Autogenous shrinkage of a self-compacting VHPC in isothermal and realistic temperature conditions

Title: Autogenous shrinkage of a self-compacting VHPC in isothermal and realistic temperature conditions
Author(s): S. Staquet, C. Boulay, L. D’Aloïa
Paper category : conference
Book title: 2nd International RILEM Symposium on Advances in Concrete through Science and Engineering
Editor(s): J. Marchand, B. Bissonnette, R. Gagné, M. Jolin and F. Paradis
Print-ISBN: 2-35158-003-6
e-ISBN: 2351580028
Publisher: RILEM Publications SARL
Publication year: 2006
Nb references: 14
Language: English

Abstract: The autogenous shrinkage development at early age of a Very High Performance Concrete (VHPC) was analyzed in both situations: under standard isothermal (20°C) conditions and under realistic temperature conditions (same as the precambered steel-VHPC beam investigated in LCPC). Actually, a risk of cracking at very early age due to the transversally restrained shrinkage is probable in this kind of steel-VHPC composite structure (the concrete is cast around the steel girder) and the influence of partly restrained longitudinal shrinkage on the composite behavior is rather significant for the design and behavior of the cross section. The autogenous shrinkage determination was carried out on a new test rig designed in order to start the measurements just after casting. The test rig is immersed in a temperature controlled bath. The displacements of the upper head of the specimen are measured by an external transducer while the specimen is placed vertically. The concrete is placed in a corrugated PVC mold to avoid any friction during the test. The initialization time of the deformations t0, after which shrinkage is considered as effective, is fixed after the observation of the temperature variations in the core of the specimen. In order to use the equivalent age concept, the apparent activation energy Ea of the VHPC was determined experimentally on basis of calorimetric tests. The Speed Method was then applied to compute the apparent activation energy Ea of the VHPC at early age. These experimental investigations have shown that a correct estimation of the VHPC autogenous shrinkage from the realistic temperature histories can be done by using the Equivalent Age Method.

Keywords: Shrinkage, slag, ring test, autogenous, early age

Online publication: 2006-08-02
Classification: 3.2 Theme 2: From Fresh to Hardened Concrete
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2351580028.080