Calorimetric Study into the Role of Alkali and Sulfate in the Early Hydration of Heat-cured GP Cements and Associated Susceptibility to DEF

Martin, L; Thomas, P; Nairn, J; Sirivivatnanon, V

Calorimetric Study into the Role of Alkali and Sulfate in the Early Hydration of Heat-cured GP Cements and Associated Susceptibility to DEF

Martin, L Thomas, P

Nairn, J Sirivivatnanon, V

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Publication Type:: Conference Proceeding
Citation:: 2021
Issue Date:: 2021-09-05

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Field	Value	Language
dc.contributor.author	Martin, L
dc.contributor.author	Thomas, P https://orcid.org/0000-0001-6962-2121
dc.contributor.author	Nairn, J
dc.contributor.author	Sirivivatnanon, V
dc.date	2021-09-05
dc.date.accessioned	2021-11-16T01:09:45Z
dc.date.available	2021-07-01
dc.date.available	2021-11-16T01:09:45Z
dc.date.issued	2021-09-05
dc.identifier.citation	2021
dc.identifier.uri	http://hdl.handle.net/10453/151598
dc.description.abstract	Durability of concrete structures is an important issue in the modern world, with the performance of concrete as a construction material significantly impacting its environmental, economic, and social costs. Understanding of the chemical behaviour of concrete informs the prevention and mitigation of potential causes of durability loss. Delayed e ttringite f ormation (DEF) is a chemical process in concrete that can cause expansion, microcracking and strength loss. It is a known risk of durability loss, in particular with precast concrete. The primary mechanism of DEF is the dissolution of the sulfate mineral ettringite during early hydration and subsequent re-precipitation as an expansive phase in hardened cement paste. The major factors of DEF relate to the saturation of the pore solution with sulfate ions. Primary factors that influence sulfate solubility are alkalinity and temperature, particularly in the early stage of hydration. Factors that influence the ettringite formation are aluminate and sulfate, and their content ratios. DEF is mainly initiated in the manufacturing process of precast elements and is a consequence of phase development during hydration. Isothermal calorimetry provides a way to monitor cement paste hydration and to investigate the role of alkali and sulfate content in phase development. This paper present s the outcomes of a study on the influence of these chemical factors on the hydration process and correlate s this with phase development by characterisation of phases using XRD and TGA in paste compositions that are both DEF free and at-risk of deleterious DEF.
dc.language	en
dc.relation	http://purl.org/au-research/grants/arc/IH150100006
dc.relation.ispartof	Concrete Institute of Australia's Biennial National Conference 2021
dc.rights	info:eu-repo/semantics/openAccess
dc.title	Calorimetric Study into the Role of Alkali and Sulfate in the Early Hydration of Heat-cured GP Cements and Associated Susceptibility to DEF
dc.type	Conference Proceeding
utslib.location.activity	Perth - Virtual
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - CBI - Centre for Built Infrastructure
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Mathematical and Physical Sciences
utslib.copyright.status	open_access	*
pubs.consider-herdc	false
dc.date.updated	2021-11-16T01:09:44Z
pubs.finish-date	2021-09-08
pubs.publication-status	Published
pubs.start-date	2021-09-05

Abstract:

Durability of concrete structures is an important issue in the modern world, with the performance of concrete as a construction material significantly impacting its environmental, economic, and social costs. Understanding of the chemical behaviour of concrete informs the prevention and mitigation of potential causes of durability loss. Delayed e ttringite f ormation (DEF) is a chemical process in concrete that can cause expansion, microcracking and strength loss. It is a known risk of durability loss, in particular with precast concrete. The primary mechanism of DEF is the dissolution of the sulfate mineral ettringite during early hydration and subsequent re-precipitation as an expansive phase in hardened cement paste. The major factors of DEF relate to the saturation of the pore solution with sulfate ions. Primary factors that influence sulfate solubility are alkalinity and temperature, particularly in the early stage of hydration. Factors that influence the ettringite formation are aluminate and sulfate, and their content ratios. DEF is mainly initiated in the manufacturing process of precast elements and is a consequence of phase development during hydration. Isothermal calorimetry provides a way to monitor cement paste hydration and to investigate the role of alkali and sulfate content in phase development. This paper present s the outcomes of a study on the influence of these chemical factors on the hydration process and correlate s this with phase development by characterisation of phases using XRD and TGA in paste compositions that are both DEF free and at-risk of deleterious DEF.

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http://hdl.handle.net/10453/151598