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Chemical attack in concrete SlideShare

Chemical attack in concrete SlideShare

Chemical attack in concrete - SlideShare

Sep 29, 2014  Chemical attack in concrete. 1. Chloride Attack Chloride attack is one of the most important aspects while dealing with durability of concrete. It primarily

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Chemical attack on concrete - SlideShare

Sep 26, 2016  Concrete acts as the electrolyte, and the metallic connection is provided by wire ties, chair supports, or the rebar itself. 5. Chemical attacks: Chloride attack

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Chemical attack on concrete 2017 - SlideShare

Mar 07, 2017  Chemical attack is the reaction of chemical elements from exposure and moisture present in the concrete which results into deterioration of RCC structure. THE

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Chemical attack - SlideShare

Jan 15, 2018  2. 9/12/2015 2 INTRODUCTION Most frequent form of chemical attack are due to sulphates, sea water natural acidic water. Concrete permeability is the single most

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Chemical attack on the durability of ... - SlideShare

Aug 18, 2016  Chemical attack on the durability of underground structures 1. Chemical attack on the durability of underground structures Workshop Middle East Concrete

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Chemical attack in concrete - SlideShare

Chemical attack in concrete. 1. Chloride Attack Chloride attack is one of the most important aspects while dealing with durability of concrete. It primarily causes corrosion of reinforcement. Statistics have indicated that over 40% of failure of structures is due to corrosion of steel. Concrete

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Properties of concrete - SlideShare

Mar 04, 2016  2.3.6 Durability The ability of concrete to withstand the conditions for which it is designed without deterioration for a long period of years is known as durability or Durability of concrete may be defined as the ability of concrete to resist weathering action, chemical attack

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Properties of Concrete - Portland Cement Association

Sulfate Attack. Others. The durability of concrete may be defined as the ability of concrete to resist weathering action, chemical attack, and abrasion while maintaining its desired engineering properties. Concrete is exposed to a greater variety of potentially harmful exposure conditions than any other construction material.

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High-Performance Concrete, Chapter 17 - Memphis

Resistance to chemical attack Expose concrete to saturated No deterioration after 1 year solution in wet/dry environment Sulfate attack ASTM C 1012 0.10% max. expansion at 6 months for moderate sulfate exposures or 0.5% max. expansion at 6 months for severe sulfate exposure

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Protecting Concrete Tanks in Water and Wastewater ...

Dec 28, 2000  This expansion from within creates large tensile forces within the concrete. Since concrete is relatively weak in tension, the concrete cracks to relieve the tensile stresses (Figure 3). Once the concrete cracks, water, oxygen and aggressive chemicals can freely enter the concrete and attack the embedded rebar and the deterioration process ...

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(PDF) Corrosion of Steel in Concrete Professor Dr ...

Corrosion of Steel in Concrete Understanding, investigation and repair 2nd edition John P. Broomfield

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Chemical disruption - BrainKart

Chemical disruption . Resistance of concrete to chemical attack: ü The cement composition used in the concrete.. ü Conditions under which the cement paste hardened . ü All determine properties of concrete . 1Sulphate Attack . Mechanism-sulphates are found in most of the soils as calcium, potassium, sodium and magnesium sulphates.

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Chloride Attack on Concrete Structures - Cause and ...

Prevention of Chloride Attack on Concrete Structures Several methods are available in order to prevent the effect of chlorides on concrete structures. Some of them are: Increasing the cover over the reinforcement bar. This is the simplest way to prevent chloride attack. Studies have shown that an increase in cover by one inch can increase the ...

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Plant Engineering Corrosion: Chemical oxidation

Feb 11, 2011  Concrete corrosion. Corrosion in concrete can happen two ways, through the reinforcement bars and through chemical attack. Corrosion of the concrete though the reinforcement bars is a form of electrochemical corrosion because of the moisture that makes its way to the bars through the concrete since it’s very porous.

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Properties Of Hardened Concrete - Engineering Discoveries

Thus, when concrete laid at 30°C cools down to 15°-18°C, some shrinkage may be expected. It may be negligible on its own account. But when added to drying shrinkage, it becomes necessary. 3- Durability. Environmental forces such as weathering, chemical attack, heat, freezing, and thawing try to destroy concrete.

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ABRASION RESISTANCE OF CONCRETE AND THE USE OF

Concrete deterioration primarily results from some combination of the following mechanisms: abrasion and hydraulic pressure cracking at rail seat, freeze-thaw damage, chemical attack like alkali silica reaction (ASR), and cracking under impact and frequent dynamic loads[2]. One possible solution to this problem is the use of high performance ...

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Types of damage in concrete structures - ScienceDirect

Jan 01, 2009  The chemical causes of concrete damage can be grouped into three main categories: 3 (i) hydrolysis of the cement paste components by soft water; (ii) cation-exchange reactions between aggressive fluids and the cement paste; and (iii) reactions leading to formation of expansive products, such as in the case of sulfate attack, alkali–aggregate ...

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Concrete degradation - Wikipedia

Various types of aggregate undergo chemical reactions in concrete, leading to damaging expansive phenomena. The most common are those containing reactive silica, that can react (in the presence of water) with the alkalis in concrete (K 2 O and Na 2 O, coming principally from cement). Among the more reactive mineral components of some aggregates are opal, chalcedony, flint and strained quartz.

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Supplementary Cementitious Materials — What, why, how ...

