Pdf corrosion of reinforcing bars astm a706 in self. Sulphate attack in concrete, its effects, causes and. Chemical attack to concrete by soil sulfate and chloride. Chloride ions control of sulphate attack solution of the sulfates of various bases including sodium, potassium, magnesium and calcium react. In footings construction, it is very important to protect the reinforced concrete in direct contact with the soil from the ground water attack, especially if it is consisting of risky salt such as nacl. The compounds present in cement concrete are attacked by many salt solutions and acids.
It cannot be determined directly in a time frame that would be useful as a quality control measure. Does experience confirm that different chloride salts may influence concrete in different ways. This research compares singleion attack and combined attack. Sulphate attack on concrete can appear in different forms. Corrosion of reinforced concrete rc structures is one of the significant causes of deterioration of reinforced concrete rc structures. The decrease in ph in the concrete is caused by carbonation, infiltration of chloride 2, 3, magnesium salts and sulfate, and acid attack by bacteria. C2, w0 f0, s0, c0, w0 f3, s0, nrmca expanding the concrete. Durability and aesthetics of architectural concrete under. Pdf concrete durability continues to be a subject of challenges for design professionals, and specialist of concrete. Chloride attack poses a significant threat to reinforced concrete especially for structures in marine environments or those that are likely to be exposed to high concentrations of salts. The tubs are leaking and the client wants an investigation into the condition of the floor, and the structural integrity of the floor. The mechanism of chlorideinduced corrosion of steel embedded in concrete, the ingress of chlorides into the concrete, and the threshold chloride content for.
Now, several researches on the chlorination of concrete structures have been ongoing around the world. Furthermore, architectural concrete also possesses excellent carbonation resistance based on the carbonation depth data obtained from the carbonation experiment. But due to chloride attack on concrete, reinforcement steel gets corroded. Effect of combined sulfatechloride attack on concrete durabilitya. Effect of chloride and sulfate contamination in soils on.
However, several factors influence concrete resistance against chlorides and sulphates. Also, the figure shows that bs total chloride limit for this type of concrete is not violated in mix m1 and m2 even though the bs. Sulphate attack is the result of interaction between sulphate ions and hydrated cement products. Chloride attack is particularly important because it primarily causes corrosion of reinforcement. Hardened concrete an overview sciencedirect topics. The first line of defense against chemical attack is to use quality concrete with maximum chemical resistance. Effect of carbonation, chloride and sulphate attacks on reinforced concrete. Chloride induced corrosion of reinforcement steel in concrete.
National ready mixed concrete association, silver spring, md. Pdf chloride attack evaluation on concrete compositions. Sodium chloride does not attack concrete chemically but cont r ibutes to the corrosion of re i n f o r cing steel and, when used as a deicer, participates in and aggravates physical damage re s u l t i n g f r om fre e zing. Chloride attack chloride attack is one of the most important aspects while dealing with durability of concrete.
The risk of corrosion increases as the chloride content of concrete increases. Interaction of chloridesulfate ions on concrete deterioration is ery complicated. Xianming shi, yajun liu, matthew mooney, michael berry, barrett hubbard, laura fay, andrea beth leonard 9. Mechanism of different chemical attacks in a concrete like chloride attack, sulfate attack, which causes corrosion and spalling. The aggressive action of the sulfate ion on concrete is discussed by. Chloride and sulfate ions damage the reinforced concrete in marine environment due tothe corrosion and formation of expansive products, respectively. The ability of chloride ions to penetrate the concrete must then be known for design as well as quality control purposes. Effect of calcium chloride on the compressive strength of. Finally, the infiltration of chloride ion in the concrete also decreases the compressive strength 4, 5. Relationship between concrete strength and wc ratio at various ages ref 3. Therefore, architecture concrete served as protection covers can withstand both the chloride attack and carbonation tested in this paper. Among all sources of failure of concrete structures, the chloride attack accounts 40% contribution. The concrete ph decreases when the chloride ion attacks. Resistance of concrete against combined attack of chlorides.
