Concrete Repair and Protection

Transcription

1 Concrete Repair and Protection with Remmers Systems Cleaning Equipment Cleaning Chemicals Corrosion Inhibitors Repair and Re-profiling Mortars Protective Impregnations and Coatings

2 Repair and Protection of Concrete and Facades with Remmers Syste Technology and Experience Remmers are world technology leaders in the development and production of specialist systems for the restoration of all types of structure and facades. Remmers extensive global experience includes refurbishment works on thousands of buildings and civil engineering structures, constructed in natural stone, brickwork, timber and the most universal material of today reinforced concrete. Remmers System Approach to restoration with innovative materials for concrete repair and its protection, even in exposed and aggressive environments, is the cornerstone and basis of our success. This is to the benefit of our customers and clients, in the UK and Ireland, throughout Europe and increasingly now worldwide. The successful repair and protection of concrete requires a professional assessment of the type, extent and implications of damage, or the deteriorated aspects of a structure. This assessment must be made by suitably qualified and experienced people to identify the root causes of the damage. This can include mechanical (ie, impact and abrasion), chemical (ie, alkali-aggregate) and physical (ie, the concrete from its surface or by the ingress of corrosive contaminants such as chlorides from marine exposure or the use of de-icing salts. Carbonation is a completely normal and natural process which actually hardens the surface of concrete, as carbon dioxide from the atmosphere reacts with calcium hydroxide (lime) in the alkaline concrete pore water, producing insoluble cubic calcium carbonate crystals, which are deposited, strengthening the matrix. 2 freeze thaw, thermal movement), plus concrete damage due to reinforcement corrosion. Reinforcement corrosion is predominantly preceded by atmospheric carbonation of Unfortunately this process also reduces the passifying alkalinity of the concrete which means that the embedded steel reinforcement is no longer protected. This can then corrode

3 ms Structures in the presence of water and oxygen. The rust products that result are expansive and this expansion within the concrete exerts stresses which result firstly in cracking, which allows more water ingress, and then spalling of the concrete over the corroding reinforcement steel. Chloride attack is usually from sodium chloride (common salt), which is naturally present in sea water and marine atmospheres, or used on highways and parking structures as de-icing salts. Chlorides accelerate steel corrosion processes from what ever their original source. This is because at a concentration of only around 0.3% by weight of the cement content, they actively break down the protective passive oxide layer on the embedded steel surface which was originally produced by the passivating alkaline pore water. Water and chlorides are particularly damaging to reinforced concrete because they also accelerate freeze thaw reactions in low temperatures, which causes additional physical cracking and spalling deterioration of concrete surfaces. A professional assessment of the existing damage must be completed, including a full surface inspection where practical, and diagnostic laboratory analysis where necessary. Then the client s future requirements for the structure are considered in order to determine the most appropriate repair and future protection strategy. Remmers has a truly systematic approach and procedure with specialised solutions for each stage of the process. Successful concrete repair and protection also requires the works to be carried out by suitably experienced contractors. These are able to take advantage of the in-house technical and practical courses provided regularly by Remmers in our corporate training facilities at Loeningen in Germany and at our Sussex headquarters in the UK. 3

4 Repair and Protection of Concrete and Facades with Remmers Syste The Remmers System Approach Condition Survey To identify the type, extent and implications of damage, with diagnostic laboratory analysis where required to select the correct repair and protection system. Cleaning By use of the most appropriate mechanical equipment and chemical cleaning solutions including additional post cleaning inspection to locate any hidden damage. Damage Removal Mechanical break out and removal of the damaged areas, with minimal additional stress to the structure. Corrosion Inhibition Application of corrosion inhibitor solutions, where appropriate, to reduce the risk or rate of future reinforcing steel corrosion. Repair and Re-profiling Replacement of the damaged areas, levelling of the concrete surfaces and restoration of the original profiles with mortar systems. Protective Impregnation and Coating Application of a waterproofing and/or an anti carbonation impregnation or coating system to provide long term protection. 4

