A suite of 10 synthetic sodium silica and sodium calcium silica gels was prepared to explore the basic mechanism of expansion of concrete by alkalisilica reaction. Use a low alkali cement alkali silica reaction in concrete free ebook download as pdf file. Soluble alkali salts, typically sodium and potassium, exist in concrete ingredient mate rials, primarily from the portland cement. Effect of natural pozzolans on the alkalisilica reaction. Repair of reinforced concrete beams damaged by alkali. Concrete technology diagnosis and control of alkaliaggregate. Asr is a chemical reaction between the reactive silica contained in the aggregates and the alkalis within the cement paste 1, 2 and 3. Alkalisilica reaction asr and delayed ettringite formation def, or combinations of the two, have been found to be the main causes of these problems. Concrete affected by the variety of alkali aggregate reaction known as alkali silica reaction often shows exudations of a watery gel which dries to a white deposit. Question on alkalisilica reaction the concrete society. Supplemental information should be developed to confirm that the expansion is actually due to alkalisilica reaction. Aug 23, 20 rob winbank on control of cracking in reinforced concrete structures about us civilax based to server in civil engineering provides etabs and sap2000 tutorials, civil engineering spreadsheets, civil engineering ebooks and many more civil engineering downloads. The reaction can be visualized as a twostep process.
The result is an alkalisilica gel that absorbs water and increases in volume. Risk of alkalisilica reaction when using recycled concrete. Effect of alkalisilica reaction on the structural behavior. This gel is hydrophilic, hygroscopic, and expansive. Standard test method for determination of length change of. The most common of these is the alkali silica reaction asr.
In 1992 a first edition entitled the alkalisilica reaction in concrete, edited by professor narayan swamy, was published in a first attempt to cover this concrete. In acr, the reaction is between the alkalies sodium and potassium and certain carbonate rocks, particularly calcitic dolomite and dolomitic limestones, present in some aggregates. The aggregates varied their origin and mineralogical composition. Alkali silica reaction asr and alkali carbonate reaction acr. Test sections that utilized selected mixes from this study were placed during the summer of 2008 in wyandotte county, kansas. The varying nature of the aggregates used in concrete signifies that many different alkali aggregate reactions can be observed. Alkalisilica reaction and delayed ettringite formation. This alkali aggregate reaction has two forms, namely.
Alkalisilica reaction in portland cement concrete 16. Acr is a serious, but fortunately rare, variety of. This distress has been mainly attrib uted to alkalisilica reaction asr and delayed ettringite formation def and. In 1992 a first edition entitled the alkalisilica reaction in concrete, edited by professor narayan swamy, was published in a. It occurs when the alkaline pore fluid and siliceous minerals in some aggregates react to form a calcium alkali silicate gel. The reaction chemistry of the swelling and dissolution of disordered silica in alkali hydroxide solutions in the absence of calcium hydroxide is reasonably well understood. Concrete affected by the variety of alkaliaggregate reaction known as alkalisilica reaction often shows exudations of a watery gel which dries to a white deposit. This usually occurs between the highly alkaline portland cement and the various siliceous substances contained in the aggregate. The microscopic examination was carried out on concrete. This causes a gel to form within the cement paste matrix. The classical explanation of the reaction is given by wang 1991. Three main types of alkali aggregate reaction aar have been identified depending on the aggregates.
Sk saxena pmp introduction alkali silica reactivity asr is an expansive reaction between reactive forms of silica in aggregates and potassium and sodium alkalis, from cement, aggregates, admixtures water moisture, and pollution of land. Alkaliaggregate reactions in concrete sciencedirect. Alkalisilica reaction in concrete, 1 jan 1988 4154. Repair of reinforced concrete beams damaged by alkalisilica.
