Civilax is the knowledge base covering all disciplines in civil engineering. Pdf alkalisilica reaction and microstructure of concrete subjected. Alkaliaggregate reaction portland cement association. The use of lithium to prevent or mitigate alkalisilica reaction in concrete pavements and structures. We aim to close the gap to the industry by improving the awareness about latest trends in civil engineering. Alkalisilica reactivity, better known as asr, has openly been with us since the early1940s when it was discovered in california and publicized by t. Report on the diagnosis, prognosis, and mitigation of alkalisilica reaction asr in transportation structures. Alkaliaggregate reaction aar is a reaction in concrete between the alkali hydroxides, which originate. The effects of supplementary cementitious materials on. 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. Alkalisilica reaction in concrete civil engineering. I briefly appraise the problems and trends in aar research in the pacific northwest region. Civil engineering department the university of texas at austin david fowler, ph. It occurs when the alkaline pore fluid and siliceous minerals in some aggregates react to form a calcium alkali silicate gel.
Asr is a chemical reaction between the reactive silica in the aggregate and the alkalis na2o and k2o in. Diagnosis and control of alkaliaggregate reactions in concrete. Fiore colorado state university north dakota state university south dakota state university university of colorado denver university of denver university of utah utah state university university of wyoming. Asr can cause expansion and subsequent cracking of concrete, thus compromising its durability by. Alkalisilica reaction, testing procedures, aggregates. Technical note tn 030 alkali slica reaction in concrete vicroads. This usually occurs between the highly alkaline portland cement and the various siliceous substances contained in the aggregate. Risk of alkalisilica reaction when using recycled concrete aggregate in new concrete mpc 15302 j. The susceptibility of alkaliactivated fly ash and slag concrete binders to deleterious asr was evaluated in accordance with relevant astm standards. The influence of relative humidity rh, temperature. The distress of the reinforced concrete is a result of the presence of three.
Alkalisilica reaction asr is a deleterious reaction between the alkaline pore solution of concrete and various metastable forms of silica contained in many natural and synthetic aggregates. The use of surplus waste glass in concrete has been avoided on the grounds that it is known to undergo harmful alkalisilica reaction asr. The alkalisilica reaction forms a gel that swells as it draws water from the surrounding. The chemistry of this reaction is complex 1 multistaged 2 and is essentially an. Factors affecting asr for alkalisilica reaction to occur, three conditions must be present. Length change of concrete due to alkalisilica reaction. Development of an ultraaccelerated test to evaluate asr.
Alkalisilica reaction in portland cement concrete the university. Alkali silica reaction asr is of more concern because aggregates containing reactive silica materials are more common. Topics on alkalisilica reaction development bureau. Modified asr test astm c 1260 method with weight, volume. Progress in the evaluation of alkaliaggregate reaction in. A gelatinous product is formed which imbibes pore fluid and.
Alkali silica reaction asr is a significant problem in cheyenne and other towns because of the presence of reactive aggregates. Chapter 2 alkalisilica reaction guidelines for the use. Pdf research of alkali silica reaction in concrete with. Development of an ultraaccelerated test to evaluate asr potential in concrete. Alkalisilica reaction asr is one of the most recognized durability problems in concrete leading to premature deterioration of different types of concrete structures. Alkali silica reaction asr in cement free alkali activated. Effects of moisture, temperature, and freezing and thawing on. The distress caused by alkali silica reaction asr to concrete structures can occur long time. A human cancer, if untreated is terminal, whereas the alkalisilica reaction and the expansion it induces, if untreated, eventually stops. The influenceof relative humidity rh, temperatur e, wettinganddrying wd, and ft on the development of asr were evaluated herein. 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. Alkalicarbonate reaction in concrete was not documented until. Construction standard on aggregates for concrete cs3, draft. Engineering properties of concrete affected by alkali.
Alkalisilica reaction asr is the most common form of alkaliaggregate reaction. The alkalisilica reaction in concrete civil engineering. Alkalisilica reaction asr and freezing and thawing ft deteri oration reduce the service life of concrete. In other words, higher percentages of the same materials may be needed in concrete made with rca. Significant expansion due to alkalisilica reaction has occurred in the concrete made with highalkali portland cement used as a control but has not been observed in any of the ternary blend mixtures. The term premature concrete deterioration pcd has been adopted to refer to problems. Ai 2 o 3 perspective 10 aspire summer 2018 overview of delayed ettringite formation and alkalisilica reaction delayed ettringite formation def and alkalisilica reaction asr are complex mechanisms that can significantly diminish the durability and service life of concrete elements. The use of lithium to prevent or mitigate alkali silica reaction in concrete pavements and structures. Pdf investigation of alkalisilica reaction in concretes with. Alkalisilica reaction, or asr, is a chemical combining of reactive silica from concrete aggregate with the alkali from cement paste in the presence of moisture.
Report on the diagnosis, prognosis, and mitigation of. 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. Part i of this report is a synthesis of our knowledge of mechanisms of damage to concrete by alkalisilica reactivity. The great majority of cases of concrete structures reported as showing deterioration due to alkalisilica reaction were made using highalkali cement.
