Measuring techniques for autogenous strain of cement paste

Pietro Lura, Ole Mejlhede Jensen

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Abstract

Volumetric measurement of autogenous strain is frequently performed by placing the fresh cement paste in a rubber membrane submerged in water. The volume change of the cement paste is measured by the amount of water displaced by the submerged sample. Volumetric and linear measurements of autogenous strain should in principle give identical results. However, the measuring results from the volumetric method are typically 3-5 times higher than the results from the linear technique. In this paper, water uptake from the buoyancy bath through the rubber membrane is identified as the principal artefact of the volumetric method. Water absorption is driven by a lowering of the water activity in the cement paste due to dissolved salts in the pore fluid and to self-desiccation. From the moment of casting, significant water uptake was registered in all experiments. This water uptake influenced the volumetric measurements by the same order of magnitude as the autogenous strain itself. By performing the measurements in a paraffin oil bath instead of a water bath, this artefact was eliminated. Furthermore, volumetric measurements performed in paraffin oil gave almost identical results as linear measurements performed on the same cement pastes.
Original languageEnglish
Title of host publicationKnud Højgaard conference on Advanced Cement-Based materials : Research and Teaching
Volume1
Place of PublicationLyngby, Denmark
PublisherDTU Byg, Danmarks Tekniske Universitet
Publication date2006
Edition1
Pages119-134
Publication statusPublished - 2006
EventKnud Højgaard Conference on Advanced Cement-Based Materials: Research and Teaching - Technical University of Denmark, Kgs. Lyngby, Denmark
Duration: 15 Jun 200515 Jun 2005
Conference number: 1

Conference

ConferenceKnud Højgaard Conference on Advanced Cement-Based Materials
Number1
LocationTechnical University of Denmark
CountryDenmark
CityKgs. Lyngby
Period15/06/200515/06/2005

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