Optimisation of using lightweight aggregates in mitigating autogenous deformation of concrete

Akcay, Burcu; Taşdemi̇r, Mehmet Ali

doi:10.1016/j.conbuildmat.2007.11.015

Cited by 64 publications

(18 citation statements)

References 20 publications

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“…Thus, the amount of replacement of LWAs to mitigate autogenous deformation should be determined with necessary optimization (Akcay and Tasdemir 2008).…”

Section: Autogenous Deformationmentioning

confidence: 99%

Internal curing of mortars by lightweight aggregates and its effects on hydration

Akcay

Taşdemi̇r

2008

Can. J. Civ. Eng.

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This study investigates the effects of lightweight aggregates (LWAs) on heat and degree of hydration in highstrength cementitious materials, in which natural pumice LWAs were used as water reservoirs to provide internal curing for mitigating autogenous deformation. Normal aggregates were substituted by LWAs at three different volume fractions, such as 8%, 16%, and 24% of total volume of mortars. The results show that as the amount of LWAs increased, the autogenous deformation significantly decreased, while the heat of hydration increased slightly. The cement particles can easily find water released from LWAs and consequently, the degree of hydration increased due to internal curing. The addition of LWAs caused a delay in the time to approximately reach the asymptotic value of the nonevaporable water content.Résumé : Cette étude examine les effets des agrégats légers sur la chaleur et le degré d'hydratation dans les liants hydrauliques à haute résistance, dans lesquels des agrégats légers de pierre ponce naturelle ont été utilisés en tant que réservoirs d'eau afin de permettre une cure interne et ainsi atténuer la déformation autogène. Les agrégats normaux ont été remplacés par des agrégats légers selon trois proportions de volume, 8 %, 16 %, et 24 %, par rapport au volume total de mortier. Les résultats ont montré que la déformation autogène diminue grandement en fonction de l'augmentation de la quantité d'agrégats légers, alors que la chaleur d'hydratation augmente légèrement. Les particules de ciment peuvent facilement trouver l'eau libérée par les agrégats légers, permettant ainsi l'augmentation du niveau d'hydratation en raison de la cure interne. L'ajout d'agrégats légers engendre un retard dans le temps approximatif requis pour atteindre la valeur asymptotique du contenu en eau non évaporable.Mots-clés : déformation autogène, degré d'hydratation, chaleur d'hydratation, béton à haute performance, cure interne, agrégat léger.[Traduit par la Rédaction]

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“…Thus, the amount of replacement of LWAs to mitigate autogenous deformation should be determined with necessary optimization (Akcay and Tasdemir 2008).…”

Section: Autogenous Deformationmentioning

confidence: 99%

Internal curing of mortars by lightweight aggregates and its effects on hydration

Akcay

Taşdemi̇r

2008

Can. J. Civ. Eng.

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“…Then, LWAC with 20% UFA (samples 10À13) was chosen to change the water-binder ratio and the pre-wetting state of aggregate, cast the shrinkage specimen and test the autogenous shrinkage rate (Akcay and Tasdemir, 2009;Darquennes et al, 2009) at different ages. The concrete mix proportions and test results of compressive strength at 28 d and are shown in Table 2.…”

Section: Preparation Of Hslwac Containing Fly Ashmentioning

confidence: 99%

Study on early autogenous shrinkage and crack resistance of fly ash high-strength lightweight aggregate concrete

Gao

Zhang

Tang

et al. 2013

Magazine of Concrete Research

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A self-designed test and the elliptical ring test were applied to test the early autogenous shrinkage and crack resistance of fly ash high-strength lightweight aggregate concrete in which 10-30% of cement was replaced by equivalent amounts of fly ash of different fineness. Test data of reference lightweight aggregate concrete were provided. The results showed that (a) the early autogenous shrinkage of concrete was restrained in fly ash highstrength lightweight aggregate concrete, and further analysis indicated higher fly ash content and higher fly ash fineness resulted in less autogenous shrinkage; (b) in a lower water-binder ratio, early autogenous shrinkage increased significantly as the water-binder ratio decreased, and, moreover, pre-wetting of lightweight aggregate had a great effect on controlling early autogenous shrinkage; (c) the elliptical ring test results indicated that the addition of fly ash significantly improved crack resistance of lightweight aggregate concrete and that this improvement becomes obvious with increasing fineness of fly ash. Therefore, in practice, the addition of fly ash could be a technical alternative to reduce early autogenous shrinkage and to enhance the crack resistance of lightweight aggregate concrete.

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“…The replacement of normal aggregate by LWA, even in as small a volume as 10%, can decrease the linear autogenous deformation of concrete. In particular, the replacement of normal aggregate by fine fraction of LWA has been shown to be more effective in reducing the autogenous deformation compared to the use of the coarse fraction of LWAs [1,2].…”

Section: Internal Curing Effectmentioning

confidence: 99%

Affect of lightweight aggregate to early age cracking in concrete

Fenyvesi¹

2011

Per. Pol. Civil Eng.

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.1/B-09/1/KMR-2010-0002). Olivér FenyvesiDepartment of Construction Materials and Engineering Geology, BME, H-1521, Budapest, Hungary e-mail: fenyvesioliver@yahoo.com 1 Introduction 1.1 Early age shrinkage in concrete In concrete, mortar and cement paste shrinkage takes place from the very beginning of the life of the material. This is caused by water movement in the porous and rigid body. During the hydration of cement, while the cement paste is plastic, it undergoes a volumetric contraction (autogenous shrinkage) whose magnitude is of the order of one per cent of the absolute volume of dry cement. However, the extent of hydration prior to setting is small, and once a certain stiffness of the system has developed, the contraction induced by the loss of water by hydration is greatly restrained [38]. Withdrawal of water from concrete, mortar or cement paste stored in unsaturated air causes drying shrinkage. A part of this drying shrinkage is irreversible and should be distinguished from the reversible moisture movement caused by alternating storage under wet and dry condition [24,38].Influencing factors of early age shrinkage in mix design:

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Optimisation of using lightweight aggregates in mitigating autogenous deformation of concrete

Cited by 64 publications

References 20 publications

Internal curing of mortars by lightweight aggregates and its effects on hydration

Internal curing of mortars by lightweight aggregates and its effects on hydration

Study on early autogenous shrinkage and crack resistance of fly ash high-strength lightweight aggregate concrete

Affect of lightweight aggregate to early age cracking in concrete

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