pozzolana
/ˌpɒtsəˈlɑːnə
/noun [mass noun]
A type of volcanic ash used for mortar or for cement that sets under water.The ashes have been potential pozzolanic materials suitable for use in lime - pozzolana mixes and for Portland cements replacement....
- It included seawater, lime and sand (pozzolana) and chunks of volcanic rock from the Bay of Naples - the same source for material used in ancient construction efforts at Caesarea and elsewhere in the region.
- The Romans invented concrete, mixed from pozzolana, a volcanic ash mined on the slopes of Mount Vesuvius, which forms a natural cement when combined with lime.
Origin
Early 18th century: from Italian, from pozz(u)olana '(earth) of Pozzuoli', a town near Naples.