting corrosion; this can potentially cause rapid loss of steel section and major cracking and spalling of concrete, thereby compromising structural integrity.
In tidal and submerged zones where the concrete is saturated in seawater and oxygen levels are limited, the pore structure is constantly filled with water. Nevertheless, in areas where there is low concrete cover, corrosion can still occur, causing a challenge for its reinstatement. The depth and quality of the cover concrete is vital, as the relatively thin layer of concrete protects the reinforcing steel from corrosion by maintaining an alkaline environment and preventing the ingress of chloride ions and the other fuels for corrosion. This is recognised in European Standards with EN 206 defining the concrete mix design and EN 10080 giving the requirements for cover.
Whilst marine structures are subject to constant exposure to chlorides, highway structures are similarly affected during the winter periods when de-icing salts are used. These readily dissolve in snow or rain water and the resultant highly concentrated salt solution or spray from vehicles can pose a threat to concrete structure within the vicinity of a highway with the potential for chloride ion ingress, exacerbated by repeated wetting and drying cycles.
As soon as low concrete cover has been identified, it is important to take swift action, otherwise the lack of protection to the re-bars will lead to premature de-passivation of the steel and subsequent corrosion. Inadequate concrete cover will not only speed up the damaging effects of carbonation but also allow even more rapid ingress of chlorides, moisture and oxygen. At worst, sections of concrete may need to be demolished, or partial recasting may need to be carried out, however both these options are very costly and often difficult to carry out
In terms of reinforced concrete in waste water facilities, the most widely feared mechanism for the erosion of concrete in sewerage systems is bacterial in origin. Normal domestic sewage is slightly alkaline and does not contain sulphates in sufficient concentrations to attack concrete directly. The damage which occurs is due to sulphuric acid produced by certain bacteria as a result of changes occurring in sewage.
When conditions are such that oxygen in the sewage becomes depleted, anaerobic organisms, which do not use atmospheric oxygen, obtain their requirements for growth from salts. This also has the effect of reducing sulphates and other organic sulphur compounds in the sewage to form hydrogen sulphide.
Contrary to popular belief, the gas itself does not directly attack concrete, but it will readily dissolve in moisture particularly on the crown or soffit of sewers and on the walls above liquid level and is then oxidised to sulphuric acid by aerobic organisms of the Thiobacillusspecies. Research conducted in the USA indicates the concentration of sulphuric acid generated within sewerage systems peaks at circa 5%, which readily attacks normal concrete. There are various factors which determine the precise concentration but high temperatures are known to greatly encourage bacterial growth.
Soft Water Attack
Soft water is defined as water deficient in calcium and magnesium salts and can be a major problem in reservoirs storing high moorland or mountain water. Because of its pure nature, it effectively acts as a high performance solvent, dissolving the lime that is formed either as a by-product of the cement hydration process or is present in limestone aggregates to result in deterioration of the concrete.
Some soft waters also contain aggressive dissolved carbon dioxide which produces weak carbonic acid. Other organic acids naturally occur in soil and ground waters from rotting vegetation such as humic acid which originates from peat. These reduce the pH to below 5.0, thus making the water highly aggressive and undermining the integrity of concrete by weakening the matrix. With increased permeability, the concrete is vulnerable to advancing deterioration as the pore structure is opened to more acid ingress, ultimately resulting in breakdown of the substrate and failure of the structure to contain water.
There are cementitious coatings available that exhibit excellent resistance to attack from soft water. Key products incorporate pozzolanic materials and microsilica. Pozzolans react with the lime to form high levels of insoluble calcium silicate hydrates with very good chemical resistance. Microsilica effectively ‘mops up’ lime and affords enhanced resistance to chemical attack. Furthermore, the polymers incorporated into these materials form a protective film on the surfaces of the hydrates, subsequently enhancing the chemical resistance even further. Key products can also withstand immersed conditions without detrimental effect and have been specified for many contracts where water authorities have experienced specific problems with soft water attack.
As an example, cementitious coatings were used to repair over 30 reservoirs as part of the Northern Ireland Framework Rehabilitation Programme. Virtually all of the structures were suffering from soft water attack and in some cases, the attack was so severe that repair mortars were first used to reinstate the integrity of the substrate before a protective coating could be applied.
Carbonation, which is the breakdown of the alkaline environment surrounding steel reinforcement, is another major problem in untreated concrete infrastructure exposed to atmosphere. Carbon dioxide migrates through cracks and pores in concrete, reducing the pH of the alkaline environment from 12-13 to around 9, inevitably leading to corrosion and concrete spalling. The carbonation of concrete is one of the main reasons for corrosion of reinforcement.
As detailed in an earlier paragraph, reinforced concrete buildings and other assets suffer from exposure to airborne chlorides in coastal environments. Without suitable protection from the elements, carbonation and chloride ingress combine to form a dangerous cocktail which, in addition to the effects of weathering, can soon impact on durability and the intended design life.
Protective Coating Technology
In the last 30 years, major technical advances have taken place in protective coating technology. Significant progress has been made by certain manufacturers of decorative anti-carbonation coatings to offer high levels of performance with a paint film thickness that would not have been possible even just 10 years ago. In the field of engineered protection for heavy duty applications, the latest cementitious coatings have allowed extended service life solutions to be implemented in conditions which are impractical for traditional alternatives.
Exposed steelwork after hydrodemolition
The latest generation cementitious coatings will overcome many of the limitations of resin systems and can be applied to damp substrates without risk of osmotic blistering. Offering high resistance to wash-out, they withstand immersion as little as 60 minutes after placing. Their high build application and rapid cure makes them less susceptible to damage, especially during their early life. Furthermore, as water-based systems, the environmental credentials are attractive, posing minimal risk in application with all equipment being washed in water after use. Testing on structures suffering from carbonation which have been treated with such cementitious coatings shows that the concrete will realkalise and the depth of carbonation is reduced to afford further protection to the reinforcement, particularly in the presence of chlorides.
