pozzuolana

Century Dictionary and Cyclopedia

1. n. A material of volcanic origin, first found at Pozzuoli, near Naples, and afterward in many other localities, and of great importance in the manufacture of hydraulic cement. It is a volcanic ash, generally somewhat pulverulent, of various colors, and of different qualities in different localities. It closely resembles in origin and quality the so-called trass of Germany and the Netherlands. These substances consist chiefly of silicate of alumina with a small percentage of the alkalis, oxids of iron, etc. For making cement the pozzuolana is pulverized and mixed with lime and sand. The use of this material was well known to the Romans, and the preparation of hydraulic cement is described in detail by Vitruvius. Also pozzolana, puzzolana, puzzuolana, puzzolite, puzzolano.

Wiktionary

1. n. alternative spelling of pozzolana.

GNU Webster's 1913

1. n. Volcanic ashes from Pozzuoli, in Italy, used in the manufacture of a kind of mortar which hardens under water.