Effect of cement substitution by limestone on the hydration and microstructural development of ultra-high performance concrete (UHPC)

Wei Huang, Karen Scrivener, Wei Sun
Elsevier, 2017
Article

The effect of limestone on the hydration and microstructural development of ultra high performance concrete (UHPC) with different levels of replacement (34%, 54% and 74% by volume) was investigated. Up to 54% replacement of cement by limestone the mixes showed better workability and higher compressive strength (170 MPa at 56 days for 54% addition) compared to a classical mix (155 MPa) with no limestone replacement. The kinetics of hydration were compared for different replacement levels using isothermal calorimetry. The phase development was quantified by X-ray diffraction with Rietveld method combined with thermal gravimetric analysis. The pore structure was examined by mercury intrusion porosimetry. The composition of hydration products was determined by scanning electron microscopy with energy dispersive X-ray analysis. The results showed that the hydration degree of the cement is increased from 39% for classical UHPC to 66% for the UHPC with 54% of limestone. (C) 2016 Elsevier Ltd. All rights reserved.

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Concepts associés

Chargement

Publications associées

Chargement

Wei Huang, Karen Scrivener, Wei Sun
Elsevier, 2017
Article

Résumé

Official source

https://infoscience.epfl.ch/record/226869?ln=fr

À propos de ce résultat

Concepts associés (14)

Concepts associés

Chargement

Publications associées (40)

Publications associées

Chargement

Alite-ye'elimite clinker: Hydration kinetics, products and microstructure

Xuerun Li, Karen Scrivener, Ruben Anton Snellings

This paper presents the hydration kinetics, products and microstructure of an alite-ye'elimite clinker containing 4 wt% of ye'elimite to boost the early strength development. Isothermal calorimetry, X-ray diffraction, backscattered scanning electron microscopy and mercury intrusion porosimetry were used to study the hydration processes. The results showed that the ye'elimite phase hydrated very rapidly, before the main hydration of alite, forming ettringite as main hydration product. The ye'elimite hydration products precipitated throughout the pore space and reduced the microporosity of the hardened paste at early age. The presence of ye'elimite strongly affected the early hydration before 24 h of hydration, but did not show a significant effect on the hydration kinetics or products at later ages. (C) 2020 Elsevier Ltd. All rights reserved.

ELSEVIER SCI LTD2021

Chargement

Impact of Annealing on the Early Hydration of Tricalcium Silicate

Amélie Bazzoni, Marco Cantoni, Karen Scrivener

It was recently proposed that the induction period observed during the hydration of tricalcium silicate could be explained by the build-up of ions in solution. Due to the importance of defects in this mechanism, this work describes the effect of different annealing effects on the defect structure and hydration behavior of C3S. The impact of annealing on the crystal structure was checked by X-ray diffraction and the defect structure studied by transmission electron microscopy. The hydration kinetics were followed by isothermal calorimetry of pastes. Scanning electron microscopy was used to look at the microstructure formation. It was observed that grinding created a highly deformed layer on the surface of the grains, which disappeared after annealing. The defect structure was closely related to the length of the induction period observed in pastes by calorimetry. There was no observable effect on the morphology of C-S-H during hydration, but the number of calcium hydroxide nuclei was less in pastes from annealed material.

Wiley-Blackwell2014

Chargement

Cement substitution by a combination of metakaolin and limestone

Mathieu Antoni, John Espen Rossen, Karen Scrivener

This study investigates the coupled substitution of metakaolin and limestone in Portland cement (PC). The mechanical properties were studied in mortars and the microstructural development in pastes by X-ray diffraction, thermogravimetry analysis, mercury intrusion porosimetry and isothermal calorimetry. We show that 45% of substitution by 30% of metakaolin and 15% of limestone gives better mechanical properties at 7 and 28 days than the 100% PC reference. Our results show that calcium carbonate reacts with alumina from the metakaolin, forming supplementary AFm phases and stabilizing ettringite. Using simple mass balance calculations derived from thermogravimetry results, we also present the thermodynamic simulation for the system, which agrees fairly well with the experimental observations. It is shown that gypsum addition should be carefully balanced when using calcined clays because it considerably influences the early age strength by controlling the very rapid reaction of aluminates. (C) 2012 Elsevier Ltd. All rights reserved.

Pergamon-Elsevier Science Ltd2012

Chargement

Ciment

vignette|Du ciment, fourni en sac, prêt à être mélangé avec de l’eau et des granulats. Le ciment est un liant hydraulique (qui durcit sous l'action de l'eau), utilisé dans la préparation du béton, et

Microscopie électronique à balayage

Essai de compression

Un essai de compression mesure la résistance à la compression d'un matériau sur une machine d'essais mécaniques suivant un protocole normalisé. Les essais de compression se font souvent sur le même ap