Minimizing alkali leaching in the concrete prism expansion test at 38 °C

Costa, Umberto; Mangialardi, T.; Paolini, A

doi:10.1016/j.conbuildmat.2017.04.116

Cited by 18 publications

(7 citation statements)

References 14 publications

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“…For concrete mixes made with a given aggregate, increasing concrete alkali content (initial Lac) resulted in a little increase of alkali leaching. At a fixed concrete alkali content (Lac = 5.5 kg Na 2 Oeq/m 3 ), the highest percentage alkali release (10.4%) was recorded for the concrete mix made with the most expansive aggregate (aggregate A1) and this was ascribed to crack formation [27] and ASR gel exudation [18]. However, in virtue of the appropriate design of the test apparatus, in particular the low ratio between the net container volume, V nc , and the concrete prism volume, V c (V nc /V c = 2.3), the alkali leaching was always found to be very low (percentage Na 2 Oeq releases of 4.9-11%), as compared to alkali leaching (35-37% Na 2 Oeq releases) reported by Thomas et al [7] using the CSA A 23.2-14A test procedure [8] and by Lindgård et al [28] using the ASTM C1293 test procedure [9].…”

Section: Alkali Leachingmentioning

confidence: 98%

“…The total amounts of alkaline metal ions (Na + + K + ) leached are also reported in terms of alkalis (kg Na 2 Oeq/m 3 concrete), along with the corresponding percentage Na 2 Oeq releases. The leaching data relevant to aggregates A1 and A3 are the same as those published in our previous paper [27] dealing with the alkali leaching from the Portland cement concrete subjected to the traditional CPT.…”

Section: Alkali Leachingmentioning

confidence: 99%

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Assessment of Alkali–Silica Reactivity of Aggregates by Concrete Expansion Tests in Alkaline Solutions at 38 °C

et al. 2020

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A new accelerated concrete prism expansion test at 38 °C (accelerated CPT) is proposed for assessing the alkali-reactivity of concrete aggregates. In this test, concrete prisms with a standardized mix composition and different alkali contents are immersed in alkaline solutions with compositions simulating the pore liquid of hardened concretes. The concrete prism expansion test at 38 °C and RH > 95% (traditional CPT) was taken as a reference test, in order to define the appropriate expansion limit criterion for the proposed accelerated CPT. Three natural aggregates of known field performance and different alkali–silica reactivity were tested. The compositions of alkaline solutions were designed by assuming total dissolution of cement alkalis and taking a ratio between the mass fractions of effective water consumed by cement hydration and of alkalis uptaken by cement hydrates equal to unity. This simplified approach was found in an acceptable agreement with literature empirical equations correlating pore solution alkalinity of hardened Portland cement mixes with total alkali content of cement. Elaboration of expansion data through both pass-fail and threshold alkali level (TAL)-evaluation approaches indicated that, for the accelerated CPT, an expansion limit criterion of 0.04% after 120 days of testing in alkaline solutions is appropriate to evaluate the aggregate alkali reactivity congruently with the traditional CPT. Use of the proposed test method in place of the traditional CPT would reduce the test duration from 365 to 120 days.

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Section: Alkali Leachingmentioning

confidence: 98%

Section: Alkali Leachingmentioning

confidence: 99%

Assessment of Alkali–Silica Reactivity of Aggregates by Concrete Expansion Tests in Alkaline Solutions at 38 °C

et al. 2020

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“…One of the possible reasons that could lead to a discrepancy between the field and the CPT expansions is the excessive alkali leaching from prisms due to their smaller size compared to field samples. Many attempts have been made to reduce the leaching, such as increasing the diameter of the cylindrical samples, increasing the prisms' cross-section or decreasing the air-to-concrete ratio in the testing container [15][16][17]. The increased expansion observed with the cylinders of higher diameter was attributed partly to the lower air-to-concrete ratio compared to smaller diameter samples [15].…”

Section: Introductionmentioning

confidence: 99%

Effect of sample geometry and aggregate type on expansion due to alkali-silica reaction

Sinno

Shehata

2019

Construction and Building Materials

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“…In addition to the aggregate type, some factors could lead to the reduced alkali leaching in the cylinders compared to prisms. First, the lower the volume ratio of air-to-samples will lead to lower alkali leaching as reported by Bérubé, Fournier and Côté (2012) and Costa, Mangialardi and Paolini (2017). In this research, the storage containers were the same for prisms and cylinders.…”

Section: Understanding the Factors Affecting Expansion Of Concrete Due To Asrmentioning

confidence: 75%

“…Thus, the excessive alkali leaching from the prisms is one of the main challenges of CPT. Many attempts have been made to reduce alkali leaching from concrete samples such as increasing the diameter of the cylindrical samples, increasing the prisms' cross-section or decreasing the airto-concrete ratio in the testing container (Bérubé, Fournier and Côté, 2012;Lindgård et al, 2013;Costa, Mangialardi and Paolini, 2017). The increased expansion observed with the cylinders of higher diameter was attributed partly to the lower air-to-concrete ratio compared to smaller diameter samples (Bérubé, Fournier and Côté, 2012).…”

Section: Concrete Prism Testmentioning

confidence: 99%

Development of Enhanced Test Methods to Evaluate Alkalisilica Reaction in Concrete

Sinno¹

2021

Preprint

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Many preventive measures showed improved performance of concrete against alkali-silica reaction (ASR) based on the concrete prism test (CPT) described in the Canadian and American Standards, CSA A23.2-14A and ASTM C1293. However, research has shown that preventive measures that limited the 2-year expansion in the concrete prism test produced late expansion after 7-15 years when tested in the field. The objective of this research is to understand the possible reasons for this late expansion under field conditions and to come up with modified approach to determine the level of supplementary cementing materials (SCM) needed to mitigate the long-term expansion. The research mainly focuses on studying two possible reasons to explain the late expansion. The first reason is the rate and ultimate hydration of SCM, where their capacity to bind alkalis under CPT could be higher than those under field conditions. The other reason for the late expansion could be the geometry and size of the CPT samples which might reduce the expansion due to the excessive alkali leaching. Larger samples showed less leaching compared to standard prisms. 100-mm cylinders showed higher expansion than 75-mm standard prisms; however, both sample shapes showed similar expansions for one tested aggregate when used with SCM. In addition, the capacity of SCM to bind alkalis was shown to be higher at 38ºC compared to the other two tested temperatures investigated in this study: 23ºC and 60ºC. Samples with SCM at high replacement levels expanded more at 60ºC compared to 38ºC. Due to their reduced leaching compared to prisms, testing cylinders at 60ºC showed accelerated results reducing the testing duration to one year compared to the standard test duration of two years. Moreover, a new way to predict the minimum levels of SCM required to mitigate expansion due to alkali-silica reaction is presented showing better correlation with the field. Finally, a fast and reliable test method is suggested to evaluate the reactivity of mineral fillers by adapting and adopting the current test methods available for ASR testing.

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Minimizing alkali leaching in the concrete prism expansion test at 38 °C

Cited by 18 publications

References 14 publications

Assessment of Alkali–Silica Reactivity of Aggregates by Concrete Expansion Tests in Alkaline Solutions at 38 °C

Assessment of Alkali–Silica Reactivity of Aggregates by Concrete Expansion Tests in Alkaline Solutions at 38 °C

Effect of sample geometry and aggregate type on expansion due to alkali-silica reaction

Development of Enhanced Test Methods to Evaluate Alkalisilica Reaction in Concrete

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