Geotechnical News December 2010
59
GEO-INTEREST
Mud Bricks and Shred Geogrids as
Sustainable Material
Hamed Niroumand
Klodiana Millona
Abstract. This session presents a survey
and the performance of the role of shred
geogrids in mud brick’s compressive
strength and a comparison of it with
the normal mud bricks. Mud brick
consists of clay, water and different
materials. Its massive use may become
an important evaluation due to its low
cost and higher compressive strength
compared to the concrete blocks. Many
experiments conducted on earth blocks
without any addition material, report
about its low compressive strength.
Thus, many testing on the strength
of the mud brick, with different
additional materials were done. These
different additions may be shred tires,
which consist in narrow strips of
rubber. Another material is the shred
geogrids, which consists in polyester
strips grid. The paper articulates
the change of compressive strength
of mud bricks with these different
additional materials. This is evident
in the compressive test days 3,7,14
and 21 where the results show that
due to different bricks with normal
mud bricks and shred geogrids with
sizes of 10cm×10cm×10cm, have 20%
moisture content. The tires are one of
the materials that cause environmental
pollution and it is used less after
consumption in the automotive
industry, thus we used a cheap material
for surveying the strength in mud
brick. As well the geogrids are used
in soil stabilization, where they have
additional pieces in construction, so we
used them in mud bricks. The results
show that performances of mud bricks
with shred geogrids were better than
normal mud bricks.
Keywords:
Mud Brick, Shred
geogrid, Comprehensive strength, Sus-
tainable material
Introduction
Mud bricks should ideally be made
with earth containing a clay content of
not more than 80% and not less than
50%, the reminder being sand and
granular material. At this stage, it is
helpful to have a general idea about
the crystal structure of the clay. The
actual clay minerals are the hydrated
aluminum silicates, which may be
divided into three basic groups, the
kaolin group, the montmorillite group
and the illite group. Kaolin clays have a
non-expanding crystal structure, while
clays of the other two groups have
expanding crystal structures. Clays
with expanding crystal structures will
expand in volume when water is added,
and if this water evaporates, drastic
shrinkage and cracking will occur.
They are also very strong, with a high
heat resistance, and they show little
water damage even if they are shortly
wet after they have been made. Pure
kaolin is white and usually is found as
subsurface clay.
A mould may be nothing more
than four boards nailed together with
handles attached at either end. Our
first choice will be whether to have
a single or a multiple mould. Single
brick moulds appeals us because we
can tramp the soil down very firmly.
The sizes of the brick should be care-
fully considered in this research. The
sizes for the brick used in our case are
10cm×10cm×10cm.
Geogrids and woven geotextiles
have been used effectively to improve
the performance of embankment sand
back fills, by reducing deflections,
settlement, and earth pressures within
the embankments or backfills, and by
increasing the bearing capacity of these
structures.
This research tests compressive
strength of normal mud bricks and
shred geogrids reinforced mud bricks
with moisture content of 20% in pure
kaolin due to the compaction test on
kaolin with different water content in
geotechnical laboratory. The compac-
tion tests were performed by the stan-
dard proctor test, that the kaolin com-
pacted by 5.5lb hammer and the mold
was filled with three equal layers of
kaolin, where each layer is subjected to
25 drops of the hammer.
The materials of this research were
pure kaolin, shred geogrid and water.
The shred geogrids were same size,
since they were cut the same. Geogrids
are used only in soil reinforcement.
Geogrids represents a speed growing
segment within geosynthetics. Rather
than being a woven, nonwoven or knit-
ted textile fabric, geogrids are poly-
mers formed into a very open, grid like
configuration.
They have large apertures between
individual ribs in the machine and
cross machine directions. Geogrids are
(a) either stretched in one or two direc-
tions for improved physical properties,
(b) made on weaving or knitting ma-
chinery by standard textile manufac-
turing methods, or (c) by bonding rods
or straps together. There are many spe-
cific application areas; however, they
function almost exclusively as rein-
forcement materials.
Kaolin was used pure and without
addition materials. Kaolin is a clay
mineral with the chemical composition
Al
2
Si
2
O
5
(OH)
4
. It is a layered silicate
mineral, with one tetrahedral sheet
linked through oxygen atoms to one oc-
tahedral sheet of alumina. Kaolin-type
clays undergo a series of phase trans-
formations upon thermal treatment in
air at atmospheric pressure. Endother-
mic dihydroxylation (or alternatively,
Figure 1. Moulds in laboratory.