The binding of chloride ions by cement compounds and the associated effect of using different cements, both portland and blended, as well as other factors influencing corrosion, are considered. How does chloride affect the properties of concrete. Chloride attack in wetting and drying exposure by concrete construction staff a brine with a high content of calcium chloride is leaking through the concrete linings of a potash shaft and causing severe deterioration of the concrete linings. At a scan speed of 100 ms, a spatial resolution of 300400 m and limits of detection of 0. He is also a fellow of astm, and the engineering institute of canada. The chloride distributions along the concretesteel interface and possible differences between. Contents sources of sulfates internal sources external sources main factors affecting sulphate attack 1. Their role in concrete durability march 99 attackpenetration has been the subject of much research in recent years. Chloride limits will generally preclude the use of chloridebased admixtures in. Chemical attack of strong chloride solutions on concrete. Chlorides affect durability by initiating corrosion of the reinforcement steel, and sulphates by deteriorating the concrete through formation of expansive reaction products. A lot of damage is reported for constructions in marine environments, due to aggressiveness of sea water containing chlorides and sulphates. Chloride initiates the corrosion of embedded reinforcements, which not only produces signs of deterioration on the concrete surface, such as rusting, cracking and spalling, but. Chloride attack poses a significant threat to reinforced concrete especially for structures in marine environments or those that.
Effect of combined sulfatechloride attack on concrete. Chloride content test for concrete determines the level of chloride ions and ingress of the chloride ion which destroys the protective layer of steel. Chemical attack of seawater on concrete the potentially aggressive constituents of seawater with respect to concrete are the sulfate, chloride, carbonate, bicarbonate, alkali metal, and magnesium ions. Chloride attack on concrete structures cause and prevention. The penetration of the concrete by chloride ions, however, is a slow process. The mechanism of chlorideinduced corrosion of steel embedded in concrete, the ingress of chlorides into the concrete, and the threshold chloride content for corrosion to occur are discussed. Interaction of chloridesulfate ions onconcrete deterioration is very complicated. Sulphate attack in concrete, its effects, causes and prevention. Though hno 3 is not as strong as h 2 so 4, its effect on concrete at brief exposure is more destructive since it transforms ch into highly soluble calcium nitrate salt and low soluble calcium nitroaluminate hydrate nitric acid attack is a typical acidic corrosion for shrinkage of the corroded layer due to leaching of highly soluble calcium nitrate. A propagation period in which active corrosion commences and cracking of the cover concrete occurs due to the formation of expansive corrosion products at the steel surface. Chloride attack in wetting and drying exposure concrete. Evaluating effect of chloride attack and concrete cover on.
Pdf effect of carbonation, chloride and sulphate attacks on. Chloride and sulfate ions damage the reinforced concrete in marine environment due to the corrosion and formation of expansive products. The mechanism of chloride induced corrosion of steel embedded in concrete, the ingress of chlorides into the concrete, and the threshold chloride content for corrosion to occur are discussed. Chloride limits are expressed on the basis of the weight of portland cement.
In addition to the two methods that can help to prevent a chloride attack, concrete can also be protected against a sulfate attack by limiting the aluminates to a level between 3% and 8%. Evaluation of chloride limits for reinforced concrete phase a. Chlorides can be introduced into the concrete either during or after construction as follows. Testing chloride penetration resistance of concrete. I have an existing concrete floor beam and slab that supports some hottubs built above the floor with grout and tile.
These chemicals are encountered by almost all concrete structures. Little research has been conducted in this respect. The net result of chloride attack is the corrosion of steel reinforcement, leading to cracking and spalling of concrete and in some cases catastrophic. Dec 01, 2012 1,2,3 chloride attack is one of the most important aspects for consideration when we deal with the durability of concrete. Chemistry of chloride attack on concrete 4 it is claimed that sodium or potassium chioride solutions, and also magnesium or calcium chioride solutions in such a low concentration that the expansive c1110rohydroxide hydrates do not form, are able to cause a. Article 1, volume 1, issue 2, summer and autumn 2017, page 103110 pdf 604 k. These threshold chloride values can be approximated to about 0. Anderson award winner, and a member of numerous aci committees including c232 on fly ash and c201 on durability.
