Bricks: Ancient Building Blocks at Modern Man's Service

What is your house built of? Wood? Stone? Or perhaps straw?

Here in Portugal practically all homes use bricks as a basic building material. Approximately 600 brick factories throughout the country produce more than two hundred million units annually. But such use of bricks is not new.

From Early Times

Did you know that bricks were employed in ancient world empires, such as Assyria, Babylon and Egypt? When post-Flood city building was first begun, the humble brick was there.

In the third millennium before our common era, builders in the land of Shinar determined to construct a city with a monument huge enough to leave their mark on history. And they began to say, each one to the other: 'Come on! Let us make bricks and bake them with a burning process.' So brick served as stone for them, but bitumen served as mortar for them.

Excavations in Ur of Chaldea reveal that bricks were used extensively in Mesopotamia for construction, due to the lack of stone or forested areas. The rich alluvial plain built up by silt from the flooding Euphrates and Tigris Rivers provided the natural material needed.

If you had lived in Babylon in the days of Nebuchadnezzar, you would be very familiar with the brick walls flanking both sides of the main boulevard, Procession Street. This street displayed a long row of snarling lions, all rendered in molded, strongly colored enamel bricks. At the end of Procession Street was Ishtar Gate, next to the brick palace of Nebuchadnezzar, and on the gate were reliefs of bulls sculptured in glazed brick.

Manufacture

In ancient times, brickmaking was a very simple process. Mud clay was placed in handmade wooden molds and left in the sun to dry. Straw was often mixed in with the clay to give added strength. Such sun-dried bricks are today called adobe, and are still used in some countries with dry climates. In time, another process was added, that of kiln-drying (oven-drying), giving more durability to the brick.

The modern production of bricks involves the following basic steps. Raw or burned clay and water are mixed, with other mineral matter such as sand, limestone, dolomite and substances containing compounds of iron and other metals being added. The soft-mud process involves the molding of each brick individually to shape and size. In the modern stiff-mud process, the clay mixture is molded into shape as it is extruded under pressure through a die to form a continuous column of clay, and is then cut by wires to the desired brick length. Our bricks are now ready for two final processes: drying and firing.

The first, the drying process, may be done by natural means or artificially. The second, the firing, or baking, requires the use of large kilns or ovens. Here in Portugal, smaller operations may use the intermittent "beehive" kiln. Bricks are stacked inside by hand, then fired and cooled intermittently during five to seven days. Many larger factories use the Hoffman-type kiln, a long, narrow oven, inside of which are stacked the bricks, and the firing system moves progressively from one end to the other.