Title:
Use of Triaxial Compression Test on Mortars to Evaluate Formwork Pressure of Self-Consolidating Concrete
Author(s):
Joseph J. Assaad, Jacques Harb, and Kamal H. Khayat
Publication:
Materials Journal
Volume:
106
Issue:
5
Appears on pages(s):
439-447
Keywords:
concrete-equivalent mortar; formwork lateral pressure; selfconsolidating concrete; thixotropy; triaxial testing.
DOI:
10.14359/51663144
Date:
9/1/2009
Abstract:
A comprehensive research project was undertaken to evaluate the suitability of triaxial testing in determining formwork pressure developed by self-consolidating concrete (SCC) under both drained and undrained conditions. The cohesion (C) and angle of internal friction (f) were determined on 10 concrete-equivalent mortar (CEM) mixtures made with various binder types and watercementitious material ratios (w/cm). Correlations were established with respect to thixotropy and formwork pressure determined using SCC. Test results show that the cohesiveness of CEM mixtures is greatly affected by the drained and undrained conditions under which the tests are conducted. Mixtures made with ternary cement and/or lower w/cm exhibited higher C and lower f values compared to those made with binary or Type I cement, as well as those prepared with increased water content. Lateral pressure of SCC developed right after casting can be predicted using either thixotropy or C values. For pressure drop evaluation over time, however, the CEM triaxial approach was not appropriate given the absence of coarse aggregate, which underestimates the development of internal friction between solid particles.