5 ms Structures To carry out and complete a successful concrete repair and protection project our system approach can utilise many unique Remmers innovative technologies, equipment and materials. Condition Survey The professional assessment of a deteriorated concrete structure is a pre-requisite for a successful repair project. This includes a full visual survey of the concrete surface and identification of all damaged areas, i.e. concrete defects, cracks, surface deposits (dirt and pollution etc.), the direct exposure and usage of the structure. This is combined with a structural survey to ensure integrity of the different elements or components, and of the structure as a whole. A fully representative cover meter survey is undertaken to confirm the location of the reinforcing steel and the depth of carbonation is measured again this is done for all of the different components and aspects of the structure. Laboratory analysis of samples for chlorides or other chemical contaminants, such as sulphates from industrial pollution, is also used when relevant. From the combination of these results, the clients requirements and of course the budget, the optimum repair and protection strategy can be determined and specified. Remmers provide fully detailed documentary procedures to support the client, the specifier and the contractor to achieve this. Cleaning Once the overall Condition Survey is complete, the most suitable system for cleaning the surfaces can be agreed. The cleaning of concrete surfaces also generally improves the appearance, by removing surface deposits of dirt, carbon and organic growths. However cleaning operations can often reveal additional faults, such as previously hidden cracks, deteriorated joints or other defects, and these must be referred to the responsible engineer for assessment prior to the restoration procedure. Remmers is unique in producing a full range of both sophisticated mechanical cleaning and preparation equipment and chemical cleaning solutions. This means that the engineer and contractor can select and combine the best techniques to produce the optimum system for each project. Therefore Remmers will always obtain the desired results on site. 5

6 Repair and Protection of Concrete and Facades with Remmers Syste Cleaning (continued) Remmers state of the art Rotec whirljet low pressure, rotary cleaning equipment is the most controllable and adaptable on the market. Rotec uses a range of special microfine glass powder abrasives in different granulations which can be used dry or with water. The desired cleaning objectives can be achieved with minimal damage to sound concrete or adjacent surfaces. Conventional vacuum or open blastcleaning and high pressure water jetting can seriously harm concrete surfaces. These also then need to be restored and re-profiled, thereby adding considerably to the cost! Rotec equipment is also used extensively to clean natural stone and brickwork even polished and finely honed surfaces, as well as for graffiti removal on many different substrates. Remmers chemical cleaning solutions include Alkutex and Intachem products based on advanced formulations of:- Aqueous alkalis for dirt and pollutant removal. Solvents for paint and graffiti removal. Aqueous acidic for pollutant and dirt or mortar removal on non cementitious and non calcareous surfaces of natural stone and brickwork. Remmers Chemical Cleaning Solutions Alkutex : Alkaline cleaners for concrete, stone and masonry with special solutions for removing cement laitance from concrete, efflorescence from brickwork plus oil, grease and traffic film from many substrates. Intachem : Alkaline and solvent based cleaners for heavily soiled concrete or stonework including special cleaning solutions for coloured concrete and stone surfaces. Damage Removal Following thorough cleaning, all damaged areas identified by the engineer are mechanically broken out, using only new and sharp chisels. This is to minimise further damage to the structure. Any actively corroding steel reinforcement 6

7 ms Structures Damage Removal (continued) is fully exposed along its corroding length, and all visible rust corrosion products must be removed. Remmers Rotec equipment is particularly efficient in cleaning exposed steel reinforcement due to its highly directional and controlled performance. The areas to be repaired must be cut out according to the type and grade of repair mortar to be used; Remmers Betofix Mortars do not require additional costly angle cuts, and they can also be feather edged another Remmers innovation in concrete repair technology! Corrosion Inhibition Remmers include corrosion inhibiting solutions into the system approach to protect against the development of latent damage. Dependent on the nature and extent of reinforcing steel corrosion, the use of a corrosion inhibitor can reduce the extent of concrete break out and provide additional protection against future corrosion. It is particularly useful against residual chlorides and in preventing incipient anode formation. Remmers Corrosion Inhibitors produce a protective film around the reinforcement even in carbonated or low level chloride containing concrete, ie, where the passive oxide layer has broken down, but damaging expansive rust has not yet formed. Thus the inhibitor extends the time to the onset, or reduces the rate of corrosion, thereby extending the life of the repairs and therefore also of the structure. Repair and Re-profiling Remmers provide a full range of protective anti corrosive primers for exposed steel reinforcement. Remmers repair mortars are used with varying strengths and granulometry to match the requirements of the original structure, and to replace the damaged areas. These are followed by Remmers levelling, pore filling and re-profiling mortars to provide a uniform surface suitable for application of a protective coating, and to restore the original profiles. These advanced Remmers systems are available in grades that are even suitable for fine textured fair faced and 7

