galvanic corrosion—accelerated corrosion of a metal because of an electrical contact with a more noble metal or a more noble nonmetallic conductor in a corrosive electrolyte.
ganged forms—see forms, ganged.
ganister—a highly refractory siliceous sedimentary rock used for furnace linings.
gap-graded aggregate—see aggregate, gap-graded.
gap-graded concrete—see concrete, gap-graded.
gas concrete—see concrete, gas.
gauge water—see batched water (preferred term).
gehlenite—a mineral of the melilite group, Ca2Al(AlSi)O7. (See also akermanite; melilite; merwinite.)
gel—(1) matter in a colloidal state that does not dissolve, but remains suspended in a solvent from which it fails to precipitate without the intervention of heat or of an electrolyte. (2) the condition where a liquid grout begins to exhibit measurable shear strength.
gel, cement— the colloidal material that makes up the major portion of the porous mass of which mature hydrated cement paste is composed.
gel, tobermorite—the binder of concrete cured moist or in atmospheric-pressure steam; a lime-rich gel-like solid containing 1.5 to 1.0 mols of lime per mol of silica.
gel time—the time interval between mixing the constituents of a liquid material and the formation of a gel.
geomembrane—a flexible, watertight polymeric membrane with a thickness of one-half to a few millimeters; a wide range of polymers, including plastics, elastomers and blends of polymers are used to manufacture geomembranes.
geonet—a geosynthetic consisting of integrally connected parallel sets of ribs overlying similar sets at various angles for planar drainage of liquids and gases.
Gillmore needle—see needle, Gillmore.
girder—a large beam, usually horizontal, that serves as a main structural member.
girt—small beam spanning between columns, generally used in industrial buildings to support outside walls. (See also beam.)
glass—an inorganic product of fusion that has cooled too a rigid condition without crystallizing, sometimes reactive with alkalies in concrete.
glass fibers—see fibers, glass.
glass-fiber reinforced cement—a composite material consisting essentially of a matrix of hydraulic cement paste or mortar reinforced with glass fibers; typically precast into units less than 1-in. (25-mm) thick.
glass-transition temperature—see temperature, glass-transition.
global stability––the stability of the overall structure with respect to uplift, overturning, sway instability or sliding failure; global stability failures result in the collapse of a structure.
go-devil—a ball of rolled-up burlap or paper or a specially fabricated device put into the pump end of a pipeline or tremie pipe immediately prior to introduction of the concrete and forced through the pipe to keep the concrete from mixing with water in the pipe as the concrete flows to the bottom of the pipe; also used to clean pipelines and tremie pipes.
grab set—see set, flash (preferred term).
gradation—see grading (preferred term).
grade—the prepared surface on which a concrete slab is cast; the process of preparing a plane surface of granular material or soil on which to cast a concrete slab.
grade beam—see beam, grade.
grade strip—see strip, grade.
graded standard sand—see sand, standard.
gradient—rate of change in a variable over a distance, as of temperature or moisture.
grading—the distribution of particles of granular material among various sizes; usually expressed in terms of cumulative percentages larger or smaller than each of a series of sizes (sieve openings) or the percentages between certain ranges of sizes (sieve openings).
grading, combined-aggregate—particle-size distribution of a mixture of fine and coarse aggregate.
grading, continuous—a particle size distribution in which intermediate size fractions are present, as opposed to gap-grading. (See also aggregate, gap-graded.)
grading curve—see curve, grading.
granolithic concrete—see concrete, granolithic.
granolithic finish—see finish, granolithic.
granulated blast-furnace slag—See blast-furnace slag.
gravel—(1) granular material predominantly retained on the 4.75 mm (No. 4) sieve and resulting either from natural disintegration and abrasion of rock or processing of weakly bound conglomerate; and (2) that portion of an aggregate retained on the 4.75 mm (No. 4) sieve and resulting either from natural disintegration and abrasion of rock or processing of weakly bound conglomerate. (See also aggregate, coarse.)
gravel, crushed—the product resulting from the artificial crushing of gravel with a specified minimum percentage of fragments having one or more faces resulting from fracture. (See also aggregate, coarse.)
gravel, pea— screened gravel, most of the particles of which pass a 9.5 mm (3/8 in.) sieve and are retained on a 4.75 mm (No. 4) sieve.
gravity feed—the movement of materials from one container to another container or location by force of gravity.
gravity grouting—see grouting, gravity
gravity soak—method for repair of cracks in horizontal concrete sections by topical application of a low viscosity resin.
green concrete—see concrete, green.
grid foundation—see foundation, grid.
grinding—the removal of thin coatings, mineral deposits, or slight protrusions on a concrete surface with rotating abrasive stones or discs under pressure at right angles to the surface.
