Pozzolans are present on earth's surface such as
diatomaceous earth, volcanic ash, opaline shale, pumicite, and tuff. These materials require further
processing such as calcining, grinding, drying, etc.The Aegean
Mount Merapi Volcano erupting in Indonesia
Sarychev Volcano erupting on Matua Island (Kuril Islands.) Photo by International Space Station (6-12-09).
Tungurahua Volcano in
Popocatepetal Volcano in Mexico-volcanic ash.
Cascades Volcano Observatory (Courtesy
The City of Los Angeles Aqueduct (1910-1912)is comprised of portland cement and a natural pozzolan( a Rhyolite pumicite.) The Bonneville dam (1935) used portland natural pozzolan cement.
The piers of the San Francisco-Oakland Bay Bridge have natural pozzolan containing
Fly ash is an
artificial pozzolan produced when pulverized coal is
burned in electric power plants. The glassy (amorphous) spherical particulates
are the active pozzolanic portion of fly ash. Fly ash
is 66-68% glass. Class F fly ash (see ASTM C 618) readily reacts with lime
(produced when portland
cement hydrates) and alkalies to form cementitious compounds. Class C fly ash also may exhibit
hydraulic (self-cementing) properties. Hungry Horse, Canyon Ferry,
Power plant (Courtesy of Korean Electric Power Co. KEPCO)
Fly Ash (Courtesy of
A pozzolan requires
the presence of a reactive alumino silicate glass.
These glassy particulates must be fine enough to provide a sufficient reactive
surface area for the solid-state chemical reactions. This reactive glass reacts
with available calcium hydroxide and alkalies to
produce cementitious compounds calcium-silicate
hydrate gel and calcium-alumino silicates, etc.)
Bear River Zeolite in Preston, Idaho
Lassenite SR Pozzolan (Northern California, See Western Pozzolan
Lava S.A Pozzolanic Rock Milos Greece see LAVA
Pagan Island Pozzolan Northern Mariana Islands see here.