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Title: Early Age Cracking in Cementitious Systems Edited by K. Kovler and A. Bentur ISBN: 2-912143-29-2 e-ISBN: 2351580362 Pages: 398 Publication date: 2003 Order this book |
Early age cracking sensitivity is a well-known phenomenon, which is associated with drying shrinkage. In special structures and concretes this can be aggravated by thermal effects. The cracking sensitivity induced by drying can occur before or at the onset of setting (plastic shrinkage cracking) or at the period of few days after beginning of setting and hardening. The traditional methods to deal with this problem include the application of proper curing procedures (sealing or water ponding) and the preparation of contraction joints in slabs and pavements.
The advent of modern concrete technology renewed the interest in this issue from several points of view: application of new means to control cracking (e.g. fiber reinforcement and shrinkage reducing admixtures) and the development of a variety of new concretes of superior performance in the fresh and hardened state, that may be more sensitive to early age cracking (e.g. high strength concretes of low water/binder ratio).
In order to optimize the use and design with such concretes and admixtures, there is a need for a comprehensive understanding and treatment of early age cracking. Such an approach is much more complex than the simplistic treatment where cracking sensitivity is quantified in terms of free shrinkage only. It is essential to evaluate, test and model the systems under restrained conditions, to take into account the stresses developed and assess the risk of cracking by considering fracture criteria.
With this in mind, the RILEM technical committee TC 181-EAS was established, to develop and advance the required comprehensive treatment outlined above, to cover basic mechanisms, engineering and design considerations, as well as testing procedures. The current symposium was one of the activities sponsored by this committee. It was intended to bring together international experts dealing with this variety of topics as a step for synthesis of the different complementing approaches to the issue of early age