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Abstract
Mechanical behavior of structures made from cementitious materials has been successfully
modeled using nonlinear fracture mechanics in recent decades. On the structural scale,
an assumption of homogeneity of the material is valid and well established theories can be
applied. However, if focus is put on phenomena of a similar scale as is the characteristic
size of inhomogeneities of the material, a model which re
ects the heterogeneous nature
of the material needs to be applied. This is, indeed, the case for prediction of mechanical
properties of a material based on the knowledge of properties of its constituents and
composition or when focus is put on a single crack and an accurate estimation of its
width.
Similarly, in the case of ordinary portland cement paste, a simple relationship linking
the strength of the cement paste with its porosity was proposed and widely used for
a long time. However, in today's blended cements, systems with higher porosity and
higher strength at the same time are often found. Thus, the arrangement of the phases in
microstructures plays an important role. These microstructures are highly heterogeneous
and a model for prediction of mechanical properties of the materials needs to be able to
take this complexity into account.
In this thesis, two frameworks for prediction of strengths of cementitious materials are
developed. The rst one relates the strength of materials with aggregates with the properties
of the matrix and distribution of aggregates. The second one relates the strength
of cement paste with the properties of cement phases and its microstructure. The frameworks
consist of an experimental part, an identication of material properties from the
experiments and a modeling part based on an approximative discrete particle model.
In the case of mortar and concrete, it is demonstrated that the measured modeI
fracture properties of the matrix together with tted ratios of modeI to modeII properties
are sucient to provide estimations of modeI, mixedmode and compressive experiments
matching favorably experimental records.
In the case of pure cement paste, it is experimentally observed and numerically veried
that the cracking plays an important role in modeI as well as compressive experiments.
The approximative particle model extended for materials with heterogeneous matrices
predicts strengths matching favorably experimental records in a qualitative way.
Original language  English 

Place of Publication  Kgs. Lyngby, Denmark 

Publisher  Technical University of Denmark 
Number of pages  151 
ISBN (Print)  9788778773111 
Publication status  Published  2010 
Fingerprint Dive into the research topics of 'Fracture propagation in cementitious materials: Multiscale approach: measurements and modeling'. Together they form a unique fingerprint.
Projects
 1 Finished

Fracture Mechanics for Cement Paste and Mortar: Measurement and Modeling
Skocek, J., Stang, H., Kabele, P., Olesen, J. F., Brühwiler, E. & Karihaloo, B.
01/09/2006 → 10/11/2010
Project: PhD