While quarrying limestone on the slopes of
Mt. Vesuvius, ancient Roman engineers
stumbled upon a naturally occurring cement
created by the extreme temperatures and
pressures of the volcano. They discovered
that the silica-alumina substance, when
mixed with limestone and burned, would
harden underwater as well as in the air,
unlike mortar. They also found that the
material was much harder and stronger than
ordinary lime mortar.
This material, which contained the essential
elements of today's man-made portland
cement, changed the character of Roman
construction. Initially, columns, arches and
vaults were built with masonry facings, then
filled internally with the Vesuvian cement.
Later, the plasticity and moldability of wet
cement was exploited for the construction of
new architectural forms: Roman