The History of Building Construction (Bronze Age)
It was the cultures of the great river valleys—including the
Nile, the Tigris and Euphrates, the Indus, and the Huang Ho—with their
intensive agriculture based on irrigation—that developed the first communities
large enough to be called cities. These cities were built with a new building
technology, based on the clay available on the riverbanks. The packed clay
walls of earlier times were replaced by those constructed of prefabricated
units: mud bricks. This represented a major conceptual change from the free
forms of packed clay to the geometric modulation imposed by the rectangular
brick, and the building plans too became strictly rectangular.
Bricks were made from mud and straw formed in a four-sided
wooden frame, which was removed after evaporation had sufficiently hardened the
contents. The bricks were then thoroughly dried in the sun. The straw acted as
reinforcing to hold the brick together when the inevitable shrinkage cracks
appeared during the drying process. The bricks were laid in walls with wet mud
mortar or sometimes bitumen to join them together; openings were apparently
supported by wooden lintels. In the warm, dry climates of the river valleys,
weathering action was not a major problem, and the mud bricks were left exposed
or covered with a layer of mud plaster. The roofs of these early urban
buildings have disappeared, but it seems likely that they were supported by
timber beams and were mostly flat, since there is little rainfall in these
areas. Such mud brick or adobe construction is still widely used in the Middle
East, Africa, Asia, and Latin America.
Later, about 3000 BC in Mesopotamia, the first fired bricks
appeared. Ceramic pottery had been developing in these cultures for some time,
and the techniques of kiln-firing were applied to bricks, which were made of
the same clay. Because of their cost in labor and fuel, fired bricks were used
at first only in areas of greater wear, such as pavements or the tops of walls
subject to weathering. They were used not only in buildings but also to build
sewers to drain waste water from cities. It is in the roofs of these underground
drains that the first surviving true arches in brick are found, a humble
beginning for what would become a major structural form. Corbel vaults and
domes made of limestone rubble appeared at about the same time in Mesopotamian
tombs. Corbel vaults are constructed of rows of masonry placed so
that each row projects slightly beyond the one below, the two opposite walls
thus meeting at the top. The arch and the vault may have been used in the roofs
and floors of other buildings, but no examples have survived from this period.
The well-developed masonry technology of Mesopotamia was used to build large
structures of great masses of brick, such as the temple at Tepe Gawra and the
ziggurats at Ur and Borsippa (Birs Nimrud), which were up to 26 meters (87
feet) high. These symbolic buildings marked the beginnings of architecture in
this culture.
The development of bronze, and later iron, technology in
this period led to the making of metal tools for working wood, such as axes and
saws. Less effort was thus required to fell and work large trees. This led in
turn to new developments in building Technics; timbers were cut and shaped extensively,
hewed into square posts, sawed into planks, and split into shingles. Log cabin
construction appeared in the forested areas of Europe, and timber framing
became more sophisticated. Although the excavated remains are fragmentary,
undoubtedly major advances were made in timber technology in this period; some
of the products, such as the sawed plank and the shingle, are still used today.
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