Harmful Ingredients in Brick Earth

Naturally available soil may contain ingredients other than those required for making quality bricks, which are discussed below.

1. Alkalis

Alkalis in the form of soda and potash lower the fusion point of clay, and cause bricks to fuse, twist and warp during burning. Alkalis present in bricks absorb moisture from the atmosphere and create dampness. Such dampness dries and leaves behind grey or white deposits on the surface of the wall.

2. Pebbles

Although the presence of pebbles causes harm chemically, they are not desirable as they do not permit the clay to be thoroughly mixed uniformly resulting in weak and porous bricks. Regular breaking of bricks during masonry work is not possible because of the presence of pebbles.

3. Iron Pyrites

The presence of iron pyrites in brick earth causes the earth to decompose and oxidize resulting in the splitting of bricks.

4. Vegetation and Organic Matter

Vegetation and organic matter when present in brick earth assists in burning. Incomplete burning of these materials causes the bricks to become porous.

5. Limestone

Limestone and kankar nodules present in brick earth are harmful as that of lumps of lime. On heating limestone is converted into lime, which comes into contact with water, swells and finally results in splitting and crumbling.