Article 1, volume 1, issue 2, summer and autumn 2017, page 103110 xml pdf. Pdf effect of carbonation, chloride and sulphate attacks. According to research, blended cements perform better than ordinary portland cement when subjected to a sulfate attack, and pozzolanic materials such as fly. In this study, the effect of chloride ions on sulfate attack and effect of sulfate ions on chloride attack were. Effects of substances on concrete and guide to protective. Chloride attack is a major deterioration factor for concrete structures in japan. The main effect of chloride attack is the corrosion of reinforcement that induces the strength of the.
Corrosion of reinforcing bars astm a706 in selfcompacting concrete subjected to chloride attack and carbonation. Chloride attack on concrete is one of the important aspects of durability of concrete. Jul 17, 2016 contents sources of sulfates internal sources external sources main factors affecting sulphate attack 1. Physical salt attack on concrete, part 2 aci spring 2012 convention march 18 21, dallas, tx r. Pdf effect of ground water sodium chloride attack on. Effect of chloride based deicers on reinforced concrete structures july 2010 6. Calcium chloride has been used in concrete since 1885 and finds application mainly in cold weather, when it allows the strength gain to approach that of concrete cured under normal curing. The main effect of chloride attack is the corrosion of reinforcement that induces the strength of the structure drastically. Effect of chloridebased deicers on reinforced concrete. In such situations, use of type v cement, though providing adequate protection against sulfate attack, fails to remove free chlorides from concrete. Hydrochloric acid attack on concrete the chemicals formed as the products of reaction between hydrochloric acid and hydrated cement phases are some soluble salts and some insoluble salts. To inhibit reinforcement corrosion, cement with a high tri calcium aluminate c 3a content should be used 4. Statistics have indicated that over 40% of failure of structures is due to corrosion of steel.
Statistics have indicated that over 40% of failure of structures is due to corrosion of reinforcement a. Chlorination is a major process governing the initiation and advancement of the injurious corrosion of steel bars. Soluble salts, mostly with calcium, are subsequently leached out, whereas insoluble salts along with amorphous hydrogels, remain in the corroded layer. Chloride content test for concrete structure durability. Mar 03, 2015 calcium chloride is available in two forms. Chloride attack evaluation on concrete compositions according to brazilian standard abnt nbr 6118 specification article pdf available december 2016 with 674 reads how we measure reads. Chloride attack on concrete structures is one of the most important phenomena we consider when we deal with the durability of concrete.
A particular feature of chloride attack which dis tinguishes it from other mechanisms of deterioration of reinforced concrete is that the primary action of chlorides is to cause corrosion of steel reinforcement, and it is only as a consequence of this corrosion that the surrounding concrete is damaged. The penetration of chloride through cementbased materials is of great importance because chlorides are one of the main agents. Key words reinforced concrete, prestressed concrete, chlorides, corrosion, corrosion protection, reinforcing steel, grout, corrosion inhibitors. Effect of combined sulfatechloride ttack on concrete. Combined attack simulates concrete deterioration in marine environments more realistically.
Neville 1995 according to the author, the chloride attack on concrete is different from other mechanisms of deterioration because the primary action of chlorides is to cause corrosion of steel reinforcement and it is only as a consequence of this corrosion that the surrounding. Analysis of total chloride content in concrete sciencedirect. Effect of chloridebased deicers on reinforced concrete structures july 2010 6. In this study, the effect of chloride ions on sulfate attack and effect of sulfate ions on chloride. Deicing salts are a major cause of corrosion of reinforcing steel in concrete. Relationship between coefficient of permeability and watercement ratio ref 4. This publication discusses the effects of many substances on concrete and provides guidelines to protective treatments. Maintenance of concrete bridges deteriorated by chloride. Chloride limits will generally preclude the use of chloride based admixtures in reinforced and prestressed concrete. Interaction of chloride sulfate ions on concrete deterioration is ery complicated. Chloride attack is one of the most important aspects for consideration when we deal with the durability of concrete. Chemical attack to concrete by soil sulfate and chloride jedclampett structural jan 12 11. The alkaline environment is created by the hydration of the cement in concrete. Chloride attack of reinforced concrete corrosion rust.
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