Investigation of Alkali Threshold Limits and Blended Aggregate in ASR Risk-Assessed Concretes

Vessalas, K; Nsiah-Baafi, E; Thomas, P; Sirivivatnanon, V

Investigation of Alkali Threshold Limits and Blended Aggregate in ASR Risk-Assessed Concretes

Vessalas, K

Nsiah-Baafi, E Thomas, P

Sirivivatnanon, V

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Publication Type:: Conference Proceeding
Citation:: 2019
Issue Date:: 2019-09-11

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Field	Value	Language
dc.contributor.author	Vessalas, K https://orcid.org/0000-0003-3948-5212	en_US
dc.contributor.author	Nsiah-Baafi, E	en_US
dc.contributor.author	Thomas, P https://orcid.org/0000-0001-6962-2121	en_US
dc.contributor.author	Sirivivatnanon, V https://orcid.org/0000-0003-1901-6064	en_US
dc.date	2019-10-10	en_US
dc.date.available	2019-09-11	en_US
dc.date.issued	2019-09-11	en_US
dc.identifier.citation	2019	en_US
dc.identifier.uri	http://hdl.handle.net/10453/136993
dc.description.abstract	Concrete structures are designed for a specific design life to tolerate deterioration caused from various aggressive environmental loads such as carbon dioxide, chloride and aggressive soil conditions. The approach to prevent deterioration in concrete due to alkali-silica reaction (ASR) is by the avoidance of any such dissolution reaction taking place in concrete. ASR can in part be prevented by limiting the alkali content and restricting the use of potentially reactive aggregates. In this paper, the alkali threshold of several aggregates originating from New Zealand were determined using a modified version of RILEM AAR-3.2 and AAR-7.1. The AAR-2 accelerated mortar bar test (AMBT at 80°C) and AAR-3.2 concrete prism test (CPT at 38°C) were replaced with Australian Standard AS 1141.60.1 and 60.2 test methods, respectively, to evaluate expansion. Additional accelerated CPT in accordance with AAR-4.1 (ACPT at 60°C) was also conducted to examine the adequacy of shortening the test period. Petrographic examination taken before and after expansion testing was also carried out to qualify the presence of reactive silica and ASR gel contributing to expansion. The findings of this study suggest the potential for specifying the alkali threshold in concrete based on the reactivity classification of aggregates allowing a relaxation of the CCANZ Technical Report TR 3 alkali limit of 2.5 kg/m3 that is currently in place in New Zealand. This approach allows greater flexibility in the use of potentially reactive aggregates as sustainable concreting making materials.	en_US
dc.relation	http://purl.org/au-research/grants/arc/IH150100006
dc.relation.ispartof	Concrete New Zealand Conference 2019	en_US
dc.title	Investigation of Alkali Threshold Limits and Blended Aggregate in ASR Risk-Assessed Concretes	en_US
dc.type	Conference Proceeding
utslib.location.activity	Dunedin, New Zealand	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Civil and Environmental Engineering
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences
pubs.organisational-group	/University of Technology Sydney/Strength - CBI - Centre for Built Infrastructure
utslib.copyright.status	open_access
pubs.consider-herdc	true	en_US
pubs.finish-date	2019-10-12	en_US
pubs.publication-status	Published online	en_US
pubs.start-date	2019-10-10	en_US

Abstract:

Concrete structures are designed for a specific design life to tolerate deterioration caused from various aggressive environmental loads such as carbon dioxide, chloride and aggressive soil conditions. The approach to prevent deterioration in concrete due to alkali-silica reaction (ASR) is by the avoidance of any such dissolution reaction taking place in concrete. ASR can in part be prevented by limiting the alkali content and restricting the use of potentially reactive aggregates. In this paper, the alkali threshold of several aggregates originating from New Zealand were determined using a modified version of RILEM AAR-3.2 and AAR-7.1. The AAR-2 accelerated mortar bar test (AMBT at 80°C) and AAR-3.2 concrete prism test (CPT at 38°C) were replaced with Australian Standard AS 1141.60.1 and 60.2 test methods, respectively, to evaluate expansion. Additional accelerated CPT in accordance with AAR-4.1 (ACPT at 60°C) was also conducted to examine the adequacy of shortening the test period. Petrographic examination taken before and after expansion testing was also carried out to qualify the presence of reactive silica and ASR gel contributing to expansion. The findings of this study suggest the potential for specifying the alkali threshold in concrete based on the reactivity classification of aggregates allowing a relaxation of the CCANZ Technical Report TR 3 alkali limit of 2.5 kg/m3 that is currently in place in New Zealand. This approach allows greater flexibility in the use of potentially reactive aggregates as sustainable concreting making materials.

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http://hdl.handle.net/10453/136993