Compressive strength evolution in early-age Portland Cement paste predicted by a micromechanical model

Title: Compressive strength evolution in early-age Portland Cement paste predicted by a micromechanical model
Author(s): B. Pichler, C. Hellmich, J. Eberhardsteiner
Paper category : conference
Book title: International RILEM Symposium on Concrete Modelling - ConMod '08
Editor(s): E. Schlangen and G. De Schutter
Print-ISBN: 978-2-35158-060-8
e-ISBN: 978-2-35158-076-9
Publisher: RILEM Publications SARL
Publication year: 2008
Pages: 139 - 146
Total Pages: 8
Nb references: 23
Language: English

Abstract: Early-age stiffness and strength evolution of cement paste is studied in the framework of continuum micromechanics. Based on the self-consistent scheme, elastic and strength properties are upscaled from the scale of several micrometers up to the scale of several hundreds or thousands of micrometers. The newly proposed strength model is based on a von Mises-type elastic limit criterion for individual hydrates. Corresponding deviatoric stress peaks within hydrates are estimated through quadratic stress averages. In this way, the micromechanical strength criterion is formulated in terms of macroscopic loading (stresses or strains, respectively). Model-predicted elasticity and strength evolutions are compared with data from experimental testing of cement pastes with water-cement ratios ranging from 0.35 to 0.60. Satisfactory agreement between model predictions and experiments allows for two conclusions: The morphology of hydrates significantly influences micromechanics-based elastic stiffness estimates of cement paste particularly at very early ages, whereas elastic properties of mature cement paste can be estimated reliably on the basis of either spherical or acicular shaped hydrates. The development of a reliable strength model, however, requires consideration of hydrates as non-spherical particles, no matter what age of cement paste is considered.

Online publication: 2009-06-15
Publication type : full_text
Public price (Euros): 0.00