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Capabilities and limitations

Title: Capabilities and limitations
Author(s): Ø. Bjøntegaard, E.J. Sellevold
Paper category : conference
Book title: International RILEM Symposium on Concrete Science and Engineering: A Tribute to Arnon Bentur
Editor(s): J. Weiss, K. Kovler, J. Marchand, and S. Mindess
Print-ISBN: None
e-ISBN: 2912143926
Publisher: RILEM Publications SARL
Publication year: 2004
Nb references: 32
Language: English

Abstract: Test equipment has been developed to measure stress build-up in hardening concrete in the laboratory. The Temperature-Stress testing machine (TSTM) is a very useful instrument that can be used for a variety of purposes, and the following issues are discussed in the paper: Description of the TSTM at NTNU (denoted the Stress Rig), stress-inducing deformations, centricity of loading, E-modulus and tensile strength, deduced creep and relaxation, direct creep testing and reproducibility. The main points to be aware of from our experience are the following two: (1) Tensile strength is about 20% lower than that of direct tensile tests. The problem is inherent to the particular TSTM and hence must be quantified for each given machine if the tensile strength is to be measured. (2) The incremental E-modulus displays a strong dependence on the size of the strain-step provided by the feedback system, and seems to produce scatter even with large step-sizes. Thus, thorough investigations must be carried out before such E-modulus data can be used in calculations. We notice that most TSTM-curves are for isothermal conditions. We therefore stress the point that in realistic cases, it is not possible to extrapolate isothermal conditions to variable temperatures.

Online publication: 2004-03-25
Classification: Plastic Shrinkage
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143926.004

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