Bricks—Ancient Building Blocks at Modern Man’s Service
BY “AWAKE!” CORRESPONDENT IN PORTUGAL
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? (Ex. 5:6-18) 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.”—Gen. 11:3, 4.
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.
A more modern system is called the continuous-car tunnel system. In this method, as soon as the raw bricks are cut to size, they are stacked on flatcars, slowly passed through long, heated tunnels and after from 8 to 72 hours (depending on the type of brick) they are dry. Now they are moved slowly through a long fire-brick tunnel, where they are heated and cooled in from 36 hours to four days, also depending on the type of brick. One of Portugal’s largest brick factories, located outside Lisbon, has a modern continuous-car tunnel oven 180 m (590 feet) long!
Standardization
When bricks were manufactured manually, their form and dimensions varied widely from region to region, adapting themselves to the local necessities. However, even the Assyrians recognized the need to standardize the dimensions of the most widely used bricks of their time.
In Portugal, the National Civil Engineering Laboratory made an inquiry of the principal factories as to the forms and dimensions of bricks produced. The 44 factories that answered the inquiry produced 330 different models!
This great diversity caused many inconveniences, for manufacturer and consumer alike. As bricks occupy a very important role in construction here in Portugal, standardization would be very beneficial, not only as to quality, but also as to dimensions and materials. With the results of this inquiry at hand, it was now necessary to determine how to limit the existing types. Ninety-nine different factories and 36 of the larger consumers collaborated in this study.
The results of the study were presented in a seminar on productivity in the ceramic industry. Reasons for the proposal were given, and the discussion was opened to questions and observations to detect any other unknown factors that could alter the proposal. Final conclusions were reached and presented to the participants, together with reasons for the decisions.
In the following year, a final document was published and approved, reducing the number of different types of bricks to seven. The document was widely published, and manufacturers and builders alike recognized the advantages of it. Thus, they began to limit their activities to the new standards. Then the document was published officially as a standard for all of Portugal. While the changeover took time, today it enjoys almost total adherence.
The brick, an ancient building block, continues to enjoy very wide use in spite of the advances made in metallic and reinforced concrete construction. If your home is not built of brick, maybe the chimney is, or perhaps the fireplace, or the barbecue area in your backyard. Here in Portugal, as in many other countries around the world, the brick continues humbly to serve modern man because of its time-proven qualities.