Threshold alkali contents for expansion of concretes containing British aggregates

Sibbick, R.G.; Page, Christopher

doi:10.1016/0008-8846(92)90123-d

Cited by 21 publications

(8 citation statements)

References 1 publication

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“…This pH-value corresponds to a certain alkali threshold that several have reported to exist for initiating and sustaining ASR in concrete [20]. No "absolute" limit is defined, because the critical alkali content largely depends on the aggregate reactivity [21]. For most alkali-reactive aggregates, the alkali threshold when applying CEM I cements in 38ºC concrete prism tests (CPTs) is in the range 3-5 kg Na 2 O eq per m 3 concrete, but may be lower for some rapidly reactive aggregates.…”

Section: Technical Backgroundmentioning

confidence: 99%

Alkali–silica reactions (ASR): Literature review on parameters influencing laboratory performance testing

Lindgård

Andiç‐Çakır

Fernandes

et al. 2012

Cement and Concrete Research

274

154

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Utilization of potentially alkali-silica reactive aggregates requires reliable performance tests to evaluate the alkali-silica reactivity of various aggregate combinations, including their alkali threshold dependence on binder type. Several such performance tests have been used worldwide for more than 15 years, but none of the methods have proven to be reliable for use with all aggregate types and all binders. One of the objectives of RILEM TC 219-ACS (2007-2012) is to develop and validate one or more of such performance tests. Several parameters may influence the results obtained in an accelerated performance test compared to the field behavior. Based on a state of the art literature review, this paper discusses which parameters must be considered to be able to develop reliable ASR performance testing methods and provides some tentative recommendations. The internal humidity in the test specimens, the extent of alkali leaching and the storage temperature are of particular importance.

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Section: Technical Backgroundmentioning

confidence: 99%

Alkali–silica reactions (ASR): Literature review on parameters influencing laboratory performance testing

Lindgård

Andiç‐Çakır

Fernandes

et al. 2012

Cement and Concrete Research

274

154

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“…5, if using a concrete with a Na2O content less than 3kg/m 3 in the presence of chalcedony, a typical aggregate with intermediate reactivity, it will result in a negligible reaction. [6] External alkalis such as deicing salts or airborne salt in marine environments do not generally contribute significantly to the total alkali content and do not increase the risk of ASR given the slow rate of penetration into the concrete. [7]…”

Section: Alkali Contentmentioning

confidence: 99%

“…Behaviour of concrete with reactive aggregate containing chalcedony as a function of Alkali content [6]. …”

mentioning

confidence: 99%

ASR: Practical investigative techniques and field monitoring systems used to assess ASR for service life modeling.

Matteini¹,

Noyce²,

Crevello³

2019

MATEC Web Conf.

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Alkali Silica Reaction (ASR) is a common deterioration mechanism affecting many concrete structures of any type and age. Initially identified more than 60 years ago (Stanton, 1930), this mechanism is based on the chemical reactions between certain siliceous minerals present in the aggregate and the alkalinity of the concrete in the presence of moisture (internal RH). While certain deterioration patterns are clearly associated with ASR, such as gel exudation, aggregate expansion, and characteristic cracking, the material degradation can often be misdiagnosed to the untrained eye. In addition, certain elements of a structure can be severely affected while neighboring elements of the same batch/ mix design do not bear signs of deterioration or impact. Thus far, in situ field monitoring of ASR affected structures is related to moisture measurements, electrical resistivity, expansion, service life models are based on fracture mechanics of the aggregate. The impact to the concrete is loss of integrity, decreased compressive strength, shear and tensile strength. Some observed structures have split, with such force, that the concrete structure had cracks greater than 25mm where steel retention bands have split. The authors of this paper were engaged in two instances to provide service life assessments for ‘corrosion related degradation’ on ASR affected structures. In all instances the elements which were assessed were structural, load bearing elements, which if failed could pose a significant risk to owner, user, or end recipient. The need to develop an assessment technique for monitoring and service life assessments which are practical and efficient is being developed. The paper will discuss the development of the approach, from visual indicators identifying condition hierarchies, to long term condition monitoring for various concrete parameters combined with laboratory testing (expansion and residual alkalis) and mathematical modeling. Three case studies will be presented to illustrate conditions and process.

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“…As far as the alkali content is concerned, two categories can be distinguished: the alkali content provided by cement and the one from external sources. For both cases, the reaction is accelerated and the measurement of free expansion shows higher values when the alkali content is higher (Kawamura et al., 1988; Sibbick and Page, 1992; Smaoui et al., 2005). Several studies also show that in very high alkali contents, the gel structure changes and loses its swelling capability (Kagimoto et al., 2014).…”

Section: Introductionmentioning

confidence: 97%

Effect of alkali silica reaction on the mechanical properties of aging mortar bars: Experiments and numerical modeling

Pathirage

Bousikhane

D'Ambrosia³

et al. 2018

International Journal of Damage Mechanics

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Alkali silica reaction and its effect on concrete and mortar have been studied for many years. Several tests and procedures have been formulated to evaluate this reaction, particularly in terms of aggregate reactivity. However, the data given in the literature concerning the mechanical properties of concrete and mortar are scattered and very little information is available for some properties such as fracture energy. In this study, the mechanical behavior of mortar was evaluated and monitored, under normal and accelerated environmental conditions. Fracture energy, compressive strength and tensile strength were measured for mortar specimens, casted with highly reactive Spratt crushed aggregate, at two different storage temperatures (23℃ and 80℃) and at two different alkali concentrations (immersed in water and in 1 N NaOH solution). Moreover, free expansion tests (according to ASTM C1260) and petrographic observations were performed, in order to relate them to the evolution of the mechanical properties of mortar. Results show a decrease of the mechanical properties associated with specimens at 80℃ in alkali solution and that the deterioration due to alkali silica reaction is counter-balanced by the strengthening of mortar resulting from the hydration process. A multi-physics computational framework, based on the Lattice Discrete Particle Model is then proposed. Numerical simulations based on a complete calibration and validation with the obtained experimental data capture the behavior of mortar subjected to the complex coupled effect of strength build-up and alkali silica reaction at different temperatures and alkali contents.

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Threshold alkali contents for expansion of concretes containing British aggregates

Cited by 21 publications

References 1 publication

Alkali–silica reactions (ASR): Literature review on parameters influencing laboratory performance testing

Alkali–silica reactions (ASR): Literature review on parameters influencing laboratory performance testing

ASR: Practical investigative techniques and field monitoring systems used to assess ASR for service life modeling.

Effect of alkali silica reaction on the mechanical properties of aging mortar bars: Experiments and numerical modeling

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