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Materials 2018, 11(8), 1393; https://doi.org/10.3390/ma11081393

Alkali Release from Aggregates in Long-Service Concrete Structures: Laboratory Test Evaluation and ASR Prediction

1
Ricerca sul Sistema Energetico (RSE S.p.A.), Via R. Rubattino 54, 20134 Milano, Italy
2
Department of Chemical Materials Environment Engineering, Faculty of Civil and Industrial Engineering, La Sapienza University, 00184 Roma, Italy
*
Author to whom correspondence should be addressed.
Received: 18 July 2018 / Revised: 6 August 2018 / Accepted: 7 August 2018 / Published: 9 August 2018
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Abstract

This paper proposes a simple model for predicting the development of deleterious expansion from alkali-silica reaction (ASR) in long-service concrete structures. This model is based on some composition and reactivity parameters related to ASR, including the long-term alkali contribution by aggregates to concrete structures. This alkali contribution was estimated by means of a laboratory extraction test, appositely developed in this study in order to maximize the alkali extraction within relatively short testing times and with low leaching solution/aggregate ratios. The proposed test is a modification of the Italian Standard test method UNI 11417-2 (Ente Nazionale Italiano di Normazione) and it consists of subjecting an aggregate sample to leaching with saturated calcium hydroxide solution in a laboratory autoclave at 105 °C. Nine natural ASR-susceptible aggregates (seven sands and two coarse aggregates) were tested and the following optimized test conditions were found: leaching solution/aggregate weight ratio = 0.6; solid calcium hydroxide/aggregate weight ratio = 0.05; test duration = 120 h. The results of the optimized alkali extraction tests were used in the proposed model for predicting the potential development of long-term ASR expansion in concrete dams. ASR predictions congruent with both the field experience and the ASR prevention criteria recommended by European Committee for Standardization Technical Report CEN/TR 16349:2012 were found, thus indicating the suitability of the proposed model. View Full-Text
Keywords: alkali-silica reaction; concrete aggregates; long-term alkali release; alkali extraction test; ASR prediction model alkali-silica reaction; concrete aggregates; long-term alkali release; alkali extraction test; ASR prediction model
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Berra, M.; Mangialardi, T.; Paolini, A.E. Alkali Release from Aggregates in Long-Service Concrete Structures: Laboratory Test Evaluation and ASR Prediction. Materials 2018, 11, 1393.

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