This gel absorbs water, producing a volume expansion which can disrupt the concrete. Notes b, c, d, and e apply to the portland cement concrete bde special provision which includes alkalisilica reaction mitigation requirements for castinplace, precast, and precast prestressed concrete. The silica structure is dissolved by the nucleophilic attack of oh. Mitigation of alkalisilica reaction in volcanic aggregate. Preventing alkalisilica reaction and delayed ettringite. Mitigation of alkali silica reaction in volcanic aggregate concrete using pfa and ggbs annual concrete seminar 2016 20 april 2016 ryan c. Mandatinguse of class f fly ash limiting alkali content of cement existing concrete ne continues to resurface or rebuild affected concrete pavements alkali silica reaction asr. Dr jason eidiker of oregon state university presents his research on alkali silica reaction of concrete. New concrete national and state specific research and development has eliminated asr concerns in todays concrete mixes through. The expansive reactions between alkalis and alkali reactive aggregates within concrete. Alkalisilica reaction in concrete containing glass. The alkalisilica reaction though not true is described as a concrete cancer. No concreted structure or part of a concrete structure any where in the world has collapsed due to alkalisilica reaction alone.
Alkaliaggregate reaction aar is only one of the many factors that might be fully or partly responsible for the deterioration and premature loss in serviceability of concrete infrastructure. From the many different damage mechanisms that can originate the deterioration of concrete, alkalisilica reaction asr is the. A detailed study of the effects of alkalisilica reaction asr on the engineering properties of concrete such as compressive and tensile strength, elastic modulus, and pulse velocity is presented. Alkalisilica reaction asr study of the asr potential of aggregates from geological point of view study of asr in hardened concrete from geological point of view c. The alkalisilica reaction asr is the most general form of aar. The result of the reaction is a gel, which can expand and may cause microcracks in concrete. Over seven decades later, occurrences of this reaction may actually be increasing, despite our vast knowledge about asr gained over these years.
Two types of reactive aggregatea naturally occurring beltane opal and a synthetic fused silicawere used. Risk of damaging alkalisilica reaction the concrete society. This experiment used locallysourced materials such as aggregates and admixtures in order to develop a concrete mix that will give the optimum resistance to such combined action. Alkalisilica reaction and delayed ettringite formation. Astm international and equivalent aashto documents related to alkaliaggregate. Recent investigation into premature deterioration of airfield concrete pavements indicated the aggressive effects of alkaliacetate and alkaliformate based deicers on concrete containing marginal aggregates, in particular on. Also, asr resistance of alkali activated fly ash and slag concrete was compared to that of ordinary portland cement concrete opc while.
Alkalisilica reaction gels are composed of twocomponent mixtures of alkalicalciumsilicate hydrate and alkalisilica sols of nearly fixed compositions. Alkaliaggregate reaction aar is a reaction in concrete between the alkali hydroxides, which. Effects of moisture, temperature, and freezing and thawing. Pdf the alkalisilica reaction asr in concrete occurs by reaction of certain silica phases in the aggregates with alkalis and hydroxide ions in the. A the r value, an indicator of the relative sulfate resistance of a fly ash, is a ratio of calcium to iron oxide. 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. It was discovered that concrete made with rca exhibits lower expansions due to alkalisilica reaction asr than the original concrete made with natural aggregates. Alkalicarbonate reaction in concrete and its implications. This report summarizes the findings of an experimental evaluation into alkali silica reaction asr in cement free alkaliactivated slag and fly ash binder concrete.
Nacl deicer is the most often used brine in polish climatic zone. Shear tests on beams cut from asraffected bridge decks. Alkalisilica reactivity asr occurs either in mortar or concrete. Alkalisilica reaction asr and freezing 3and thawing ft deteri oration reduce the service life of concrete. Previous work has shown, however, that these materials are not as effective at mitigating asr in concrete made with rca compared to concrete made with natural aggregates. Civil engineering department the university of texas at austin and ramon carrasquillo, ph. The effects of alkalisilica reaction on the mechanical properties of. Alkali load reactive aggregate moisture cement so 4. Although alkali activated cement has received worldwide attention due to its lower energy consumption and environmental impact than that of traditiona. Concrete technology diagnosis and control of alkali. This reaction produces a hygroscopic gel, which absorbs water and swells, causing cracking to occur as tension builds in the concrete structure.
Alkalicarbonate reaction in concrete and its implications for a high rate of longterm compressive strength increase. Concrete alkali silica reaction presentation youtube. In asr, aggregates containing certain forms of silica will react with alkali hydroxide in concrete to form a gel that swells as it adsorbs water from the surrounding cement paste or the environment. The first round of testing utilized a nonlaboratory created rca and the second evaluated two wyoming concretes prepared with black rock and knife river aggregates respectively. The alkalisilica reaction asr is a major factor contributing to concrete infrastructure aging surpassed only by rebar corrosion induced by depassivation and as such, is widely studied. Factors affecting asr for alkali silica reaction to occur, three conditions must be present. Perspective overview of delayed ettringite formation and.
Alkalisilica reaction asr and delayed ettringite formation def, or combinations of the two, have been found to be the main causes of these problems. These factors exac erbate concrete deterioration,and understanding theelationship r. Question on alkalisilica reaction the concrete society. Effect of combined asr and cyclic loading on concrete bridges. A deleterious chemical reaction between hydroxyl oh ions associated with alkalis sodium and potassium present in cement or other sources and certain reactive siliceous components that may be present in coarse or fine aggregates, produces a gel. 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. Testing methods and mitigation alternatives by wissam touma, ph. This chapter provides an overview of the fundamentals of asr in concrete. The use of lithium to prevent or mitigate alkalisilica. Pdf salt solutions are used to ensure safe driving conditions during winter. For asr to occur in its damaging form, sufficient alkalinity of the pore water solution hydroxyl ion concentration must be present to react with certain forms of silica in the aggregate to form a gel.
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