Active and non-active porosity in concrete Part I: Experimental evidence

Yaman, İsmail; Hearn, Nataliya; Aktan, Haluk

doi:10.1007/bf02482109

Cited by 132 publications

(77 citation statements)

References 10 publications

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Section: Discussionsupporting

confidence: 82%

“…In particular, the reduction of Ed attained for the mortar I-065 was significantly greater than those obtained for the mortar I-040 and I-045. These results further enforce the conclusion that the reduction of modulus upon loss of moisture is dominated by capillary porosity Yaman, Hearn, Aktan, & Yaman, 2002).On other hand, after rewetting the mortar samples during 24 hours, Ed values were consistently lower than those obtained in pristine state. The restoration of internal moisture in concrete was pointed out as an irreversible process.…”

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confidence: 80%

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Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability

Fernández¹,

Nuno²

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Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability "Estudio del comportamiento no lineal de ondas mecánicas para la caracterización de materiales basados en cemento y su durabilidad" July 2016Autor: Jesús Nuño Eiras Fernández Directores:Jordi Payá Bernabeu John S. PopovicsQuiero expresar mi agradecimiento a mi tutor Jordi Payá por sus acertadas directrices durante la elaboración de esta tesis, por haberme dado la oportunidad de trabajar en este proyecto e iniciarme en la carrera investigadora. Extiendo este agradecimiento al resto del equipo: Mercedes Bonilla, Victoria Borrachero, José Monzó, Ana Mellado y Lourdes Soriano, que con su buen hacer han contribuido a la construcción de un grupo de reconocido prestigio. A mis compañeros con los que he compartido horas en las aulas, laboratorio, y en discusiones de diferente índole: Mauro Tashima (el Special thanks are given to Tribikram Kundu who actively collaborated during the course of this project, and for advice and helpful discussions during the analysis of experimental results. Also, for hosting me during a short stay at University of Arizona.Also thanks are given to Umar Amjad, Ehsan Mahmoudabadi, Ajoy Kumar Das, and Abdullah Al-Hussein for good friendship and helpful discussions during my stay at UA.Special thanks are also given to John S. Popovics, for helpful advice and guidance, and for thoughtful discussions during the course of the PhD. Also, for hosting me and supervising my work at University of Illinois at Urbana-Champaign. I want to extend these thanks to those with whom I shared time in the laboratory at UIUC, preparing samples, No voy a olvidar en estas últimas líneas a mi familia. A mis hermanos Juan y Bárbara, y mis sobrinos Bárbara y Xosé. A Sandra quien ha sido mi apoyo en las buenas y en las malas. Por último, voy a dedicar la tesis a mi madre quien me ha apoyado de forma incondicional y se ha esforzado para ofrecerme siempre lo mejor, y a mi padre, a quien siempre está presente en mi corazón y sé que está conmigo en todo momento.[…] Ring the bells that still can ring, Forget your perfect offeringThere is a crack in everything That's how the light gets in.from Anthem, Leonard Cohen. ResumenLas construcciones de hormigón deben ser diseñadas para perdurar en el tiempo manteniendo su integridad mecánica y sus condiciones de servicio durante la vida útil para la que han sido proyectadas. A este respecto, la evaluación del hormigón y sus constituyentes tanto en laboratorio como en ensayos in situ es, por tanto, esencial para garantizar las condiciones de servicio requeridas al hormigón. El ensayo de determinación de las frecuencias de resonancia ha sido tradicionalmente empleado para determinar la integridad mecánica de testigos de hormigón, en la evaluación de la conformidad de mezclas de hormigón en diversos ensayos de durabilidad, y en la terminación de propiedades constitutivas como son el módulo elástico y el factor de amortiguamiento. Las condiciones del ensayo de determinación de las frec...

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Section: Discussionsupporting

confidence: 82%

supporting

confidence: 80%

Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability

Fernández¹,

Nuno²

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“…Then the capillary porosity (also named active porosity [265]) and their connection will be minimal, increasing strength and durability.…”

Section: Watermentioning

confidence: 99%

“…However, it is proved that high workability reduces the content of entrained/entrapped air (also named non-active porosity) [206] [265] and then increases the compressive strength, so the water reduction is limited to obtain a fluidity that allows the air rising. Then, as UHPFRC is selfcompacting, a compromise solution has to be chosen for the water content in order to keep low both the content of capillary and entrapped air.…”

Section: Watermentioning

confidence: 99%

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Dosage optimization and bolted connections for UHPFRC ties

Camacho¹,

Efraím²

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No part of this volume may be produced, stored in retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publishers. Los límites son físicos. Las limitaciones, mentales. Summary Dosage optimization and bolted connections for UHPFRC tiesConcrete technology has been in changeful evolution since the Roman Empire time. It is remarkable that the technological progress became of higher magnitude from the second part of the XX Century. Advances in the development of new cements, the appearance of the fibers as a reinforcement for structural applications, and specially the grand progress in the field of the water reducing admixtures enabled the emergence of several types of special concretes. One of the lasts is the Ultra High Performance Fiber Reinforced Concrete (UHPFRC), which incorporates advances of the Self-Compacting Concrete (SCC), Fiber-Reinforced Concrete (FRC) and Ultra High Strength Concrete (UHSC) technology. This exclusive material requires a detailed analysis of the components compatibility and a high control of the materials and processes. Mainly patented products have been used for the few structural elements carried out so far today, but the costs makes doubtful the development of many other potential applications.In accordance with the previously explained, a simplification of the UHPFRC components and processes is needed. This becomes the first main goal of this Ph.D. thesis, which emphasizes in the use of local available components and simpler mixing processes. Moreover, the singular properties of this material, between ordinary concrete and steel, allow not only the realization of slenderer structures, but also the viability of new concepts unthinkable with ordinary concrete. In this field is focused the second part of the Ph.D. thesis, which develops a bolted connection system between UHPFRC elements. This research summarizes, first of all, the subfamilies belonging to the HPC-UHPC materials. Afterwards, it is provided a detailed comparison between the dosage and properties of more than a hundred of mixtures proposed by several authors in the last ten years of technology. This becomes a useful tool to recognize correlations between dosages and properties and validate or no preconceived ideas about this material.Based on this state of art analysis was performed the later development of mixtures, on Chapter 4, which analized the effect of use of simpler components and processes on the UHPFRC. The main idea was use local components available in the Spanish market, identifying the combinations that provide the best rheological and mechanical properties. Steam curing use was avoided since a process simplification is intended. Diferent dosages were developed to be adapted to various levels of performance, and always trying to be as economical as possible. The concretes designed were selfcompacting and mainly combined two fiber types (hybrid), as the flexural performance was of greater relevanc...

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