Pozzolana

Pozzolana or pozzuolana (/ˌpɒts(w)əˈlɑːnə/ POT-s(w)ə-LAH-nə, Italian: [potts(w)oˈlaːna]), also known as pozzolanic ash (Latin: pulvis puteolanus), is a natural siliceous or siliceous-aluminous material which reacts with calcium hydroxide in the presence of water at room temperature (cf.

Vitruvius speaks of four types of pozzolana: black, white, grey, and red, all of which can be found in the volcanic areas of Italy, such as Naples.

[1] The easily alterable, or highly reactive, nature of these ashes and pumices limits their occurrence largely to recently active volcanic areas.

Most of the traditionally used natural pozzolans belong to this group, i.e., volcanic pumice from Pozzuoli, Santorin earth and the incoherent parts of German trass.

Quartz is usually present in minor quantities in acidic pozzolanas, while pyroxenes and/or olivine phenocrysts are often found in more basic materials.

Pozzolana is abundant in certain locations and is extensively used as an addition to Portland cement in countries such as Italy, Germany, Kenya, Uganda,Turkey, China and Greece.

The application of pozzolana in Portland cement is mainly controlled by the local availability of suitable deposits and the competition with the accessible industrial by-product supplementary cementitious materials.