Modelling desiccation shrinkage of large structures

Drying of cement-based materials induces drying shrinkage, which may cause prestress loss or/and cracking if strains are (self or externally) restrained. Drying shrinkage is difficult to predict, since it depends on the material mix, mechanical and hygral boundary conditions, geometry ... This paper focuses on the study of size effect on final drying shrinkage, which is not well documented in the literature. In the Eurocode 2 (European code model), a reduction factor is applied for large structure, which is in agreement with experimental data of one campaign (found in the literature). Using numerical simulations, it is shown that a large panel of models, including phenomenological models as physical ones (which takes into account of (aging) creep under capillary pressure (assumed to be the physical mechanism for drying shrinkage)), do not predict size effect on final value of drying shrinkage.

[1]  J. J. Brooks,et al.  30-year creep and shrinkage of concrete , 2005 .

[2]  Olivier Coussy,et al.  Characterization and identification of equilibrium and transfer moisture properties for ordinary and high-performance cementitious materials , 1999 .

[3]  M.S.J Gan.  Cement and Concrete , 1997 .

[4]  P. Bowen,et al.  Changes in portlandite morphology with solvent composition: Atomistic simulations and experiment , 2011 .

[5]  György Ézsöl,et al.  Nuclear Engineering and Design , 2008 .

[6]  J. Mier,et al.  Experimental investigation of size effect in concrete and sandstone under uniaxial tension , 2000 .

[7]  Bernard Schrefler,et al.  Modelling creep and shrinkage of concrete by means of effective stresses , 2007 .

[8]  Franz-Josef Ulm,et al.  Creep and shrinkage of concrete: physical origins and practical measurements , 2001 .

[9]  Van Genuchten,et al.  A closed-form equation for predicting the hydraulic conductivity of unsaturated soils , 1980 .

[10]  L. Granger.  Comportement différé du béton dans les enceintes de centrales nucléaires , 1996 .

[11]  Farid Benboudjema,et al.  A viscoelastic approach for the assessment of the drying shrinkage behaviour of cementitious materials , 2007 .

[12]  S. E. Pihlajavaara,et al.  A review of some of the main results of a research on the ageing phenomena of concrete: Effect of moisture conditions on strength, shrinkage and creep of mature concrete , 1974 .

[13]  Farid Benboudjema,et al.  Early-age behaviour of concrete nuclear containments , 2008 .

[14]  Olivier Coussy,et al.  ROLE OF AIR PRESSURE IN DRYING OF WEAKLY PERMEABLE MATERIALS , 2001 .

[15]  Véronique Baroghel-Bouny,et al.  Modélisation du séchage des bétons , 2007 .

[16]  Z. Bažant,et al.  Concrete creep at variable humidity: constitutive law and mechanism , 1985 .

[17]  J. Mazars.  A description of micro- and macroscale damage of concrete structures , 1986 .

[18]  Franz-Josef Ulm,et al.  Microprestress-Solidification Theory for Concrete Creep. I: Aging and Drying Effects , 1997 .

[19]  Gert Heshe,et al.  DS/ENV 1992-1-1 NAD. National Application Document for Eurocode 2: Design of Concrete Structures, Part 1-1: General Rules and Rules for Buildings , 1993 .