Concrete Waterproofing Glossary
Vacuum Concrete
concrete from which excess water and entrapped air are extracted by a vacuum process before setting occurs.
Vacuum Saturation
a process for increasing the moisture content of lightweight aggregate by subjecting it to a vacuum in a sealed chamber, flooding the chamber with water, and releasing the vacuum.
Valve Bag
paper bag for cement or other material, either glued or sewn, made of four or five plies of kraft paper and completely closed except for a self-sealing paper valve through which the contents are introduced and released.
Vapor Barrier
membrane located under a concrete floor slab that is placed on the groundto retard transmission of water vapor.
Vapor Pressure
the pressure exerted when a vapor is in equilibrium with its liquid or solid form at a given temperature.
Vapor Retarder
a membrane that impedes the transmission of gas molecules.
Vebe Apparatus
an apparatus for measuring workability of very low-slump or no-slumpconcrete, including a vibrating table, a sample container, and other ancillary items, that permits measurement of the time (vebe time) required to be consolidated in a mold.
Vehicle
liquid carrier or binder of solids.
Veneer
a masonry facing that is attached to the backup, but not so bonded as to act with it under load.
Vertical-shaft Mixer
a cylindrical or annular mixing compartment having an essentially level floor and containing one or more vertical rotating shafts to which blades or paddles are attached; the mixing compartment may be stationary or rotate about a vertical axis.
Vibrated Concrete
concrete consolidated by vibration during and after placing.
Vibration
energetic agitation of freshly mixed concrete during placement by mechanical devices, either pneumatic or electric, that create vibratory impulses of moderately high frequency to assist in consolidating the concrete in the form or mold.
(1) external vibra
Vibration Limit
the age at which fresh concrete has undergone a sufficient degree of setting and developed adequate strength to resist flow when subjected to vibration.
Vibrator
an oscillating machine used to agitate fresh concrete so as to eliminate gross voids, including entrapped air but not entrained air, and to produce intimate contact with form surfaces and embedded materials. (See also vibration.)
Vicat Apparatus
a penetration device used in the testing of hydraulic cements and similar materials.
Vicat Needle
a weighted needle for determining time of setting of hydraulic cements.
Viscometer
instrument for determining viscosity of slurries, mortars, or concretes.
Viscosity
a measure of the resistance of a fluid to deform under shear stress.
Void-cement Ratio
volumetric ratio of air plus net mixing water to cement in a concrete or mortar mixture.
Volatile Material
material that is subject to release as a gas or vapor; liquid that evaporates readily.
Volume Batching
combining the constituents of mortar or concrete based on volumetric measurement. (See also volumetric measuring.)
Volume Change
an increase or decrease in volume due to any cause. (See alsodeformation and time-dependent deformation.)
Volumetric Measuring
dispensing an ingredient based on volume, either in discrete quantities orby continuous flow.
Volumetric Mixer
equipment that uses measurements based on the volumes of the ingredients to feed a container that continually agitates and combines those ingredients for the production of concrete (also called volumetric- measuring and continuous-mixing concrete equipmen