grinding, finish—the final grinding of clinker into cement, with calcium sulfate in the form of gypsum or anhydrite generally being added; the final grinding operation required for a finished concrete surface, for example, bump cutting of pavement, fin removal from structural concrete, and terrazzo floor grinding.
grinding aids—see aids, grinding.
grinding medium—see medium, grinding.
grit blasting—abrasive blasting with small irregular pieces of steel or malleable cast iron.
grizzly—a simple, stationary screen or series of equally spaced parallel bars set at an angle to remove oversized particles in processing aggregate or other material.
grog—burned refractory material; usually calcined clay or crushed brick bats.
groove joint—see joint, contraction (preferred term).
groover—a tool used to form grooves or weakened-plane joints in a concrete slab before hardening to control crack location or provide pattern.
grooving—a process in which narrow parallel channels are cut into the surface of a material to improve drainage and skid resistance of surfaces subjected to traffic.
gross vehicle load—the mass of a vehicle plus the mass of any load thereon.
gross volume (of concrete mixers)—in the case of a revolving- drum mixer, the total interior volume of the revolving portion of the mixer drum; in the case of an open-top mixer, the total volume of the trough or pan calculated on the basis that no vertical dimension of the container exceeds twice the radius of the circular section below the axis of the central shaft.
ground-granulated slag—see blast-furnace slag.
ground penetrating radar—see short-pulse radar.
grout—a fluid mixture of cementitious or polymer materials used as a filler for cracks or other voids in concrete or foundations such as soil or rock. (See also grout, neat cement and grout, sanded.)
grout, cementitious—a mixture of cementitious material and water, with or without aggregate, proportioned to produce a pourable consistency without segregation of the constituents.
grout, chemical—any materials, including sodium silicate, acrylate, lignin, urethane, and resin characterized by being a true solution; no particles in suspension. (See also grout, particulate.)
grout, colloidal—grout in which a substantial proportion of the solid particles have the size range of a colloid.
grout, compaction—injection grout with less than 1 in. (25 mm) slump; normally a soil-cement with sufficient silt sizes to provide plasticity and sufficient sand sizes to develop internal friction; generally does not enter soil pores but remains in a homogenous mass that provides controlled displacement to compact loose soils or lift structures, or both.
grout, epoxy—a grout that is a mixture of ingredients consisting of an epoxy bonding system, aggregate or fillers, and possibly other materials.
grout, exothermic—grout that produces heat when the binder and catalyst react; peak exothermic reaction temperature occurs when the grout changes from a liquid to a solid.
grout, expansive-cement—see concrete (mortar or grout) and expansive-cement.
grout, field-proportioned—a hydraulic-cement grout batched at the jobsite using water and predetermined portions of portland cement, aggregate, and other ingredients.
grout, hydraulic-cement—a grout which is a mixture of hydraulic cement, aggregate, water and possibly admixtures.
grout, machine-base—a grout which is used in the space between plates or machinery and the underlying foundation and which is expected to maintain essentially complete contact with the base and to maintain uniform support.
grout, masonry—a mixture of hydraulic cement, aggregate, water and possibly other materials (ASTM C 476), used for filling designated spaces in masonry construction.
grout, neat cement—a fluid mixture of hydraulic cement and water, with or without other ingredients; also the hardened equivalent of such mixture.
grout, organic—grouts that gel or set by chemical reaction. (See also grout, chemical)
grout, particulate—any grouting material characterized by undissolved (insoluble) particles in the mix. (See also grout, chemical.)
grout, preblended—a hydraulic-cement grout which is a commercially available mixture of hydraulic cement, aggregate, and other ingredients, which requires only the addition of water and mixing at the jobsite; sometime termed premixed grout.
grout, sanded—a grout mixture that contains fine aggregates.
grout, sodium silicate—a commonly used chemical grout system based on reacting a silicate solution to form a gel that binds soil or sediment particles and fills voids.
grout, water-activated—a class of injection grouts that react with water to form polyurethane polymers.
groutability—the ability of a formation to accept grout.
grout cap—a cap that is formed by placing concrete along the top of a grout curtain; often used in weak foundation rock to secure grout nipples, control leakage, and form an impermeable barrier at the top of a grout curtain.
grout gallery—an opening within a dam used for grouting or drainage operations.
grout header—a pipe assembly attached to a ground hole, and to which lines for injecting grout are attached; sometimes called a grout manifold.
grout injection—the process of pumping grout under pressure to fill cracks, and voids.
grout mixture—the proportions or amounts of the various materials used in the grout, expressed by weight or by volume.
grout nipple—a short length of pipe installed at the collar of the grout hole to facilitate grout injection.
grout penetrability—a grout property descriptive of its ability to fill a porous mass; primarily a function of lubricity and viscosity.
grout slope—the natural slope of fluid grout injected into preplaced-aggregate concrete.
grout system—combination of materials used in a specified grout mixture.
