Chemical attack in concrete SlideShare

Acid Resistance - Portland Cement Association

Acids attack concrete by dissolving both hydrated and unhydrated cement compounds as well as calcareous aggregate. In most cases, the chemical reaction forms water-soluble calcium compounds, which are then leached away. Siliceous aggregates are resistant to most acids and other chemicals and are sometimes specified to improve the chemical

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Heavy Metals Toxicity and the Environment

Heavy metals are naturally occurring elements that have a high atomic weight and a density at least 5 times greater than that of water. Their multiple industrial, domestic, agricultural, medical and technological applications have led to their wide distribution in the environment; raising concerns over their potential effects on human health and the environment.

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CORROSION OF CONCRETE REINFORCEMENT – CAUSES & REMEDIES

Dec 23,  · Corrosion of Concrete Reinforcement Corrosion is a chemical process of destruction of material because of its reaction with the environmental conditions. The most predominant among various factors of corrosion is the atmospheric corrosion which causes the rusting of steel. Appreciable corrosion only starts when the relative humidity of the air exceeds around 65%. In dry, []

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What is a Chemical Weapon? | OPCW

A Chemical Weapon is a chemical used to cause intentional death or harm through its toxic properties. Munitions, devices and other equipment specifically designed to weaponise toxic chemicals also fall under the definition of chemical weapons. All toxic chemicals and their precursors, except when used for purposes permitted by the CWC in

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PDF FRP/RTRP/GRP-Piping system for all Industrial Applications

Saving Time and Money-a Real Example 1400 Dia. Steel (C) 1400 Dia. GRP 1300 Dia. GRP 1200 Dia. GRP Head, mtr 105 60 82 115 Pump, KW 3156 1803 2464 3456

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Using Fly Ash in Concrete - National Precast Concrete

May 08,  · Properly proportioned concrete containing fly ash should create a lower cost. Because of the reduced permeability and reduced calcium oxide in properly selected fly ash, it should be less susceptible to the alkali-aggregate reaction. Sulfate and other chemical attacks

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What is Self Healing Concrete? its 2 Preparing Methods

Self-healing concrete is the process of self-healing up of cracks or self-filling of damages with the help of bacterial reaction in the concrete after hardening. The use of technology has taken the construction standards to a new high level in modern days. To attain a very good, sustainable, and economic concrete construction, different procedures, methods, and materials are used.

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PDF Challenges in material specification for concrete performance

Concrete DBV, 2001 German Society for Concrete and Construction Technology (superseded) Steel Fibre Concrete [DBV-Guide to Good Practice] BS EN 14889-1, 2006 British Standards Institution, EuroCode Fibres for Concrete. Steel Fibres. Definition, specifications and conformity DAfStb, German Committee for Reinforced Concrete Commentary on the

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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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Naphthalene | C10H8 - PubChem

Naphthalene is a white, volatile, solid polycyclic hydrocarbon with a strong mothball odor. Naphthalene is obtained from either coal tar or petroleum distillation and is primarily used to manufacture phthalic anhydride, but is also used in moth repellents.Exposure to naphthalene is associated with hemolytic anemia, damage to the liver and neurological system, cataracts and retinal hemorrhage.

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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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Defects in Concrete | Problems and Defects in Hard Concrete

Jan 02,  · Defects in concrete can often be related to the lack of durability of the concrete, resulting from the composition of the concrete, poor placement practices, poor Quality Control or the aggressive environment in which it is placed. Cracking, Spalling, Scaling, Honeycom , Settlement, Alkali Aggregate Reactions, Piping, Loss of binding paste.

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Cement hydration

Hydration products. The products of the reaction between cement and water are termed "hydration products." In concrete (or mortar or other cementitious materials) there are typically four main types: Calcium silicate hydrate: this is the main reaction product and is the main source of concrete strength. It is often abbreviated, using cement chemists' notation, to "C-S-H," the dashes indicating

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What is the role of base shear in RCC frame structure? - Quora

Each code in world for earthquake engineering uses base shear and total drift/intersotry drift as fundamental terms,uses forced based-elastic method incorporating non-linear behaviour from Response reduction factor(R). Since earthquake is not forc

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Alkali Aggregate Reaction in Concrete - Types, Causes, and

Some of the chemicals contain sodium and potassium compounds which may contribute to the alkali content of concrete. 4. Water. Water may contain a certain amount of alkali. 5. Alkalis from Outside Concrete. In the areas of cold weather, de-icing salt containing sodium compounds which may increase the alkali content on the surface layer of concrete.

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Concrete Spalling - Expert Article | Robson Forensic

Aug 17,  · Concrete cover varies for different exposures of the concrete member and for the conditions in which the concrete member is formed. For example, greater cover is required for greater exposure conditions, such as where the concrete element is cast against and permanently exposed to the ground, vs. being formed and located in an interior environment.

