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Concrete Repair Terminology (U-V)
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Concrete Repair Terminology is prepared by the International Concrete Repair Institute. The cross-referenced terms provide definitions for commonly used words in concrete repair, restoration and protection.

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Revised April 2019

A   |   B   |   C   |   D   |   E   |   F   |   G   |   H   |   I   |   J-L   |   M   |   N-O   |   P   |   Q-R   |   S   |   T   |   U-V   |   W   |   X-Y-Z

- U -


pertaining to mechanical vibrations having a frequency greater than approximately 20,000 Hz.

ultrasonic echo

a nondestructive testing method for locating delaminations and voids in relatively thin elements with a transducer that emits a short pulse of ultrasonic waves which is reflected by the opposite side of an element or internal defect and recorded by an adjacent receiver.

ultrasonic pulse velocity

a nondestructive testing method for assessing the relative condition of hardened concrete by measuring the travel time of a pulse of ultrasonic waves through a section with a known path length.

uniform corrosion

corrosion that occurs at approximately the same rate over a metal surface; sometimes referred to as general corrosion.


a structure or individual structural member that is dangerous or that constitutes a fire hazard.


the interception, removal, or control of ponded or flowing surface water within structures or excavations. (See also dewatering.)


to improve the quality, effectiveness, or performance of a structure or its structural or nonstructural components (for example, the seismic upgrade of a building by increasing the strength or deformation capacity of columns).


vertical displacement of a structure or formation because of grout injection.


white crystals or powder, soluble in water and used as a deicer.

urea resin



not firmly made, placed, or fixed; subject to deterioration or disintegration during service exposure.

- V -

vacuum blasting

a closed-loop abrasive blasting process whereby blasting material and associated debris are contained with a vacuum. (See also shotblasting.)

vacuum concrete

vacuum impregnation

a repair process in which a vacuum applied to a concrete section causes polymers such as epoxy to impregnate the concrete surface or fill cracks and voids within the section.

vapor barrier

a moisture impervious layer that eliminates transmission of water vapor into a material or structure.

vapor retarder

a material that minimizes transmission of water vapor but is not 100% effective in preventing its passage.


the liquid portion of coating in which pigment is dispersed; composed of binder and thinner.


a hole or small-diameter pipe used in concrete construction to permit escape of air in a structure being concreted or grouted; also used to monitor the flow of grout.


1) energetic agitation of freshly mixed concrete during placement by internal or external 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; 2) movement induced into a structure by the impact from mechanical concrete removal tools that may result in damage to the existing structure.

vibration modal analysis

the breaking down of a set of vibrations in a structure or component into independent frequencies and amplitudes.


an oscillating machine used to agitate freshly-mixed materials such as concrete or mortar to produce a uniform material without gross voids, and to produce intimate contact with the substrate, boundary of repair cavity, form surfaces, and embedded materials.

vinyl ester resin


instrument used for measuring viscosity of slurries, mortars, or concretes.


the property of a material that resists change in the shape or arrangement of its elements during flow, and the measure thereof.

viscosity modifier

visual inspection

an evaluation procedure in which a qualified investigator observes, classifies, and documents deterioration or distress on exposed concrete surfaces; typically, one of the first steps in evaluation of a concrete structure.


cavity enclosed within an otherwise solid mass; may be intentionally or unintentionally formed and may be filled with air, water, or other gaseous or liquid material.

void ratio

the ratio of the volume of void space to the volume of solids.

volatile content

the percentage of materials which evaporate from a coating.

volatile organic compounds (VOC)

a measure of the total amount of organic compounds evaporating from a coating film, excluding water.

volume change

an increase or decrease in volume of a material. (See also deformation and deformation, time-dependent.)

volume change, autogenous

change in volume produced by continued hydration of cement, exclusive of effects of applied load and change in either thermal condition or moisture content.

volume change, thermal

the increase or decrease in volume caused by changes in temperature. (See also thermal contraction and thermal expansion.)

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