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Video showing details of reacting aggregate and X-ray microanalysis of aggregate, gel and cement paste This video is Part 1 of a series of two. In this first video we look at polished sections in the SEM of concrete from a bridge that was demolished due to
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Alkali-silica reaction (ASR) is of more concern because aggregates containing reactive silica materials are more common. 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
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2019-2-4 11. Kishore Kaushal –Alkali-Silica Reaction in Concrete, ICI Bulletin June, 1990, pp. 31-33. We at engineeringcivil are thankful to Er. Kaushal Kishore for submitting the paper on Alkali-Silica Reaction In Concrete. This will be of great help to fellow civil engineers in understanding the Alkali-Silica reaction occurring in concrete.
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2015-10-1 1. Introduction. Alkali–silica 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 silica structure is dissolved by the nucleophilic attack of OH − ions, and the highly degraded silica structure behaves as a hygroscopic silica gel.
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By KAUSHAL KISHORE Materials Engineer, Roorkee The problem of Alkali-silica reaction was believed to be non-existent in India till 1983, when its occurrence was diagnosed in two concrete dams. This paper describes this problem with respect to Indian aggregates and cement. A rapid method of test for alkali-aggregate reaction is investigated and described in the []
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The goal of this paper- to determine the influence of cement type on alkali-silica reaction of mortars with crushed gravel. In the study crushed gravel with fraction 4/16 mm was used and four ...
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🕑 Reading time: 1 minute Alkali aggregate reactions (AAR) occur when aggregates in concrete react with the alkali hydroxides in concrete producing a hygroscopic gel
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Alkali-silica reaction (ASR) is regarded as one of the most deleterious concrete durability problems, known to cause severe deteriorations in reinforced concrete structures all
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2019-2-4 11. Kishore Kaushal –Alkali-Silica Reaction in Concrete, ICI Bulletin June, 1990, pp. 31-33. We at engineeringcivil are thankful to Er. Kaushal Kishore for submitting the paper on Alkali-Silica Reaction In Concrete. This will be of great help to fellow civil engineers in understanding the Alkali-Silica reaction occurring in concrete.
View More
2015-10-1 1. Introduction. Alkali–silica 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 silica structure is dissolved by the nucleophilic attack of OH − ions, and the highly degraded silica structure behaves as a hygroscopic silica gel.
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2020-12-16 Alkali-aggregate reaction (AAR) is a poten-tial distress mechanism for portland cement concrete (PCC) that results from a reaction between alkali hydroxides in the PCC pore solution and reactive aggregates. The most common occurrence of AAR is the alkali-silica reaction (ASR) that results from reac-tions involving specific siliceous aggregates.
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By KAUSHAL KISHORE Materials Engineer, Roorkee The problem of Alkali-silica reaction was believed to be non-existent in India till 1983, when its occurrence was diagnosed in two concrete dams. This paper describes this problem with respect to Indian aggregates and cement. A rapid method of test for alkali-aggregate reaction is investigated and described in the []
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The goal of this paper- to determine the influence of cement type on alkali-silica reaction of mortars with crushed gravel. In the study crushed gravel with fraction 4/16 mm was used and four ...
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Alkali‑silica reaction: understanding the phenomenon Kelvya Maria de Vasc oncelos Moreira 1,2 Paulo V ítor Gomes Oliveira 3 Ênio Pontes de Deus 4 Antônio Eduardo Bezerra Cabral 5
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Alkali-silica reaction (ASR) is regarded as one of the most deleterious concrete durability problems, known to cause severe deteriorations in reinforced concrete structures all around the world.
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🕑 Reading time: 1 minute Alkali aggregate reactions (AAR) occur when aggregates in concrete react with the alkali hydroxides in concrete producing a hygroscopic gel which, in the presence of moisture, absorbs water and causes expansion and cracking over a
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2016-10-12 A better understanding of silica dissolution–precipitation reactions at high pH aqueous solutions allows for promotion of favorable (e.g., pozzolanic) reactions and mitigation of deleterious (e.g., alkali-silica) reactions in concrete. In this paper, the kinetics and products of silica glass dissolution are studied as a function of solution
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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
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2020-12-16 Alkali-aggregate reaction (AAR) is a poten-tial distress mechanism for portland cement concrete (PCC) that results from a reaction between alkali hydroxides in the PCC pore solution and reactive aggregates. The most common occurrence of AAR is the alkali-silica reaction (ASR) that results from reac-tions involving specific siliceous aggregates.
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2021-10-13 According to the American Concrete Institute (ACI) glossary (CT-21 – Concrete Terminology [5]), ASR is a chemical reaction in either mortar or concrete between alkalies (sodium Na + and potassium K +) from portland cement or other sources and certain constituents of some aggregates.
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2021-3-18 Alkali-silica reaction (ASR) is a common form of alkali-aggregate reaction that naturally occurs in concrete. The potential for ASR exists throughout North America because aggregates containing reactive silica are prevalent and often used in concrete mixes. Under conditions of high alkali content cement, reactive aggregates, and
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2021-1-2 Understanding the ASR mechanism is not so simple because it consists of several stages. However, Pan and colleagues [] report that Glasser and Kataoka [14, 15] proposed a simplified two-step description.First, the reaction occurs between the hydroxyl ions (OH −) present in the pores solution of the concrete and the reactive silica of the aggregate.
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The goal of this paper- to determine the influence of cement type on alkali-silica reaction of mortars with crushed gravel. In the study crushed gravel with fraction 4/16 mm was used and four ...
View More
🕑 Reading time: 1 minute Alkali aggregate reactions (AAR) occur when aggregates in concrete react with the alkali hydroxides in concrete producing a hygroscopic gel which, in the presence of moisture, absorbs water and causes expansion and cracking over a
View More
Alkali-silica reaction (ASR) is regarded as one of the most deleterious concrete durability problems, known to cause severe deteriorations in reinforced concrete structures all around the world.
View More
2020-8-25 Balanced alkali limit in cement for alkali-silica reaction risk-free concrete production A thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering (Research) in Civil Engineering by Cibele Sanchez Roboredo to School of Civil and Environmental Engineering Faculty of Engineering and Information Technology
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Alkali–silica reaction (ASR) is the result of a chemical reaction between hydroxyl ions in pore water and silica from aggregates and cement of the concrete matrix.
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2016-10-12 A better understanding of silica dissolution–precipitation reactions at high pH aqueous solutions allows for promotion of favorable (e.g., pozzolanic) reactions and mitigation of deleterious (e.g., alkali-silica) reactions in concrete. In this paper, the kinetics and products of silica glass dissolution are studied as a function of solution
View More