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close this bookJournal of the Network of African Countries on Local Building Materials and Technologies - Volume 2, Number 4 (HABITAT, 1993, 66 p.)
close this folderTechnology profiles:
View the document1. Manufacture of bricks by a semi-mechanized process including high-draught kiln*
View the document2. Manufacture of bricks from alumina red mud*
View the document3. Manufacture of bricks from red murrum soil*

3. Manufacture of bricks from red murrum soil*

* Developed by the Central Building Research Institute (CBRI), Roorkee, India.

Red murrum soils present difficulties in producing good quality bricks due to their coarse, highly siliceous and non-plastic nature, short vitrification range and lime-bursting.

Generally, bricks produced out of red murrum soils are porous and of low strength (20-25 kg/cm2).

The Central Building Research Institute (CBRI) has been studying the murrum soil of Hyderabad for some time and has developed processes for making bricks of a compressive strength in the range of 100 kg/cm2 from it.

Processing of red murrum soil for brick manufacture

According to the methods worked out in CBRI, bricks of improved quality can be produced from red murrum soil processed by any of the following four alternative methods:

(a) An admixture of 70-per cent red murrum soil and 30-per cent clayey soil, wherever it is available around low-lying areas, tank beds, banks of rivers, etc., is used for moulding bricks. For the purpose of calcination, it is assumed that clayey soil would be transported an average distance of five miles. Calcination would be undertaken to remove oversize particles above 1-2 mm, and the refuse material after the calcination treatment would be disposed off.

(b) The process is the same as in (a) above, except that, clayey soil is assumed to be available in close vicinity of the moulding site.

(c) Red soil is used without any admixture of clayey soil. The calcination method is followed to remove oversize material above 1 mm and the refuse material is disposed off.

(d) Red soil, as a whole, is used. The calcination method is not applied, but instead red soil is ground to 1-mm size in a pan-mill before it is used for brick-moulding.

Calcination method

The calcination method of separating lime nodules and coarse particles present in the soil is widely practised in Madhya Pradesh and Maharashtra. In this process the raw soil is dispersed with excess water in calcination tanks. The clay is worked manually to ensure complete disintegration.


Figure 1. Process flow chart for the manufacture of bricks from red murrum soil

A: Clayey soil is transported from a distance of five miles
B: Clayey soil is available close to moulding site
C: With calcination process but without clayey soil
D: Red soil as a whole without calcination process

* Developed by the Central Building Research Institute (CBRI), Roorkee, India.

The lime nodules and coarse particles are then scooped out of the dispersion using baskets with holes in them. The suspension is thereafter drawn out of the tank into a settling tank through a sieve to separate any nodules left behind. When the clay settles down, the supernatant water is syphoned off. The clay is then allowed to dry to a plastic consistency It is then ready for moulding bricks. It is envisaged that this process would be carried out manually.

Firing the bricks

It is important that the firing of bricks is done in a temperature range of 780-830°C Hence, the adoption of Bull's trench kiln is recommended instead of clamps Bull's kilns are known for continuous operation and they turn out a higher percentage of first quality bricks

Scheme for the production of improved bricks

From red murrum soil

(a) The manufacturing process is shown in a flow chart (see figure 1)

(b) Production scale

(i) Rate of production

25,000 brick per day (3 shifts)

7.5 million bricks per year of 300 working days

(ii) Details of bricks

Size 22.5 × 11.25 × 7.5 cm


Raw materials*




1.

Clay

18,750 m3

2.

Water

3 750 m3

* For one year's production and production methods (a), (b) and (c)


Utilities




1.

Electric power

108,000 kWh

2.

Coal

1 600 t

3.

Wood

20 t

4.

Consumable:
moulds, sand, chimney, oil, grease etc.




Workforce








(a)

(b)

(c)

1.

Operator for disintegrator

-

-

-

2.

Labour

60

60

55

Energy consumption for day's production


Machinery/equipment

Energy



Electrical

Thermal




Coal

Wood

1.

Disintegrator for production process (c)

360 kWh

-

-

2.

Lighting, fans, water supply etc. for all production processes

125 kWh

-

-

3.

Kiln (in all production processes)

-

5300 kg

70 kg