>Pumice Defined

 Uses for Pumice

 Worldwide Application

 Hybrid Applications

 Affordable Housing








Pumice-Crete® is a low density concrete made from pumice aggregate, portland cement, and water. It is a mix that succeeds in providing structural strength and insulation in one material. Typically it is poured on site in wall thickness of 14" or greater and no additional insulation or structural components are necessary. Wall surfaces are finished by applying plaster coats on the interior and exterior which further aid the thermal performance by trapping air within the honeycomb Pumice-Crete® mix. The walls are very durable, fireproof, have good noise resistance, and are very aesthetically pleasing because they can be formed to fit many architectural appearances and styles. Being lightweight Pumice-Crete® is relatively easy to install and is cast on site out of not highly manufactured ingredients making it a very resource efficient material. Pumice-Crete® buildings are warm and easy to heat in the cold of winter and stay cool and comfortable in the heat of summer. Pumice is a lightweight volcanic rock that is found in many parts of the world where volcanoes are present. It is a sponge like material formed by expansion of gases while molten lava rapidly cooled. It is a porous glass froth that is found in very shallow deposits in such places as New Mexico, Arizona, California, Oregon, Washington, and Idaho. Due to its toughness and durability it has been used as a lightweight aggregate in concrete for over two thousand years. It is an inert material and therefore has no reaction with any of the ingredients of concrete and steel. Its loose weight, in damp condition, is from 950 to 1300 lbs. per cubic yard, depending on the grading of the material.

Pumice aggregate is mixed with only enough cement and water to produce a light concrete with a cured strength of 400 PSI. Only enough cement is used to coat the aggregate and bind it together where it touches. This is a lean mix and no attempt is made to fill the space between the stones. This makes for a honeycomb like material with an evenly coarse surface. For most one and two story applications this is adequate structurally and self supporting with no need for additional support members. More cement increases the strength but reduces the thermal insulating quality whereas less cement increases the thermal insulating qualities but reduces the structural adequacy

Our basic mix for exterior walls on a single story structure uses under 3 sacks of portland cement for every cubic yard of aggregate with water being the only other ingredient. This material reaches 400 PSI strength quickly and has a thermal insulating value that I estimate to be R-I.5 or more per inch. It is no where near the structural strength of typical concrete used today which are usually 2000 PSI and above but those strengths are not necessary in thick wall situations.

Low Density Concretes are those that have a cured weight of over 20 pounds per cubic foot and under 50 pounds per cubic foot. The Pumice-Crete® mix most commonly used weighs just under 50 pounds per cubic foot once cured which puts it at the heavy end of the low density concrete spectrum. A yard of Pumice-Crete® weighs around 1250 to 1350 pounds. This is an average weight and can be 10% more or less depending on actual mix design.

PO Box 539, EL Prado, New Mexico 87529



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