Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux

Type de document

DIRECTION D'OUVRAGE (DO)

Langue

anglais

Auteur

SATO ; TOUTLEMONDE

Résumé / Abstract

ConCrack is a series of international workshops on the control of cracking in concrete structures organized from 2009 by the French Joint Consortium CEOS.fr. ConCrack3, which was the first RILEM-JCI international workshop on early age cracking due to restraint of thermal deformation and delayed ettringite formation (DEF) due to high temperature history in mass concrete structures, was held in Paris on March 15 and 16, 2012. The ConCrack3 proceedings (RILEM PRO 85) were published by RILEM with the support of IFSTTAR as local organizer. JCI's Guidelines for Control of Cracking of Mass Concrete 2008 were also issued for the workshop with the support of IFSTTAR and introduced for the first time in Europe at that time. ConCrack3 is remembered by participants as a unique workshop that singularly advanced the knowledge and practice of control of cracking in concrete structures. Prediction and control of thermal cracking in mass concrete structures with satisfactory accuracy is no easy task as various properties of concrete including creep, shrinkage and tensile strength, which are influenced by stress as well as temperature variations in the process of hydration of cement, have not been fully elucidated. This situation has spurred considerable research in the field of concrete engineering over the years, leading to the revision of JCI's Guidelines for Control of Cracking of Mass Concrete 2008 in 2016. Against this backdrop, it was deemed timely to hold a workshop on issues related to early age cracking in the form of a ConCrack event held by engineers and researchers who are active in this field. Consequently, researchers from IFSTTAR and JCI committee members who contributed to the success of ConCrack3 agreed to hold ConCrack5 in April 2017 in Japan. ConCrack5 consists of two keynote lectures, six invited lectures and twelve general presentations as well as a lecture on JCI's Guidelines for Control of Cracking of Mass Concrete 2016. The written contributions corresponding to the keynote lectures, invited lectures and general presentations are included in the Proceedings. One of the keynote lectures will cover valuable experience in addressing early age issues in large concrete projects. The other keynote lecture will propose a promising numerical simulation concept for the chemical expansion effect in concrete based on the mechanical energy conservation hypothesis, which is applicable to DEF expansion. The six invited speakers will lecture on the following topics: 1) Results of the CEOS.fr. project, 2) DEF coupled to thermal history, 3) Revision of the French recommendations for the prevention of DEF, 4) Progress Report of Mass Concrete Committee of RILEM, 5) Modeling of concrete at early age carried out and 6) Further works on concrete at early age coordinated within COST TU 1404. These invited lectures should give all participants a good understanding of the state of the art in Europe concerning thermal effects on cracking and DEF. Regarding the general presentations, twenty-one abstracts were collected in response to a call for papers. The abstracts were reviewed by three members of the Scientific Committee from the viewpoint of consistency with the Workshop themes, resulting in the acceptance of nineteen abstracts. Eventually, a total of twelve full-length papers were submitted and accepted following review by three members of the Scientific Committee. The full-length papers, along with the keynote lecture papers and invited lecture papers, have been classified into six categories, as follows.1. Thermal Effects at Early Age: Reports from the French CEOS.fr Project, RILEM TC 254-CMS and COST TU 1404, 2. Control of Thermal Effects at Early Age: Materials Approach, 3. Thermal Effects at Early Age: Creep Evaluation, 4. Thermal Effects at Early Age: Prediction of Stress and Crack Width, 5. Control of Thermal Effects at Early Age: Implementation in Real structures, 6. Thermal Effects at Early Age: DEF Prevention. The lectures and general presentations, together with the twenty high-quality articles published in the Proceedings, provide a wealth of information on the most advanced technologies related to thermal effects as well as control of thermal cracking at early age due to hydration heat of cement.

Editeur

Japan Concrete Institute - JCI