grout take—the measured quantity of grout injected into a unit volume of formation, or a unit length of grout hole.
grouted-aggregate concrete—see concrete, preplaced-aggregate.
grouted masonry—see masonry, grouted.
grouting—the process of injecting, filling, or displacing a volume with grout. (See also grout.)
grouting, advancing-slope—a grout injection technique that causes the leading edge of a mass of grout to move horizontally through preplaced aggregate.
grouting, backpack—filling the annular space between a permanent tunnel lining and the surrounding formation with grout.
grouting, blanket—a method for reducing the permeability and strengthening the upper layers of bedrock by drilling and grouting shallow, closely spaced holes according to a grid pattern.
grouting, circuit—a grouting method by which grout is circulated through a pipe extending to the bottom of the hole and back up the hole via the annular space outside the pipe, the excess grout being diverted back over a screen to the agitator tank by means of a packing gland at the top of the hole; used where holes tend to cave and sloughing material might otherwise clog openings to be grouted.
grouting, closed-circuit—injection of grout into a hole intersecting fissures or voids that are to be filled at such volume and pressure that grout input to the hole is greater than the grout take of the surrounding formation, excess grout being returned to the pumping plant for recirculation.
grouting, containment—see grouting, perimeter.
grouting, contraction-joint—injection of grout into contraction joints.
grouting, control-joint—see grouting, contraction-joint.
grouting, curtain—subsurface injection of grout to create a barrier of grouted material transverse to the direction of anticipated water flow.
grouting, displacement—injection of grout in such a manner as to physically move material adjacent to the point of grout injection. (See also grouting, penetration.)
grouting, envelope—grouting of rock surrounding a hydraulic pressure tunnel to consolidate the rock and reduce permeability of the area.
grouting, gravity—grouting by using only the height of the fluid column to provide pressure.
grouting, high-lift—a technique in masonry wall construction in which the grouting operation is delayed until the wall has been laid up to a full story height.
grouting, injection—a method for sealing or repairing cracks in concrete and filling voids within a concrete structure or foundation.
grouting, jet—technique utilizing a special drill bit with horizontal and vertical high-speed water jets to excavate alluvial soils and produce hard, impervious columns by pumping grout through the horizontal nozzles that jets and mixes with foundation material as the drill bit is withdrawn.
grouting, low-lift—a technique of masonry wall construction in which the wall sections are built to a height of not more than 5 ft (1.7 m) before the cells of the masonry units are filled with grout.
grouting, open-circuit—a grouting system with no provision for recirculation of grout to the pump.
grouting, penetration—filling joints or fractures in rock or pore spaces in soil with a grout without disturbing the formation; this grouting method does not modify the solid formation structure. (See also grouting, displacement.)
grouting, perimeter—injection of grout, usually at relatively low pressure, around the periphery of an area which is subsequently to be grouted at greater pressure; intended to confine subsequent grout injection within the perimeter.
grouting, permeation—filling joints or fractures in rock or pore spaces in soil with a grout, without disturbing the formation.
grouting, series—similar to stage grouting, except each successively deeper zone is grouted by means of a newly drilled hole, eliminating the need for washing grout out before drilling the hole deeper.
grouting, slush—application of cement slurry to surface rock as a means of filing cracks and surface irregularities or to prevent slaking; also applied to riprap to form grouted riprap.
grouting, staged—sequential grouting of a hole in separate steps or stages in lieu of grouting the entire length at once; holes may be grouted in ascending stages by using packers or in descending stages downward from the collar of the hole.
guideline—a written statement of policy or procedure.
gun—(1) shotcrete material delivery equipment, usually consisting of double chambers under pressure; equipment with a single pressure chamber is used to some extent (see also gun, cement); or (2) pressure cylinder used to propel freshly mixed concrete pneumatically.
gun, cement—a machine for pneumatic placement of mortar or small aggregate concrete; in the “Dry Gun,” water from a separate hose meets the dry material at the nozzle of the gun; with the “Wet Gun,” the delivery hose conveys the premixed mortar or concrete. (See also shotcrete.)
gun casting—a procedure in which concrete or mortar is placed with a special velocity-reducing casting head and standard shotcrete delivery equipment.
gun finish—see finish, gun.
Gunite—a proprietary term for shotcrete.
gunman—workman on shotcreting crew who operates delivery equipment.
gunning—act of applying shotcrete; ejection of material from nozzle and impingement on surface to be gunned.
gunning pattern—(1) conical outline of material discharge stream in shotcrete operation; (2) the sequence of gunning operations to insure complete filling of the space, total encasement of reinforcing bars, easy removal of rebound, and thickness of shotcrete layers.
gypsum—see calcium sulfate.
gypsum concrete—see concrete, gypsum.
gypsum plaster—plaster made with plaster of paris. (See plaster and plaster of paris.)