Finding and extracting raw materials

Earth for building should contain as little humus as possible. It must be firm with a good compressive strength and a low response to moisture. The most appropriate earth is found in moraine areas, as the grain size is suitable and the proportion of clay in the earth is within the limits of 10-50%. Clay can also be found in earth originally formed underwater - under the 'marine border', which varies according to geographical location but is usually around 220 m above sea level.

It is said that in Romania, where earth houses have been the most common form of building to the present day, even the children can classify the earths. Correct perception has become a tradition. The approximate clay content can be estimated through rolling out earth samples and judging their thickness, as shown in Table 8.6.

Table 8.6 Estimating the clay content of earth

Source: Lag, 1979.

Table 8.6 Estimating the clay content of earth

Source: Lag, 1979.

Thickness when rolled

Content of clay (%)

Cannot be rolled out

Less than 2

3-6 mm rolls

2-5

Approx 3 mm rolls

5-15

Approx 2 mm rolls

15-25

Approx 1-1.5 mm rolls

25-40

Approx 1 mm rolls

40-60

Rolls thinner than 1 mm

More than 60

Source: Lag, 1979.

Source: Lag, 1979.

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