Utilization of cow-dung in brickmaking
Practical Action
The far south and southwest have leached lateritic soils. Central Sudan, known as "clay plain",
consists of alkaline soils containing the clay mineral montrnorillonite. The northern clay plain
soils are generally weathered sediments derived from the volcanic Ethiopian highlands. These
soils are commonly alkaline, containing calcium carbonate and gypsum, with the clay fraction
composed largely of montmorillonite.
The southern plain soils are thought to be residual soils and are similar to the northern plain
soils but without gypsum. In addition, as already noted, alluvial soil occur along the Nile and
portions of other rivers.
Aspect of comparison
Before 1949 1949 -1956
After 1956
Length, cm
22.2 - 23.5 21.3 - 21.6 18.6 - 19.7
Width, cm
Depth, cm
Water absorption, %
10.6 - 11.2
5.5 1- 15..28
23.7 - 351.8.1
10.4 – 10.5
6.5 - 160.6.5
19.0 - 226..06
9.0 - 9.8
4.3 - 5.5
28.3 - 38.1
Strength, kg/ cm2
29.1 -116.8 60.0 - 120.0 21.5 - 58.0
Table (1): Fluctuation of dimensions in bricks and properties with time
The distribution of soils as outlined above is not clear cut. Soils vary over very short distances as
shown in Table (2). Balabata, Zafota and Gurera are local names of soils. The same soils may
have other names in different parts of Sudan. Depending on the sand content some of the soils
are brittle when formed into bricks unless reasonable portions of organic components are added.
Different layers are mixed by cutting vertically when winning clay for making bricks. Cow-dung
reduces brittleness and improves workability.
Agricultural and Other Residues
High cost of energy for brickmaking and in other sectors, including households, motivated many
institutions to conduct research aimed at exploring the use of waste and residues as alternative
fuel to wood. Sudan has huge agricultural wastes and other residues estimated by NEA(5) to be
10 million metric tonnes per year (1993). The most important and promising of these are stalks
of various crops such as sorghum, cotton, sunflower, and shells or husks of maize, groundnuts
and coffee. Some seeds like "garad"(6) can also be incorporated into clays. Agricultural wastes
can be used as solid fuels for firing kiln tunnels. However, because of their low unit weight, they
have to be processed by way of compaction to reduce transport costs. Some attempts to gasify
some plants e.g. hyacinth and agglomerate charcoal fines were technically quite successful, yet
more efforts are needed to make the end-products commercially viable.
Component
Composition by
Bwaeilgahbtata
Zafota
Gurera(4)
SiO2
Ai2O3
Fe203
TiO2
CaO
44.21
17.03
11.11
2.53
5.57
49.09
15.68
10.07
1.85
6.32
75.04
8.23
4.35
0.90
4.67
MgO
3.01
2.52
1.07
K2O
Na2O
1.75
0.95
2.53
2.10
1.26
0.73
L.O.I
12.82
8.08
5.58
Table (2): Chemical composition of Balabaty. Zafota and Gurera Clays at Geriefshark, Khartoum.
It has been found out that dung is another form of waste which can be utilized in building, as
well as in agriculture. Cowdung is mixed with brick clays, goat dung used as a fertilizer and
donkey dung as a protective coating of mud walls and roofs.
2