Creep and shrinkage of heat-cured self-compactiong-concrete (SCC)

Title: Creep and shrinkage of heat-cured self-compactiong-concrete (SCC)
Author(s): D. Chopin, O. Francy, S. Lebourgeois, P. Rougeau
Paper category : conference
Book title: International RILEM Symposium on Self-Compacting Concrete
Editor(s): O. Wallevik and I. Nielsson
Print-ISBN: 2-912143-42-X
e-ISBN: 2912143713
Publisher: RILEM Publications SARL
Publication year: 2003
Pages: 672 - 683
Total Pages: 12
Nb references: 12
Language: English

Abstract: Nowadays, Self-Compacting Concretes (SCC) are widely use in the precast concrete industry. In order to reach high flowability and to maintain sufficient viscosity to prevent segregation, SCC generally contain a higher paste volume than ordinary vibrated concrete. The proportion of paste in SCC usually varies from 32% up to 42% when it is hardly ever superior to 34% in vibrated concrete. The aim of this study is to qualify creep and shrinkage of SCC. As the deformability of the paste can be ten times higher than the one of aggregates, it is generally assumed that the higher the paste volume is, the higher the concrete instantaneous and delayed deformations will be. From this point of view, SCC could show a rather specific behaviour when dealing with creep or shrinkage, which might lead to hold up the development of SCC for the manufacturing of some precast concrete elements such as prestressed beams.
The aim of this study is to bring some concrete elements to settle these interrogations. The first part of the study concerns the qualification of creep and shrinkage of SCC mixes suitable for precast concrete industry. The aim is to quantify the influence of the main parameters (paste volume, gravel/sand ratio, compressive strength, superplasticizer type...). The objective of the second part of the study is to identify the eventual SCC specificities with regard to the French BPEL model. From experimental results obtained during this study, it appears clearly that heat-cured SCC do not show elastic or delayed deformations significantly higher than conventional concretes. Neither the absence of vibrations nor the use of new generation superplasticizers seems to have an influence on the deformability of SCC. This study only treats of SCC which have been heat-cured and loaded at young age. Some complementary tests are necessary to consider if it is possible to extend the conclusions (influence of the different parameters, validity of the models) to the SCC which have not been heat-cured and loaded more belatedly. According to the expectations, the experimental results have confirmed the preponderant influence of some parameters (compressive strength, granular skeleton) on the SCC's behaviour. From experimental results obtained during this study, we can however affirm that a significant difference in paste volume or in G/S ratio does not necessary lead to a difference of behaviour concerning the delayed deformations.
The analysis of the creep models shows that the actual French BPEL model can be very likely apply to the majority of SCC. However, it is preferable to conserve temporarily a security approach in the present state of knowledge. The security coefficients displayed in this study are enough severe to cover the SCC deformations.

Online publication: 2003-08-21
Publication type : abstract_only
Public price (Euros): 0.00