3. How were they able to make it?
In their spare time, the Romans managed to invent
cement, a mixture of lime, clay, and water. They
constructed the rounded arch, commonly called the
Roman arch, and perfected it into various forms.
The Roman arch contains "voussoirs”, or bricks.
The "keystone" is the center voussoir that supports
the other bricks. The push or thrust of the cemented
voussoirs push outward and downward in the arch.
A row of arches is called an "arcade.”
5. Construction
An arch requires all of its elements to hold it together, raising
the question of how an arch is constructed. One answer is to
build a frame (historically, of wood) which exactly follows the
form of the underside of the arch. This is known as a centre or
centring. The voussoirs are laid on it until the arch is complete
and self-supporting. For an arch higher than head height,
scaffolding would in any case be required by the builders, so the
scaffolding can be combined with the arch support.
Occasionally arches would fall down when the frame was
removed if construction or planning had been incorrect. (The
A85 bridge at Dalmally, Scotland suffered this fate on its first
attempt, in the 1940s). The interior and lower line or curve of an
arch is known as the intrados.
Old arches sometimes need reinforcement due to decay of the
keystones, known as bald arch.
6. The Romans used the arch shape in most of their public
buildings. Triumphant arches were built to honor the
great achievements of emperors and generals in Rome.
Some of the arches included:
Arch of Titus
Arches of Constantine
Arch of Septimus Severus
Arch of Trajan
9. How does it connect to our society?
We have buildings with arches in
America.
We use them for designs on buildings.
Our bridges are examples of modern
arches.
