Influence of Cavities on the Structural Performance of Compressed Earth Brick Masonry: A Parametric Comparison of Various Cavity Shapes and Sizes

The use of masonry, and particularly of geo-sourced materials like
compressed earth bricks, has been generating growing interest. These materials
represent an alternative to cementitious products such as concrete, thereby reduc
ing the demand for cement. For this substitution to be fully effective, improving
their mechanical performance remains a crucial challenge. Although several stud
ies have been conducted on the brick scale, the improvement of the masonry
structure may be achieved through the improvement of mortar joints and their
interface with the brick. One of the best ways to ensure perfect adhesion of inter
faces is to produce full bricks with cavities such that the wet mortar takes the
shape of the cavity and anchors itself in the brick as it hardens. Such cavities can
influence the global behaviour of masonry. The common shape of the cavity in the
CEB is trapezoidal and is located only at the middle top of the brick. This study
aims to investigate the real added value of these cavities and to study the influence
of the different shapes and sizes of the cavities on masonry behaviour. To achieve
this objective, an experimental study and numerical simulations were conducted.
In the first approach, a push-out test was performed on triplets formed using bricks
without cavities. This first approach allowed to obtain interface parameters such
as cohesion and coefficient of friction. The same test was performed numerically
using triplets formed by bricks with different cavities. In this second approach, a
total of 12 bricks were designed with different shapes and sizes of cavities. The
results showed different distributions of stress at the interface with a concentration
near the joint protrusions.