Concrete made of Portland cement, mixed with sand, crushed stone, pieces of burnt fire clay, broken bricks or tiles, has been successfully used in Europe as a fireproof material for many years, and what few tests have been made upon it appear to prove that it is a highly fire-resisting material, and it is now so considered by well-informed engineers and architects.
Professor Bauschinger, of the Munich Technical School, tested pillars of various materials by repeatedly heating them red hot and then drenching them with water. In his report he says: "Of all materials tested Portland cement concrete stood the best, and ordinary and clinker brick laid in Portland cement mortar stood almost equally as well."
. Concrete construction has been largely used in California for many years on account of its fireproof qualities, and it is probable that it will be much more extensively used in the future in all portions of the country.
Plaster Concretes. - In Paris a composition of plaster of Paris and broken brick, chips, etc., has been used for generations for f6rming ceilings between beams, and its durability is there unquestioned. A composition consisting of 5 parts by weight of plaster of Paris and 1 part of wood shavings, mixed with sufficient water to bring the mass to the consistency of a thin paste, has been lately introduced in this country in connection with the Metropolitan system of floor construction. It is claimed that this material is so remarkable a nonconductor of heat that a moderate thickness of it prevents the passage of nearly all warmth.
"In severe fire tests the beams have remained cold, and consequently were unaffected. When exposed to flame for a long time the composition is attacked to a depth of from 3/16 to 5/8 of an inch, the remainder being unaffected, and when water is thrown upon it the mass does not fly or crack. When made thoroughly wet the composition is not destroyed."
This composition is much lighter in weight than ordinary cement concrete.
Lime mortar, and most, if not all, of the hard mortars or patent plasters, when applied on metal lathing, will resist almost any degree of heat, and will withstand the action of water for a long time.