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Paper category : Proceedings
Book title : JCI-RILEM International Workshop on
Control of Cracking of Mass Concrete and Related Issues
concerning Early Age Cracking of Concrete Structures
Published by the Japan Concrete Institute
ISBN : 978-4-86384-084-3-C3050
Publication year : 2017
Pages : 1-210
Language : English


Abstract: Preface

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. Moreover, the ConCrack5 Workshop will provide participants with unique opportunities to exchange valuable information through fruitful discussions.
JCI’s Guidelines for Control of Cracking of Mass Concrete 2016, which will also be introduced in the workshop, systemize the control methods for thermal cracking and prevention methods for DEF cracking. The fact that JCI’s Guidelines for Control of Cracking of Mass Concrete 2016 provide quantitative limit values for verification should make them applicable across the globe notwithstanding diverse concrete materials and climate conditions.
ConCrack5 will be held on April 24-26, 2017 in Tokyo. It is the first JCI-RILEM international workshop focusing on thermal cracking as well as DEF prevention in mass concrete structures to be held in Japan, and it will feature speakers from six countries: Belgium, Canada, France, Japan, Portugal and the USA.
ConCrack5 is co-organized by JCI and IFSTTAR in partnership with RILEM. We would like to express our sincere gratitude to all the authors, speakers and chairpersons involved for their invaluable contributions to the Workshop, as well as to the members of the Organizing Committee and the Scientific Committee and the chiefs and members of the four task groups of the Local Organizing Committee for their dedicated efforts in preparing the Workshop. We also wish to acknowledge the institutions that supported the organization of ConCrack5: JCI, IFSTTAR and RILEM, as well as the Obayashi Foundation, which provided financial support.
Furthermore, our appreciation also goes to the ten organizations taking part in the technical exhibition, for displaying their own technologies related to thermal cracking and contributing to financial support of the Workshop. Finally, we owe our deepest gratitude to Dr. Tsutomu KANAZU, the Secretary General of the Organizing Committee, Toshiaki MIZOBUCHI, the Chairman of the Scientific Committee, and Shingo ASAMOTO, member of the Scientific Committee, for their distinguished contributions to the organization of the Workshop and their initiative in reviewing and editing all the papers featured in the Proceedings.
It is our sincere hope that all the participants to the ConCrack5 Workshop will find it enjoyable and enriching, and will go on to apply the latest information related to control technologies of thermal effects in concrete to their own work.

April 2017 in Tokyo, Japan
Ryoichi SATO, François TOUTLEMONDE


Online publication : 2017
Publication type : full_text
Public price (Euros) : 0.00