80. An old approach to determine ‘time zero’ (to) in SCC and its variance in self-stress evaluations

Title: 80. An old approach to determine ‘time zero’ (to) in SCC and its variance in self-stress evaluations
Author(s): K. Imamoto
Paper category : conference
Book title: 5th International RILEM Symposium on Self-Compacting Concrete
Editor(s): G. De Schutter and V. Boel
Print-ISBN: 978-2-35158-047-9
e-ISBN: 978-2-35158-088-2
Publisher: RILEM Publications SARL
Publication year: 2007
Pages: 533 - 538
Total Pages: 6
Nb references: 5
Language: English

Abstract: In this paper, we investigate the ‘time zero’ (To) values of reinforced self-compacting highstrength concrete. Several methods have been proposed to determine To, such as the mechanical penetration method, electrical testing, ultrasonic measurements and so on. The heat evolution method is an old approach to determine the initial setting time (close to To) of cementitious systems and provides information only about hydration kinetics. On the other hand, from the viewpoint of developing a practical approach, the heat evolution method can be applied to construction sites, because the hydration kinetics and structural developments of cementitious systems correlate with each other. We discussed the changes in the autogenous shrinkage strain and the shrinkage-induced stresses from To determined by the heat evolution method with respect to two types of concrete specimens. The test results indicate that although the influence of the variance in To on the autogenous shrinkage strain determined by this simple method is significant, the influence on the shrinkage-induced stress will be mitigated due to the early-age development of concrete creeps. Further, we show that a step-by-step stress analysis with or without the variance in To effectively simulates the stress development in reinforced concrete.

Online publication: 2009-06-16
Publication type : full_text
Public price (Euros): 0.00