Impermeable |
(Concrete Engineering) The ability of a material or product to reduce or eliminate gaseous transmissions through it's mass; measured as the rate of Water Vapor Transmission (WVT). Note: Not all materials that are waterproof are vaporproof; all materials that are vaporproof are inherently waterproof. |
Jacking Force |
(Concrete Engineering) The temporary force exerted by the jacking device which introduces tension into the tendons. Jacking Stress In prestress concrete, the maximum stress occurring in a tendon during stressing. |
Keene's Cement |
(Concrete Engineering) A finely ground high density plaster composed of anhydrous, (calcined or "dead burned") gypsum, the set of which is accelerated by the addition of other materials. |
Magnetite |
(Concrete Engineering) An aggregate used in heavy weight concrete, consisting primarily of ferrous metaferrite (Fe304). A black magnetic iron ore with a specific gravity of approximately 5.2 and a Mohs hardness of about 6. |
Maximum Size Aggregate |
(Concrete Engineering) Aggregate whose largest particle size is present in sufficient quantity to affect the physical properties of concrete; generally designated by the sieve size on which the maximum amount permitted to be retained is 5 or 10 percent by weight. |
Mixing Speed |
(Concrete Engineering) Rate of mixer drum rotation or that of the paddles in a pan, open-top, or trough type mixer, when mixing a batch; expressed in revolutions per minute (rpm) or in peripheral] feet per minute of A point on the circumference at maximum diameter. |
Neat Cement-Paste |
(Concrete Engineering) A mixture of water and hydraulic cement, both before and after setting and hardening. |
Non-agitating Unit |
(Concrete Engineering) A truck-mounted unit for transporting ready-mixed concrete short distances, not equipped to provide agitation (slow mixing) during delivery. |
Non-evaporable Water |
(Concrete Engineering) The water in concrete which is irremovable by oven drying; chemically combined during cement hydration. |
Ottawa Sand |
(Concrete Engineering) A sand used as a standard in testing hydraulic cements by means of mortar test specimens. Sand is produced by processing silica rock particles obtained by hydraulic mining of the orthoquartzite situated in open-pit deposits near Ottawa, Illinois; naturally rounded grains of nearly pure quartz. |