Field Testing of Brick Earth

Brick earth in the field has to be tested for consistency, moulding properties and shrinkage.

In order to test for the first property, a handful of soil sample is taken and formed into a ball. The ball is dried in the sun and then examined. Crumbling of the dried ball shows the presence of excess sand. If the ball is hard and shows cracks on the surface, it indicates the presence of less sand. Thus, the soil has to be modified by mixing different proportions of sand or clay such that the above-mentioned defects do not occur.

The soil found or made suitable in the first test is taken and ground well. Then a required quantity of water is added and mixed. The mixed soil is kneaded well to be rolled to form threads of about 3 mm diameter without crumbling. Such a mixture of soil and water is used to make a brick using a mould. The moulded brick should be with clear edges and corners which ensures perfect requirement of water. Otherwise water is added or removed to get a satisfactory brick.

Sample of bricks moulded as above are burnt in a clamp until bricks become red hot. These bricks are examined for shrinkage and deformation after cooling. Bricks which have shrunk evenly and do not show any defects are separated out and others are rejected. The percentage of sorted out bricks should be high, otherwise the soil is modified to get a better percentage of good bricks.