Watertight concrete will reduce various forms of concrete deterioration, such as corrosion of reinforcing steel and chemical attack. Most supplementary cementitious materials can reduce internal expansion of concrete due to chemical reactions such as alkali aggregate reaction and sulfate attack. Resistance to freezing and thawing cycles ...

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STUDY OF MECHANICAL AND DURABILITY ... - slideshare

Concrete exposed to marine environment is subjected to several types of aggressive agents: mechanical agents, such as waves and tides, and erosion due to the effects of the waves; chemical attacks due to the action of chlorides present in seawater and sulfates, and climatic agents due

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Concrete in Aggressive Environment - SlideShare

Concrete in Aggressive Environment. 1. Concrete in Aggressive Environment Unit-6. 2. Syllabus• Concrete in Aggressive Environment: Alkali – Aggregate Reaction, Sulphate Attack, Chloride Attack, Acid Attack, Effect of Sea Water, special coating for Water Proofing, Sulphate Chloride and Acid attack, Concrete for hot liquids. 3.

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Types and Causes of Concrete Deterioration

Concrete can deteriorate for a variety of reasons, and concrete damage is often the result of a combination of factors. The following summary discusses potential causes of concrete deterioration and the factors that influence them. CORROSION OF EMBEDDED METALS Fig. 1. Corrosion of reinforcing steel is the most common cause of concrete ...

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Types of damage in concrete structures - ScienceDirect

Jan 01, 2009  The chemical causes of concrete damage can be grouped into three main categories: 3 (i) hydrolysis of the cement paste components by soft water; (ii) cation-exchange reactions between aggressive fluids and the cement paste; and (iii) reactions leading to formation of expansive products, such as in the case of sulfate attack, alkali–aggregate ...

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ABRASION RESISTANCE OF CONCRETE AND THE USE OF

Concrete deterioration primarily results from some combination of the following mechanisms: abrasion and hydraulic pressure cracking at rail seat, freeze-thaw damage, chemical attack like alkali silica reaction (ASR), and cracking under impact and frequent dynamic loads[2]. One possible solution to this problem is the use of high performance ...

get price

Supplementary Cementitious Materials — What, why, how ...

Watertight concrete will reduce various forms of concrete deterioration, such as corrosion of reinforcing steel and chemical attack. Most supplementary cementitious materials can reduce internal expansion of concrete due to chemical reactions such as alkali aggregate reaction and sulfate attack. Resistance to freezing and thawing cycles ...

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Carbonation of Concrete - In-depth Overview - Structural Guide

It is a process of reacting calcium hydroxide in the concrete with carbon dioxide in the atmosphere and creates a calcium carbonate and water. Ca (OH) 2 + CO 2 → CaCO 3 + H 2 O. This process starts with the concrete surface and it gradually moves towards the inner of the concrete. Carbonation of concrete is a slow and continuous process.

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Carbonation of concrete - Understanding Cement

Carbonation is the result of the dissolution of CO 2 in the concrete pore fluid and this reacts with calcium from calcium hydroxide and calcium silicate hydrate to form calcite (CaCO 3 ). Aragonite may form in hot conditions. Within a few hours, or a day or two at most, the surface of fresh concrete will have reacted with CO 2 from the air.

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Repairs and Rehabilitation of Concrete Structures for ...

Resin based Repairs of Concrete The resins normally used are from epoxide, polyester, acrylic or polythene families. The application of resins for repair work requires a thorough understanding of their chemical and physical properties and their performance in the structure, particularly with the passage of time and under unfriendly environs.

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Cement - The major cements: composition and properties ...

Set cement and concrete can suffer deterioration from attack by some natural or artificial chemical agents. The alumina compound is the most vulnerable to chemical attack in soils containing sulfate salts or in seawater, while the iron compound and the two calcium silicates are more resistant. Calcium hydroxide released during the hydration of ...

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Chemical Admixtures – Its Types, Advantages, and ...

Feb 27, 2021  Chemical admixtures are the ingredients in concrete other than Portland cement, water, fine aggregates, and coarse aggregates that are added to the mix immediately before or during mixing concrete. Producers utilize chemical admixtures to reduce the cost of concrete construction; to modify the properties of hardened concrete; to ensure the concrete quality during mixing, transporting,

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Alkali-Aggregate Reaction

Alkali-Aggregate Reaction. In most concrete, aggregates are more or less chemically inert. However, some aggregates react with the alkali hydroxides in concrete, causing expansion and cracking over a period of many years. This alkali-aggregate reaction has two forms: alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR).

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Durability of Concrete Types of Durability and Factors ...

Feb 14, 2017  Durability is defined as the capability of concrete to resist weathering action, chemical attack and abrasion while maintaining its desired engineering properties. It normally refers to the duration or life span of trouble-free performance. Different concretes require different degrees of durability depending on the exposure environment and properties desired.

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Alkali Silica Reaction - an overview ScienceDirect Topics

Mar 02, 2012  P. Ziehl, M. ElBatanouny, in Acoustic Emission and Related Non-Destructive Evaluation Techniques in the Fracture Mechanics of Concrete (Second Edition), 2015 11.2.1 Alkali–silica reaction. Alkali–silica reaction (ASR) is a material degradation mechanism that occurs in concrete structures. ASR is a chemical reaction occurring between the reactive siliceous aggregate particles and hydroxyl ...

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