The use of surplus waste glass in concrete has been avoided on the grounds that it is known to undergo harmful alkalisilica reaction asr. Presents test data on the structural deformations and strength of reinforced concrete beams undergoing alkalisilica reaction asr. Dr jason eidiker of oregon state university presents his research on alkali silica reaction of concrete. The expansive reactions between alkalis and alkalireactive aggregates within concrete structures are a problem which has been known about since the mid. Identifying the alkali silica reaction asr in concrete is one of the most recognized harmful phenomena in concrete. Mathematical model for kinetics of alkalisilica reaction in. Kishore kaushal alkalisilica reaction in concrete, ici bulletin june, 1990, pp.
Alkali aggregate reactions can be either alkali carbonate reactions acrs or alkali silica reactions asrs. In absorbing water, these gels can induce pressure, expansion, and cracking of the aggregate and surrounding paste. Kaushal kishore for submitting the paper on alkali silica reaction in concrete. Preventing alkalisilica reaction and delayed ettringite formation in new concrete introduction the state of texas has been widely impacted by materialsrelated distress in various transportation structures. Alkalisilica reactivity, alkaliaggregate reaction, reactive aggregates, concrete durability, concrete, prescriptive, preventive, control, pp65. Effect of natural pozzolans on the alkalisilica reaction of. Nevertheless, in many areas of the country, the good aggregates have been used up, and poorer aggregates, of necessity or for unknown reasons, are. Use a low alkali cement alkali silica reaction asr. Alkalisilica reaction in concrete containing glass. Apr 07, 2017 for the love of physics walter lewin may 16, 2011 duration. Asr is based on the dissolution of silicarich aggregates in highly alkaline solutions in concrete constructions e.
Presents test data on the structural deformations and strength of reinforced concrete beams undergoing alkali silica reaction asr. Preventing alkalisilica reaction and delayed ettringite. The result is an alkali silica gel that absorbs water and increases in volume. The effects of supplementary cementitious materials on alkali. The alkalisilica reaction forms a gel that swells as it draws water from the surrounding cement paste. A case study of alkali silica reaction in highdensity concrete escadeillas, g. Alkali silica reactive take preventive measures or do not use. This is a short introduction to asr for more information, see the understanding cement bookebook. Alkali aggregate reaction topic american concrete institute. From that time chemistry of asr has been studied by numerous researchers, e. Alkalisilica reactivity field identification handbook fhwa. Expansion due to alkali silica reaction asr has caused serious consequences in many concrete structures around the world. Concrete prism test, astm c 1293 is 1year expansion reaction expansion due to acr or asr.
Reaction products from asr have a great affinity for moisture. Concrete technology diagnosis and control of alkali. The alkalisilica reaction in concrete civil engineering. When calcium hydroxide is present, dissolved silica reacts to form calcium silicate. What is alkalisilica reaction asr and how can i recognise it. What is alkali silica reaction asr and how can i recognise it. Alkali silica reaction in concrete alkali silica reaction asr can cause serious expansion and cracking in concrete, resulting in major structural problems and sometimes necessitating demolition. Concrete alkali silica reaction presentation youtube.
The term premature concrete deterioration pcd has been adopted to refer to problems. Kaushal kishore for submitting the paper on alkalisilica reaction in concrete. Alkalisilica reaction asr is the most common form of alkaliaggregate reaction. Jan 20, 2009 the use of surplus waste glass in concrete has been avoided on the grounds that it is known to undergo harmful alkali silica reaction asr. Chemical analysis of these exudations or deposits shows them to be composed mainly of silica and alkali often with varying amounts of lime. Asr involves reactions between alkali pore solution in the concrete and certain forms of alkali reactive silica. Kishore kaushal alkali silica reaction in concrete, ici bulletin june, 1990, pp. Petrographic examination of the concrete prisms should be conducted. Identifying the alkalisilica reaction asr in concrete is one of the most recognized harmful phenomena in concrete. This document is available to the public through the national technical information service, springfield, va 22161. Alkalisilica reaction in concrete numerical modelling. As asr is potentially a very destructive reaction within concrete.
Abstract identifying the susceptibility of an aggregate to alkali silica reaction asr before using it in concrete is one of the most efficient practices for preventing damage and failure. Asr is based on the dissolution of silica rich aggregates in highly alkaline solutions in concrete constructions e. Alkali silica reaction asr and delayed ettringite formation def, or combinations of the two, have been found to be the main causes of these problems. A case study of alkalisilica reaction in highdensity concrete escadeillas, g. Selecting measures to prevent deleterious alkalisilica. Silica reaction in table 3 of astm c618 2005, standard specification for coal fly ash and raw or calcined natural pozzolan for use in concrete, was not allowed to be used in concrete mixes for kdot projects. Alkaliaggregate reactions can be either alkalicarbonate reactions acrs or alkalisilica reactions asrs. Alkalisilica reaction and microstructure of concrete. Abstract identifying the susceptibility of an aggregate to alkalisilica reaction asr before using it in concrete is one of the most efficient practices for preventing damage and failure. There are a number of astm tests used to identify alkali silica reactive aggregates, and the effects of different alkali bearing cements and pozzolans in accommodating the asr reaction. Pdf ultrasonic nondestructive evaluation of alkali. Mathematical model for kinetics of alkalisilica reaction.
To establish the full extent of the effects of asr, the beams were singly reinforced with shear links. Alkali silica reactivity, alkali aggregate reaction, reactive aggregates, concrete durability, concrete, prescriptive, preventive, control, pp65. Alkali silica reactivity asr is considered as concrete cancer, and mat take 10years to 15 years to show its symptom of degradation. In concrete or mortar or other cementitious materials there are typically four main types. Alkali silica reaction asr in concrete is now a wellknown threat to the concrete structures.
Alkali silica reaction asr mitigation in concrete by using. Selecting measures to prevent deleterious alkalisilica reaction in. At first sight, and when looked at superficially, the problem of alkali silica reaction asr may appear to be similar to the other deterioration processes that cause damage to concrete with which researchers and engineers are already familiar. Alkalisilica reactivity, alkaliaggregate reaction, reactive aggregates, concrete durability, field identification, concrete. The former is of higher concern since aggregates containing various forms of silica materials are very common whereas the latter occurs rarely because of the unsuitability of carbonates for use in concrete. In asr, the reaction is between alkalies and certain siliceous rocks or minerals, such as opaline chert. Alkalisilica reaction in concrete ice virtual library. The product of this reaction is alkalisilica gel, which imbibes water resulting in expansion and subsequently, cracking of concrete. As part of a research project to develop draft specifications for glass in concrete, a major asr testing programme was undertaken to establish appropriate use of glass in concrete which avoided harmful asr. Concrete prism test, astm c 1293 is 1year expansion concrete. Magazine of concrete research, volume 57, issue 1, 1 feb 2005 3947 7 testing aggregates and cementaggregate combinations for their reactivity source. It is often abbreviated, using cement chemists notation, to csh, the dashes indicating that no strict ratio of sio 2 to cao is inferred. Multiaxial expansionstress relationship for alkali silica. This reaction produces a hygroscopic gel, which absorbs water and swells, causing cracking to occur as tension builds in the concrete structure.
A suite of 10 synthetic sodium silica and sodium calcium silica gels was prepared to explore the basic mechanism of expansion of concrete by alkali silica reaction. Alkali aggregate reaction in concrete types, causes, and. Asr is a chemical reaction taking place in concrete between reactive forms of silica in the aggregate and the alkalis in the cement pore solution stanton 1940. For the love of physics walter lewin may 16, 2011 duration. In the presence of moisture, silica reacts with alkalis to form a gel which expands and disrupts mechanical properties during the service life of the concrete structures. Asr involves reactions between alkali pore solution in the concrete and certain forms of alkalireactive silica. Pdf this paper presents a study that used ultrasonic techniques to nondestructively evaluate nde the damage induced by alkali silica reaction asr.
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