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PDF Materials for Embankment Dams - USSD

asphalt concrete as a water barrier; concrete facing rockfill dams; geosynthetics; reinforced fill; upstream slope protection; material for watertight cutoffs; and construction issues. For each of these topics, design and construction considerations are presented. USSD Committee on Materials for Embankment Dams Craig W. Harris, Chair

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Self-Healing Bio-Concrete | Giatec Scientific Inc

May 14,  · Bio-concrete is a self-healing form of concrete designed to repair its own cracks. It was developed by Dutch researcher and microbiologist Hendrik Jonkers using an extra ingredient acting as a healing agent and requires no human intervention to be repaired once placed. Bio-Concrete set to revolutionize the building industry: Dutch inventor of

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Mineral Admixture - an overview | ScienceDirect Topics

Chemical admixtures are used to improve the quality of concrete during mixing, transporting, placement, and curing. They are added to concrete in very small amounts mainly for the entrainment of air, reduction of water or cement content, plasticization of fresh concrete mixtures, or control of setting time. Specialty admixtures can include

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Concrete: Scientific Principles

Concrete has the ability to be molded or cast into almost any desired shape. Building of the molds and casting can occur on the work-site which reduces costs. Concrete is a non-combustible material which makes it fire-safe and able withstand high temperatures. It is resistant to wind, water, rodents, and insects.

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PDF NEWs & tErrorIsm

IED AttAck. ImprovIsED ExplosIvE DEvIcEs. What Is It? An . improvised explosive device (IED) attack. is the use of a "homemade" bomb and/or destructive device to destroy, incapacitate, harass, or distract. IEDs are used by criminals, vandals, terrorists, suicide bombers, and insur-gents. Because they are improvised, IEDs can come in many

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Remove Oil From Driveway With Soap & Oxygen Bleach

DEAR GUS: Motor and hydraulic oils can really cause a mess on concrete, brick and blacktop but the good news is that you can achieve excellent clean up results if you act quickly. Concrete Is Hard But Spongy. Concrete is a dense surface but water and many other liquids can and do soak into the surface. The fresh oil stain created by the dump truck will be a breeze to remove if you act quickly.

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Types of damage in concrete structures | Request PDF

Physical and chemical processes which lead to enlargement of the size and area of microcracks in concrete are classified. The electrochemical phenomenon responsible for corrosion of steel in

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PDF Admixtures for Concrete - Memphis

The effectiveness of water reducers on concrete is a function of their chemical composition, concrete tempera-ture, cement composition and fineness, cement content, and the presence of other admixtures. The classifications and components of water reducers are listed in Table 6-1. See Whiting and Dziedzic (1992) for more information on

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SUNNY GUPTA - Assistant Engineer - WSP in India

View SUNNY GUPTA'S profile on , the world's largest professional community. SUNNY has 3 jobs listed on their profile. See the complete profile on and discover SUNNY'S connections and jobs at similar companies.

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Durability of Concrete | Types of Durability and Factors

Feb 14,  · 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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Causes of Brick Deterioration and Decay in Buildings

After their initial mixing or casting, mortar, poured-in-place concrete and concrete masonry units shrink as the curing of the Portland cement proceeds. This is an unavoidable consequence of the curing of concrete products and is accommodated in design. Sulphate attack on brickwork

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What is pre packed concrete? - Quora

PRE-PECKED CONCRETE /PRE-PLACED AGGREGATE CONCRETE (PAC): * is a special technique of placing concrete under water. When 'tremie method' or 'bottom dump bucket method' are not found feasible, this method is adopted. s used where placing conventi

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Admixture - an overview | ScienceDirect Topics

Chemical admixtures are chemicals that are added during concrete mixing to achieve or alter specific properties in fresh and hardened concrete. Despite usually relative small quantities used in concrete mixtures comparing to other components, chemical admixtures have great impact on a variety of properties: workability, air content, accelerated

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Free Access to Scientific Journals - Open Access Journals

Open Access journals are the major source of knowledge for young and aspiring generations who are keen in pursuing a career in sciences. This system provides easy access to networks of scientific journals.Authors that contribute their scholarly works to Open Access journals gain remarkable reputation as the research scholarly explore these works extensively.

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Concrete Admixtures (Additives)- Types, Selection

Definition of Concrete Admixtures As per BIS (IS – 9103: 1999) Page , Concrete Admixture is defined as a material other than water, aggregates and hydraulic cement and additives like Pozzolana or slag and fiber reinforcement, used as on ingredient of concrete or mortar and added to the batch immediately before or during its mixing to modify one or more of the properties of concrete in

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