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Viscoelastic stress modeling in cementitious materials using constant viscoelastic hydration modulus

Hansen, W. and Liu, Z. and Koenders, E. A. B. (2014):
Viscoelastic stress modeling in cementitious materials using constant viscoelastic hydration modulus.
DCMat Ageing Centre, Delft University of Technology, In: 1st Ageing of Materials & Structures Conference, Delft, The Netherlands, 26-28 May 2014, ISBN 9789461863,
[Online-Edition: http://resolver.tudelft.nl/uuid:6f2fe376-15f1-423b-b8a1-9699...],
[Conference or Workshop Item]

Abstract

Viscoelastic stress modeling in ageing cementitious materials is of major importance in high performance concrete of low water cement ratio (e.g. w/c ~0.35) where crack resistance due to deformation restraint needs to be determined. Total stress analysis is complicated by the occurrence of internal stresses due to shrinkage, which requires estimating the stress relaxation effect from tensile creep. This study presents a new and direct methodology for viscoelastic stress analysis based on measurement of the viscoelastic hydration modulus. Autogenous shrinkage, if restrained, creates an internal tensile stress condition which is uniform within a cross section. Autogenous shrinkage stresses develop within the porous hydration products. They are compressive stresses and if restrained by reinforcement a net tensile stress develops. Results show that the viscoelastic hydration modulus is approximately 8000-9000 MPa and is a constant material property. Total stress analysis can now be separated into two components, an elastic stress based on the Young’s modulus (typically in the range of 28000-34000 MPa) and a viscoelastic (time-dependent) stress based on measurement of timedependent strains (creep and shrinkage). The importance of reducing paste content for shrinkage stress control is demonstrated using the Pickett’s model.

Item Type: Conference or Workshop Item
Erschienen: 2014
Creators: Hansen, W. and Liu, Z. and Koenders, E. A. B.
Title: Viscoelastic stress modeling in cementitious materials using constant viscoelastic hydration modulus
Language: English
Abstract:

Viscoelastic stress modeling in ageing cementitious materials is of major importance in high performance concrete of low water cement ratio (e.g. w/c ~0.35) where crack resistance due to deformation restraint needs to be determined. Total stress analysis is complicated by the occurrence of internal stresses due to shrinkage, which requires estimating the stress relaxation effect from tensile creep. This study presents a new and direct methodology for viscoelastic stress analysis based on measurement of the viscoelastic hydration modulus. Autogenous shrinkage, if restrained, creates an internal tensile stress condition which is uniform within a cross section. Autogenous shrinkage stresses develop within the porous hydration products. They are compressive stresses and if restrained by reinforcement a net tensile stress develops. Results show that the viscoelastic hydration modulus is approximately 8000-9000 MPa and is a constant material property. Total stress analysis can now be separated into two components, an elastic stress based on the Young’s modulus (typically in the range of 28000-34000 MPa) and a viscoelastic (time-dependent) stress based on measurement of timedependent strains (creep and shrinkage). The importance of reducing paste content for shrinkage stress control is demonstrated using the Pickett’s model.

Publisher: DCMat Ageing Centre, Delft University of Technology
ISBN: 9789461863
Uncontrolled Keywords: autogenous shrinkage, High Performance Concrete (HPC), modeling viscoelastic effects, shrinkage stresses
Divisions: 13 Department of Civil and Environmental Engineering Sciences
13 Department of Civil and Environmental Engineering Sciences > Institute of Construction and Building Materials
Event Title: 1st Ageing of Materials & Structures Conference
Event Location: Delft, The Netherlands
Event Dates: 26-28 May 2014
Date Deposited: 04 Jun 2015 08:44
Official URL: http://resolver.tudelft.nl/uuid:6f2fe376-15f1-423b-b8a1-9699...
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