Products and systems for concrete rehabilitation
Products and systems for concrete remediation can be categorised into six main categories:
- Products and systems for reinforcement corrosion protection
- Products and systems for concrete repair
- Specific products and systems for waterproofing
- Bonding bridges
- Surface protection systems for concrete
- Products and systems for concrete injection
Products and systems for reinforcement corrosion protection
Anti-corrosion protection aims to shield metal surfaces from water and oxygen exposure to prevent electrochemical corrosion. It’s achieved through coatings, either with active pigments (active coatings) or as barrier coatings. This protection is essential if repair layers are not thick enough for effective coverage.
The anti-corrosion product should be applied after the reinforcement surfaces have been cleaned in order to prevent delamination. It is important to apply the product uniformly to prevent corrosion in localized areas.
The anti-corrosion protection can be textured by spraying silica sand to increase adhesion to subsequent layers such as mortar. Proper viscosity of such material is essential for ensuring that it fills the gaps between the reinforcement and the concrete.
Bonding bridges
Using bonding bridges promotes strong bonding by allowing operational materials to penetrate the concrete’s pores and chemically bond. They must be compatible with both the operational material and the concrete. Three common types are:
Challenges using this type of product include applying materials “fresh on fresh” and ensuring the adhesive bridge’s proper consistency and fluidity.
Products and systems for concrete repair
These materials serve to restore the original shape of the construction, increase cover layer thickness over reinforcement, or reinforce the structure itself. The materials are categorized into three groups: cement mortars and concretes (CC), polymer cement mortars and concretes (PCC) modified with polymer additives, and polymer mortars and polymer concretes (PC) using polymer resins as binders.
The essential requirements for these rehabilitation materials include high cohesion with the substrate, water resistance, frost resistance (at least T100), minimal volume changes due to environmental factors, limited shrinkage cracking, and an appropriate modulus of elasticity based on static function. Compressive or flexural tensile strength should match or slightly exceed that of the subbase if the material has a static function. Additionally, resistance to aggressive media must align with specific exposure conditions.
The EN 1504-3 standard categorizes concrete repair materials into several classes, each requiring specific performance criteria.
Surface protection systems for concrete
The purpose of surface protection systems is to prevent unwanted substances from being infiltrated into concrete structures, particularly into steel reinforcement. These substances primarily include carbon dioxide and water, although other aggressive agents may also be involved, depending on specific environmental exposures.
Additionally, surface protection systems enhance the appearance of repaired concrete structures.
However, it’s important to note that surface protection systems have limited effectiveness over time and cannot entirely replace a sufficiently strong and compact concrete cover layer or management mass above the reinforcement.
Implementation principles and challenges
Implementing surface protection systems requires adherence to manufacturer instructions regarding substrate preparation, application conditions, temperature ranges, open time, thinning options, and more. Proper storage and packaging of coating materials are essential.
Using these products and systems, it can be challenging to deal with issues such as voids, subsequent cracks, material loss, breach of cohesion, and moisture entrapment. Surface treatment systems must be selected based on factors such as compatibility, cohesion, and the potential for subsequent cracks. These systems play a crucial role in concrete protection and repair, serving various purposes, from waterproofing to enhancing surface texture.
Specific products and systems for waterproofing
- Elastomer Membranes: Elastomer membranes, used for waterproofing, are made from thermoset liquids or polymers, offering flexibility to accommodate movement without breaking. They include industrially produced insulation films and on-site-applied liquid materials.
- Crystallizing Coatings: Crystallizing coatings make concrete structures liquid-proof by inducing a reaction that forms insoluble crystals within the concrete, providing longterm waterproofing. Proper surface preparation is essential.
Products and systems for concrete injection
- Injection Materials: Grouting involves introducing materials to create barriers against liquids or vapours and restore structural integrity. Materials like polyurethane, acrylic, epoxy, and cement-based slurries are used.
- Filling Materials: Materials are absorbed into the concrete’s pores to fill gaps partially or fully. Some react with cement components, while others self-harden. Viscosity and substrate humidity are critical considerations during application.