Cementitious coatings can be directly applied to reinforced concrete structures which are either approaching the end of their design life or which have suffered from premature degradation. These high performance coatings can also be used on new build structures as part of the original design or to provide a solution to non-conformance with specification. Where critical structures such as bridges are being built in onerous marine environments, consultants recognise the benefits of such coatings to help ensure the 120 year design life is achieved without the risk of costly future maintenance.
With regards to repair projects, defective concrete can be cut out and the steel reinforcement can be protected with a corrosion preventative, flexible coating to protect the steel prior to the application of concrete repair mortars and protective coatings.
One product which is frequently specified on both existing and new structures to waterproof, reinstate cover and provide an effective barrier to chloride ingress is Intercrete 4841, formerly known as Flexcrete’s Cementitious Coating 851. Intercrete 4841 is a highly advanced, two component, waterborne cementitious modified polymer coating which was originally introduced in 1985, and it still remains one of the most effective products for providing structural protection against chloride attack. A 2mm coating of Intercrete 4841 is equivalent to 100mm of good quality concrete cover.
Independent testing carried out at the VINCI Construction Technology Centre in Bedfordshire has officially confirmed that Intercrete 4841 provides an effective barrier against chlorides lasting at least 30 years. In 1988, a 2mm thick film of Intercrete 4841 was applied to a concrete slice and sealed in a chloride ion diffusion cell, and 30 years (10,950 days) later it is still providing full protection. Continuous tests carried out in the VINCI Construction Technology Centre laboratory show that the barrier properties of Intercrete 4841 have remained the same throughout the test period, a testament to product’s consistent and long-lasting performance.
Many coating systems degrade over time when on test in the cell, and even products that initially perform well can subsequently blister, resulting in more chloride ions passing through the product. Intercrete 4841 has not shown any signs of deterioration despite being fully immersed in the chloride solution for 30 years. It would have taken 271 years for the product cell with the Intercrete 4841 to reach the same chloride concentration that the uncoated specimen reached in just 98 days.
Intercrete 4841 is widely specified on both existing and new structures in coastal environments, highways and the water and wastewater industry. It can also provide an alternative to the recasting or demolition of precast and in-situ reinforced concrete, reinforcing the substrate with the durability to achieve its specified design life.
Cases in Action
As part of a major £16 million upgrade of Eastbourne Wastewater Treatment Works, Intercrete concrete repair materials were chosen to refurbish an underground inlet chamber at the plant. Almost 140 tonnes of Intercrete 4801 was applied over a six month period by specialist asset maintenance contractor, Concrete Repairs Limited.
Dating back to 1997, Eastbourne Wastewater Treatment Works is located on the seafront at Langney Point in East Sussex. Serving a population of circa 140,000 people across the Eastbourne area, the vast majority of the works is located underground, beneath a fortress-style building. Up to 74 million litres of wastewater is pumped in and treated every day almost entirely out of sight.
The concrete repair work was carried out beneath ground level in extremely arduous conditions. The project involved the refurbishment of the underground inlet channel that receives wastewater flows, as the concrete had deteriorated due to attack from hydrogen sulphide (H2S) gas and sulphuric acid. The Intercrete application was carried out at night when flows were low.
An Intercrete system was devised for the project comprising a dry spray application of Intercrete 4801 repair mortar followed by a final coat of Intercrete 4840 cementitious coating. The system minimises environmental impact due to the fact that both products are water-based, ultra-low odour and solvent-free, making them safe to apply even whilst facilities are in operation.
Concrete Repairs Limited used hydro demolition methods before a dry spray application of Intercrete 4801 – a high strength, waterproof, class R4 mortar which exhibits extremely low rebound when applied either by dry or wet spray techniques for the structural repair, rendering and profiling of vertical, overhead and horizontal surfaces. Following the application of Intercrete 4801, Intercrete 4840 cementitious coating was applied. This combined Intercrete 4801/4840 system was chosen on the basis of the rapid curing properties and speed of reinstatement between application of the mortar and coating as there is no need for a skim coat due to the high quality finish of the mortar.
In another example, Doha Corniche is a waterfront promenade extending for 10km along Doha Bay in the capital city of Qatar, Doha. Formed following extensive dredging work carried out during the late 1970s and early 1980s which reshaped Doha’s coastline, the Corniche is now popular among walkers, bikers and joggers. Protection from high seas is provided by a concrete breakwater which suffers from erosion from wave action and chloride induced corrosion of the steel reinforcement.
When a new 500 metre precast concrete extension was constructed, the use of a chloride barrier was stipulated to extend the design life. Following consideration of a number of coating systems and intense testing, guided by Halcrow International and Partners (now Jacobs), the Ministry of Municipal Affairs and Agriculture (MMAA) specified a 2mm layer of Intercrete 4841. Applied in just two coats by spray equipment and bonding intimately to the concrete, Intercrete 4841 provided a durable waterproof layer which will not break down under the harsh direct sunlight.
In a further project illustrating the effectiveness of protective coatings to withstand sulphate and chloride contaminated ground conditions, over 400 tonnes of Intercrete 4841 was applied to the sub-structure reinforced concrete foundations to assure durability in aggressive ground conditions at the Q-Chem II Ethylene Derivatives Plant in Qatar. The installation of the protective coating was undertaken by Daewoo Engineering & Construction, the main contractor on this US$2bn project. The application was undertaken in compliance with a specification drawn up by Tecnimont S.p.A. of Italy on behalf of the joint venture owners, Qatar Petroleum and Conoco Phillips.