8 Repair and Protection of Concrete Structures and Facades with Remmers Systems Repair and Re-profiling (continued) architectural design details (such as textured surfaces, rope or mosaic finishes etc). Remmers use predominantly cementitious, one component mortars for repair and re-profiling works. These use the latest polymer technologies with negligible shrinkage, and include lightweight grades for overhead repair works. Remmers also developed the innovative Betofix system which can be feather edged, to provide cost effective patch repairs in a single application on a single day and without additional expensive angle cuts in preparation, saving time, reducing waste and saving money. All of these proven advantages combine in the Remmers system approach. Protective Impregnations and Coatings Following the repair and re-profiling of damaged concrete areas, a protective impregnation and/or protective coating is applied to prevent future water and chloride ingress and to provide a barrier against future carbonation. The Remmers Funcosil range of hydrophobic impregnations is based on silicone, siloxane and silane resins, (with DTP approval) or tailored combinations of these to suit the structures requirements. Suitable protective impregnations should be selected according to the porosity and exposure of the concrete surfaces. Remmers Funcosil hydrophobic impregnations are also produced for application on masonry, natural stone and rendered facades. The innovative Funcosil Impregnation Creams have a unique consistency and characteristics which mean that they can be applied in a single coat to ensure optimum penetration of the hydrophobic material, and ensure the water repellency of the surface. Additional Remmers impregnation systems can strengthen and consolidate deteriorated surfaces making them suitable for the application of a protective waterproof coating. Remmers extensive range of protective coating systems use silicone, acrylic and other resin based weatherproof, waterproof and anti carbonation products. This includes the advanced Funcosil Elastoflex system, a highly protective crack bridging coloured coating. Remmers also produce specialist anti graffiti coating systems. 8

9 Innovation in Concrete Repair and Protection Technology A Selection of Successfully Completed Projects Southwick Hill Tunnel, A27, Sussex Cheltenham and Gloucester Building Society, Yeovil Boots Building D6, Nottingham Dundrum Car Park, Dublin The American Embassy, Dublin Car Park 3, Gatwick Airport 9

10 Repair and Protection of Concrete and Facades with Remmers Syste A Selection of Refurbishment Case Studies Lichfield Court Richmond, London Problem: 60 years of weathering and carbonation of all the exposed concrete surfaces, leading to steel reinforcement corrosion with subsequent cracking and spalling. Remmers Solution: Controlled cleaning of all surfaces, removal of damaged areas to expose all corroding reinforcement. Anti corrosion steel protection, polymer repair mortar and Funcosil Elastoflex crack bridging, anti carbonation and decorative, waterproof coating to all exposed surfaces. E-on Building Rayleigh, Essex Problem: The fluted surfaces of the precast panels had carbonated to a depth greater than the depth of the steel reinforcement in many places. This was allowing the steel to corrode progressively when and where water ingress occurred. Remmers Solution: Controlled cleaning of all surfaces, removal of damaged areas, exposure and cleaning of any corroding reinforcement. Anti corrosion steel primer, Betofix RM repair mortar, Funcosil migrating corrosion inhibitor and Elastoflex crack bridging anti-carbonation coating. 10

11 ms Structures Wentworth Club Wentworth, Surrey Problem: Cracking and spalling concrete over corroded steel reinforcement. Deteriorated original rendering and coatings. This well known building required a full refurbishment with a durable protective coating system. Remmers Solution: Patch repairs with Remmers repair mortars. Funcosil surface strengthening solution, followed by Funcosil LA silicone matt finish coating for high UV resistance, waterproofing and anti-carbonation protection, with excellent breathability. Plasmor Grain Silo Lowestoft, Suffolk Problem: Inadequate concrete cover over steel reinforcement and exposure to a marine atmosphere. Concrete cracking and spalling had developed progressively with the rate of concrete carbonation. Remmers Solution: High pressure water jetting to clean the surfaces with Rotec whirljet. Cleaning of exposed steel to remove rust and corrosion products. Remmers repair system with anti corrosive steel primer, polymer repair mortars and Funcosil Elastoflex crack bridging, anti-carbonation coating. 11

12 Concrete Repair and Protection with Remmers Systems Complementary Documentation Also Available From Remmers Stone and Masonry Restoration Flooring and Deck Waterproofing Basement and Cellar Waterproofing Extensive Documentation Remmers (UK) Limited Remmers House 14 Victoria Way Burgess Hill West Sussex RH15 9NF Tel: Fax: