Pdf salt solutions are used to ensure safe driving conditions during winter. Chemistry of the alkaliaggregate reaction f p glasser. Processes for making cement which when used to make concrete can stabilize the concrete against alkali silica reactivity asr from alkali containing components. Alkalisilica reaction and delayed ettringite formation. A process in which silica found in aggregate in the presence of moisture, is broken down by alkalis found in cement produces an expansive gel. Alkalisilica reaction asr is a chemical reaction between the alkalis in portland cement and certain types of silica minerals present in some aggregates. 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. The chemical reaction can result in abnormal expansion and cracking of concrete. This reaction produces a hygroscopic gel, which absorbs water and swells, causing cracking to occur as tension builds in the concrete structure. Cracking may be initiated by swelling of aggregate particles before copious production of gel and large expansions of cracks caused by swelling of gel occurs. Alkali silica reactivity, alkali aggregate reaction, reactive aggregates, concrete durability, concrete, prescriptive, preventive, control, pp65.
Astm c1567 standard test method for determining the. Chapter 2 alkalisilica reaction guidelines for the use of. Under certain circumstances, the formation of the gel can cause expansion and, eventually, cracking of the. High replacement levels of slag cement in properly proportioned mixes also help control shrinkage, creep and thermal cracking in mass concrete structures. Alkalisilica reaction in concrete detailed guidance for new construction. Role and effectiveness of mineral admixtures in relation to alkali silica reaction r n swamy. Processes for making cement which when used to make concrete can stabilize the concrete against alkalisilica reactivity asr from alkali containing components. Alkali silica reaction an overview sciencedirect topics. The reference center has been organized for quick and easy access to various resources, and will be updated regularly to ensure that the most uptodate information is available. The susceptibility of alkali activated fly ash and slag concrete binders to deleterious asr was evaluated in accordance with relevant astm standards. Mar 21, 2019 alkali silica reaction asr asr is a chemical combining of reactive silica from the concrete aggregate with the alkali from the cement paste in the presence of moisture. The alkalisilica reaction in concrete 1st edition r n. Engineered for longterm durability, newcem slag cement helps structures achieve greater strength potential, reduced permeability, and increased resistance to sulfate attack and alkali silica reaction.
Alkali silica reaction asr asr is a chemical combining of reactive silica from the concrete aggregate with the alkali from the cement paste in the presence of moisture. The expansion increasing with the decreasing aggregate size can be reproduced by the proposed model. Asr is the most common form of alkali aggregate reaction aar in concrete. The chemical reaction can result in abnormal expansion and cracking of. From the many different damage mechanisms that can originate the deterioration of concrete, alkali silica reaction asr. The result of the reaction is a gel, which can expand and may cause microcracks in the concrete. Alkalisilica reaction danish experience s chatterji, z. No concreted structure or part of a concrete structure any where in the world has collapsed due to alkali silica reaction alone. As the alkalinity of the pore solution increases, the potential for alkalisilica reaction increases as more stable forms of silica become susceptible to attack van dam et al. Alkali silica reaction asr can cause serious expansion and cracking in concrete, resulting in major structural problems and sometimes necessitating demolition. A method using concentrated aqueous solutions of sodium cobaltinitrite and rhodamine b is described which can be used to identify concrete that contains gels formed by the alkalisilica reaction asr. There has been an enormous amount of literature about the background theory and cases of alkalisilica reaction in concrete structures after its discovery by stanton in california, usa in 1940. Alkali aggregate reaction is a an umbrella term for two types of premature concrete deterioration.
Alkali silica reaction asr is a chemical reaction between the alkalis in portland cement and certain types of silica minerals present in some aggregates. Introduction to alkaliaggregate reaction in concrete a b poole. Alkalisilica reaction article about alkalisilica reaction. As the alkalinity of the pore solution increases, the potential for alkali silica reaction increases as more stable forms of silica become susceptible to attack van dam et al. Standard test method for potential alkalisilica reactivity. Masterlife asr 30 admixture meets astm c 494c 494m requirements for type s, specific performance, admixtures. Pdf ultrasonic nondestructive evaluation of alkali.
Pdf investigating the alkali silica reaction of recycled. The result is an alkali silicate gel that absorbs water and swells if in a moist environment. Wed like to understand how you use our websites in order to improve them. Alkali silica reaction alkali silica reaction asr in concrete is a reaction between certain silicious constituents in the aggregate and the alkali sodium and potassium hydroxide which are released during the hydration of portland cement. Us5739035a detection of alkalisilica reaction swelling in. Alkalisilica reaction asr is a deleterious chemical reaction occurring in all types of structures that contain alkalireactive aggregates. The result is an alkalisilicate gel that absorbs water and swells if in a moist environment. Thomas, diego lazama, sulapha peethamparon clarkson university utrc, the city college of new york 7th street and convent ave. Despite numerous studies published, the mechanism is not yet clearly understood. Pdf this paper presents a study that used ultrasonic techniques to nondestructively evaluate nde the damage induced by alkali silica reaction asr. Alkalisilica reaction asr prohibitinguse of class c fly ash. The reaction involves interaction of hydroxyl ions associated with alkali in cement with certain siliceous constituents of the aggregate reactive silica the products of reaction such as sodium silicate gel called water glass form on the exterior surface of particles and can bring about excessive expansion, cracking, pop outs and general. 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.
The alkalisilica reaction in concrete 1st edition, kindle. A method using concentrated aqueous solutions of sodium cobaltinitrite and rhodamine b is described which can be used to identify concrete that contains gels formed by the alkali silica reaction asr. Alkalisilica reactivity asr asr concrete materials. Alkalisilica reaction gels are composed of twocomponent mixtures of alkalicalciumsilicate hydrate and alkalisilica sols of nearly fixed compositions. The reference center was developed to provide users with access to pertinent information related to alkalisilica reactivity asr. Us6022408a cement and concrete compositions for controlling. Lithuanian quarry aggregates concrete effects of alkaline corrosion tests lietuvos karjeru uzpildu poveikio betono sarminei korozijai tyrimai. The asr mechanism and mitigation of asr within portland cement. Alkalisilica reaction and high performance concrete. Chemistry of the alkali aggregate reaction f p glasser. Alkali silica reaction asr in cement free alkali 121916 activated sustainable concrete zihui li, robert j. Role and effectiveness of mineral admixtures in relation to alkalisilica reaction r n swamy. It is a chemical reaction that involves the alkali ions in pore solution in cement paste and the reactive silica of concrete structure aggregates 1. Alkalisilica reaction in concrete detailed guidance for.
Alkalisilica reaction asr is an expansive damage mechanism which occurs when reactive silica phases in certain aggregates combine with alkalis available. Aggregates constitute about threequarter of the volume of concrete, and therefore their physical and chemical properties need to be correctly assessed before their use in concrete. Calculation of alkali silica reaction asr induced expansion before. This chapter provides an overview of the fundamentals of asr in concrete. Use of doublelayer theory to explain the behavior of reactionproduct gels. The alkali silica reaction though not true is described as a concrete cancer. The mechanism of deterioration is known as alkali aggregate reaction aar. Civil engineering department the university of texas at austin david fowler, ph.
The reference center was developed to provide users with access to pertinent information related to alkali silica reactivity asr. Alkalisilicate reaction in cement silicon dioxide concrete. If only the nonswelling gel is formed, the reaction is benign to the concrete. Alkalisilica reaction asr is a frequent cause of reduced concrete durability. This is a short introduction to asr for more information, see the understanding cement bookebook. Since the 1940s, considerable research has been developed to. Damage due to alkali silica reaction asr in concrete is a phenomenon that was first recognized in the u. The basic mechanisms of asr are summarized, followed by discussions on asr manifestations and symptoms in field structures, relevant test methods, methods of preventing asr, and specifications. Alkali silica reaction in concrete simplified guidance for new construction using normal reactivity aggregates. Mitigation of alkalisilica reaction in pavement patch. 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 august 2009 35 codes and standards bre digest 330. Under adverse conditions, the volume of the alkali silicate gel may gradually expand to such an extent as to cause localised swelling pressure. Alkalisilica reaction in concrete a book for concrete users which provides an authoritative explanation of the alkalisilica reaction asr, its effects and methods of minimizing the risk of danger in new construction.
The expanding gel creates tensile forces, causing the concrete to crack. The term premature concrete deterioration pcd has been adopted to refer to problems associated with asr and def because it is often difficult to distinguish between them. In the last few decades, the alkalisilica reaction asr has been. Topics on alkalisilica reaction development bureau.
This report summarizes the findings of an experimental evaluation into alkali silica reaction asr in cement free alkali activated slag and fly ash binder concrete. Kishore kaushal alkalisilica reaction in concrete, ici bulletin june, 1990, pp. Civil engineering department the university of texas at austin and ramon carrasquillo, ph. It is based on the accelerated test method developed at the national building research institute. This field identification handbook provides guidance in identifying alkali silica reactivity asr in concrete field structures, such as bridges and pavements.
Alkalisilica reaction takes place between alkalis na 2 o and k 2 o from cement or other sources and certain reactive silica minerals present in the coarse or fine aggregates. Testing methods and mitigation alternatives by wissam touma, ph. The silicic acid h 2 sio 3 or sio 2 is simply replaced in the reaction by the carbonic acid h 2 co 3 or co 2. Alkaliaggregate reaction is a an umbrella term for two types of premature concrete deterioration. Nacl deicer is the most often used brine in polish climatic zone. Alkali silica reaction the influence of calcium on silica dissolution and the formation of reaction products, journal of the american ceramic society 94. A human cancer, if untreated is terminal, whereas the alkali silica reaction and the expansion it induces, if untreated, eventually stops. The alkalisilica reaction asr, more commonly known as concrete cancer, is a swelling reaction that occurs over time in concrete between the highly alkaline cement paste and the reactive noncrystalline silica found in many common aggregates, given sufficient moisture this reaction causes the expansion of the altered aggregate by the formation of a soluble and. These forms of deterioration encompass a chemical reaction between certain aggregate types and the host cement paste, most importantly the internal pore solution in.
Sufficient alkali reactive silica eactive grega alkalies in pore solution eactive ggrega si02 alkalies breakdown aggregate and release reactive silica asr gel alkalies silica reacts with alkalies and absorbs water to produce expansive asr gel sufficient moisture. Bhupinder singh, in waste and supplementary cementitious materials in concrete, 2018. Alkali silica reaction danish experience s chatterji, z fordos and n thaulow. Alkali silica reaction article about alkali silica. The process includes adding lithium containing materials in the front of a cement kiln along with the cement starting materials in an amount sufficient to minimize asr. Alkalisilica reaction and high performance concrete by ferraris, chiara f. Practices to mitigate alkalisilica reaction asr affected. No concreted structure or part of a concrete structure any where in the world has collapsed due to alkalisilica reaction alone. Alkali silica reaction asr is a deleterious chemical reaction occurring in all types of structures that contain alkali reactive aggregates. These solutions present little health or environmental risk, are readily applied, and rapidly discriminate between two chemically distinct gels. Alkali silica reaction gels are composed of twocomponent mixtures of alkali calciumsilicate hydrate and alkali silica sols of nearly fixed compositions. Masterlife asr 30 lithium based, liquid admixture is formulated for use in high alkali concrete containing reactive aggregates to inhibit and control alkali silica reactivity asr. Alkalisilica reaction asr is a material degradation mechanism that occurs in concrete structures. The alkali silica reaction mechanism catalysed by a soluble strong base as naoh or koh in the presence of caoh 2 alkalinity buffer present in the solid phase can be compared with the carbonation process of soda lime.
The alkalisilica reaction though not true is described as a concrete cancer. Alkalisilica reaction in concrete civil engineering. Micromechanical modelling for the prediction of alkali. You will receive an email with a link to your publication after completing the. 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. Selecting measures to prevent deleterious alkalisilica. At its interface with cement paste, glass shows evidence of pozzolanic reaction which leads to the formation of nonexpansive csh. The reaction product is a hygroscopic gel, which absorbs moisture and swells. Alkali aggregate reaction, commonly known as aar, is the chemical reaction in either mortar or concrete between the hydroxyl oh ions associated with alkalis, sodium na and potassium k, naturally present in portland cement, or from alternative sources with reactive silica present in coarse or fine aggregate. The use of surplus waste glass in concrete has been avoided on the grounds that it is known to undergo harmful alkalisilica reaction asr.
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. Alkalisilica reaction in concrete containing glass. Nevertheless, the three major factors in concrete have been identified, i. Proper models to monitor asr is a major concern for concrete. Two interlaboratory studies were performed utilizing recycled concrete aggregate rca in accordance with astm c1260 accelerated mortar bar test ambt in. The handbook also provides fundamental information about asr, including the requirements for asr to take place and the chemical reaction that leads to the formation of asr gel. This document is available to the public through the national technical information service, springfield, va 22161.
Alkalisilicareaction asr is a result of reaction between the alkalinepore solution and reactive silica in the aggregate. Us5739035a detection of alkalisilica reaction swelling. The alkalisilica reaction results in the production of 2component gels. Then you can start reading kindle books on your smartphone, tablet, or computer. Pdf alkalisilica reaction and microstructure of concrete subjected. This usually occurs between the highly alkaline portland cement and the various siliceous substances contained in the aggregate. Alkali silica reaction in concrete a book for concrete users which provides an authoritative explanation of the alkali silica reaction asr, its effects and methods of minimizing the risk of danger in new construction. The reactionleads to the formation of a gel which absorbs water and expandsleading to damaging expansions and cracking in the concrete. Enter your mobile number or email address below and well send you a link to download the free kindle app.