Structures The goal of installing a protection system is to lengthen the life of the structure while also lowering the number of future repairs and the rate at which concrete structures deteriorate. Materials and processes that give the following protective attributes make up protective systems: Steel reinforcement has a lower likelihood of corroding. Concrete degradation is reduced. Moisture, chloride ions, and other pollutants are less likely to penetrate the concrete. Surface treatments, electro-chemical equipment, or altering the PCC overlay can all be used to achieve this. Abrasion or impact resistance is improved. More protection against other harmful attacks. When recommending a protective system, the following considerations are taken into account:
Protective Systems for Reinforced Concrete
The various protective methods applicable for a given condition are compared in terms of life-cycle costs. When the expenses of future repairs are totaled throughout the structure’s expected life, the protection system with the lowest initial cost may really be the most expensive. If the protection system has a track record of success, users are more likely to trust it. The appearance of a system can sometimes be a deciding factor in its selection During the installation of the protection system, careful supervision, testing, and visual observations must be made. When deciding on a protective system, take into account noise and dust levels, hazardous chemical handling, use, and disposal, and vapour escape into the air. In addition, local environmental rules must be enforced.
The bond between the new protective system and the existing structure or previous repair material must be investigated. The expected life of a system must be weighed against its exposure to current atmospheric conditions. There must be no serious medical issues for the workers, as well as no risk of failure during the repair process.Factors that Influence the Need for a Protective System It is necessary to assess the factors that influence the performance of the performed repairs and the protective system. Some of the more frequent variables to consider in a repair and protection job are listed below.
Factors that Influence the Need for a Protective System
Deteriorated concrete or insufficient cover: Deteriorated concrete with severe internal cracking, internal voids, lack of consolidation, an insufficient entrained air-void system, or other poor circumstances can cause reinforcing steel corrosion and structural degradation.During a repair, the faulty concrete is removed. A well chosen protective system can help poor-quality concrete last longer, increase the performance of good concrete, and extend the life of any repair.Reinforcement corrosion. Misplaced reinforcing steel: When repairing or installing a protective system, extra material or coatings are applied to misplaced steel at ends, corners, hooks, and bars with less concrete cover. Cathodic protection, chloride extraction, and corrosion-inhibitor compounds in repair materials are all options for preventing or delaying further corrosion.
Water penetration: Hydrostatic pressure, moisture vapour pressure, capillary action, and rain can all cause water to permeate concrete. Cracks, porous concrete, a lack of entrained air, structural faults, or incorrectly designed or functioning joints can all cause water movement inside concrete.Moisture causes reinforcement corrosion, freezing and thawing damage, leakage into the structure’s interior, and possible structural damage. While designing the protective system, it was attempted to reduce water movement and directly control steel corrosion. Concrete water penetration corrosion carbonation Carbonation: Carbonation is the loss of concrete’s protective alkalinity due to carbon dioxide and moisture absorption. The naturally high alkalinity (pH above 12) of regular concrete protects the reinforcing steel.
Reinforced Concrete Structures
In the presence of high alkalinity, a protective oxide layer forms around the reinforcing steel, which helps to prevent the reinforcing steel from corroding. Carbonation is the loss of the usable alkalinity of concrete caused by the absorption of carbon dioxide and water within the concrete. When the pH falls below 10, the risks of corrosion increase considerably. Carbonation affects the bars close to the outer surface, and they are not protected against corrosion. Where concrete cover is insufficient, barrier coatings may give protection against further carbonation. Otherwise, a cathodic protection system or concrete realkalinization may be utilised to prevent steel from further corrosion.
When existing reinforcement extends from the parent concrete into a repair mortar or fresh concrete, this effect is known as anodic ring (halo effect). As a result, the electrical potential differences between the new and parent concrete at the bond line rise. An anodic ring, also known as a halo effect, is a type of failure caused by accelerated corrosion of the reinforcement in the parent concrete immediately beyond the repair’s edge. Electrons are drawn to the Cathodic section of the reinforcement in the uncontaminated repair material, causing corrosion at the anode, which is normally in the parent concrete. The development of rust creates high internal pressures at the surface of the reinforcement, causing concrete to spall. This process is accelerated by the presence of chlorides.
Protective Systems for Reinforced Concrete Structures
Barrier coatings on reinforcing steel, such as epoxies, latex slurries, or zinc rich coatings, can assist prevent corrosion activity to some extent, however there are issues with field application. Steel can also be protected against corrosion by using cathodic protection, chlorine extraction, and galvanic anodes. However, the economics of these solutions must be taken into account.halo effect or ring anode Cracks: The initial step in any repair or protection job is usually to mend cracks. In cold climates, water in cracks can cause corrosion and freezing and thawing issues. Before repairing a crack, it’s important to figure out why it appeared in the first place. Structural cracks must be fixed in such a way that load may be transferred through the crack. Epoxy injection is a procedure that involves injecting epoxy resin into the.
Properly constructed expansion / contraction joints can be used to mend cracks that are active during thermal movement. Moving cracks can be repaired with caulking, chemical grouts, elastomeric coatings, and high elongation epoxies. Active cracks on outside exposures might be difficult to repair. The majority of crack-repair products are temperature-sensitive and cannot be installed below 4 degrees Celsius. Because most flexible materials used in active crack repair function better in compression than in tension, it is also preferable to execute repairs while the crack is nearing its maximum width.cracks in concrete chloride-chemical-attack Chloride/chemical attack: Chemical or salt solutions penetrating through concrete cause the embedded steel to corrode. Acids, alkalis, and sulphates can all cause chemical damage.
Concrete Durability
The growing demand for concrete structure reconstructions, as well as the vast availability of surface protection goods and systems on the market, may lead to mistakes in the selection of the most appropriate solution. Because of their properties, surface protectors have become increasingly common in recent years in concrete restoration interventions. They can protect the substrate from aggressive agents, thereby extending the useful life of the structures. The purpose of this essay is to introduce the various surface protective treatments available on the market, as well as their benefits and drawbacks. Following that, a characterization of seven different commercial coatings for reinforced-concrete structures is offered, taking into account chemical nature, fields of application, and efficacy, both in terms of physic and elastic performance and durability.
In recent years, the notion of sustainability has gained traction in the construction industry, with a particular focus on structure durability. In reality, construction materials capable of providing a long service life, even if characterised by a high environmental effect resulting from their production, could be significantly more sustainable than “green” materials, whose longevity is sometimes uncertain. As a result, one of the most important tactics for ensuring the long-term viability of building materials is to increase their durability, lowering the economic and environmental costs of repairs or, worse, destruction and reconstruction.
such as bridges, dams, piers, tall buildings and stadiums.
reinforced concrete, concrete in which steel is embedded in such a manner that the two materials act together in resisting forces.
Use a PVC pipe of the required size to slide over the exposed rebars.
Also Check
Marshall Stability Test – Flow Test on Bitumen