ISSN: 2165-3984
CODEN: ACEMF9
Published Online: 1 September 2012
Page Count: 18

---

Assessment of Thixotropy of Fresh Mortars by Triaxial and Unconfined Compression Testing

Assaad, Joseph J.
Professor of Civil Engineering, R&D Manager, Holderchem Building Chemicals, Baabda, Yarze

Harb, Jacques
Associate Professor, Chair, Civil Engineering Dept., Notre Dame Univ., Louaize,

(Received 30 November 2011; accepted 27 April 2012)

Abstract

Triaxial and unconfined compression tests are widely used in geotechnical applications to analyze soil’s shear strength properties, including its cohesion (C) and angle of internal friction (ϕ). A research program was undertaken to evaluate the suitability (advantages and limitations) of such tests for assessing the thixotropy of freshly mixed mortars. Validation of the results was achieved via the establishment of correlations between thixotropy and various static stability indexes, including water bleeding, surface settlement, and coarse aggregate segregation. The test results show that variations in structural build-ups (or thixotropy) can be detected well using triaxial and unconfined compression tests. Testing is realized under quasi-static conditions, with which the discrepancies related to rotational speed and resting periods prior to shearing in mortar rheometers can be eliminated. Tests conducted under drained conditions yielded higher C values than those realized under undrained conditions, indicating that water drainage increases the rate of restructuring (or thixotropy) of cementitious-based materials. A cohesion threshold of around 4kPa was detected on tested mortars, below which the use of such tests becomes inappropriate.

Keywords:
triaxial compression, unconfined compression, cohesion, thixotropy, fresh mortars

Paper ID: ACEM104469
DOI: 10.1520/ACEM104469
ASTM International is a member of CrossRef.

Author Title Assessment of Thixotropy of Fresh Mortars by Triaxial and Unconfined Compression Testing Symposium , 0000-00-00 Committee C09