hacking the roughening of a surface by striking with a tool.
hairline crack see crack, hairline.
hairpin the wedge used to tighten some types of form ties; a hairpin-shaped anchor set in place while concrete is unhardened; a light hairpin-shaped reinforcing bar used for shear reinforcement in beams, tie reinforcement in columns, or prefabricated column shear heads.
Hamm tip flared shotcrete nozzle having a larger diameter at midpoint than at either inlet or outlet; also designated premixing tip.
hammer, impact see hammer, rebound (preferred term).
hammer, rebound an apparatus that provides a relative indication of the strength or hardness of concrete based on the rebound distance of a spring-driven mass after it impacts a rod in contact with the concrete surface.
hammer, Schmidt see hammer, rebound (preferred term).
hammer, Swiss see hammer, rebound (preferred term).
hanger a device used to suspend one object from another object. (See also beam hanger.) History
hanger, form device used to support formwork from a structural framework; the dead load of forms, mass of concrete, and construction and impact loads must be supported.
hard-burned dolomite see dolomite, hard-burned.
hard-burned lime see lime, hard-burned.
hardened concrete see concrete, hardened.
(1) a chemical (including certain fluosilicates or sodium silicate) applied to concrete floors to reduce wear and dusting; or
(2) in a two-component adhesive or coating, the chemical component that causes the resin component to cure.
Hardy Cross method see moment distribution.
harped tendons see tendons, deflected (preferred term).
harsh mixture see mixture, harsh.
haunch a deepened portion of a beam in the vicinity of a support.
(1) concrete support to the sides of a drain or sewer pipe above the bedding; or
(2) work done in strengthening or improving the outer strip of a roadway.
hawk a tool used by plasterers to hold and carry plaster mortar; generally a flat piece of wood or metal approximately 10 to 12 in. (0.25 to 0.3 m) square, with a wooden handle centered and fixed to the underside. (See also hod and mortar board.)
header a masonry unit laid flat with its greatest dimension at a right angle to the face of the wall; when the unit is only the depth of the face wythe it is known as a false header. [See also bonder and wythe (leaf).]
header, false see header.
healing, autogenous a natural process of filling and sealing cracks in concrete or in mortar when kept damp.
heat-deflection temperature see temperature, heat-deflection.
heat of hydration heat evolved by chemical reactions with water, such as that evolved during the setting and hardening of portland cement, or the difference between the heat of solution of dry cement and that of partially hydrated cement. (See also heat of solution.)
heat of solution heat evolved or absorbed when a substance is dissolved in a solvent.
heat-resistant concrete see concrete, heat resistant.
heating rate the rate expressed in degrees per hour at which the temperature is raised to the desired maximum temperature.
heavy concrete see concrete, high-density (preferred term).
heavy-edge reinforcement see reinforcement, heavy-edge.
heavy-media separation see separation, heavy-media.
heavyweight aggregate see concrete, high-density (preferred term).
heavyweight concrete see concrete, high-density.
helical reinforcement see reinforcement, helical.
hematite a mineral, iron oxide (Fe2O3) used as aggregate in high density concrete and in finely divided form as a red pigment in colored concrete.
hemihydrate a hydrate containing one-half molecule of water to one molecule of compound, the most commonly known hemihydrate is partially dehydrated gypsum (also known as plaster of paris), CaSO4·1/2H2O. (See also bassanite.)
hesitation set see set, false (preferred term).
Hessian see burlap (preferred term).
high-alumina cement see cement, calcium-aluminate (preferred term).
high-bond bar see bar, deformed.
high-density concrete see concrete, high-density.
high-discharge mixer see mixer, inclined-axis (preferred term).
high-early-strength cement see cement, high-early-strength.
high-fineness cement see cement, high-fineness.
high-early-strength concrete see concrete, high-early-strength.
high-lift grouting see grouting, high-lift.
high-performance concrete see concrete, high-performance.
high-pressure steam curing see curing, autoclave (preferred term).
high-range water-reducing admixture see admixture, water-reducing (high-range).
high-strength concrete see concrete, high-strength.
high-strength reinforcement see steel, high-strength.
high-strength steel see steel, high-strength.
high-temperature steam curing see curing, atmospheric-pressure steam and curing, autoclave.
hinge, Mesnager a permanent semiarticulation or flexible joint in a reinforced-concrete arch, wherein the angles of rotation at the hinge are very small; by crossing steel reinforcing bars within the opening between the concrete structural segments, the resultant articulation presents very small resistance to rotation, resists either axial thrust or shearing forces, and is permanently flexible; the center of rotation occurs at the intersection of the reinforcing bars.
hinge, plastic region where ultimate moment capacity in a member may be developed and maintained with corresponding significant inelastic rotation as main tensile steel elongates beyond yield strain.
hinge joint see joint, hinge.
hod a V-shaped trough or a tray, supported by a pole handle that is borne on the carriers shoulder, for carrying small quantities of brick, tile, mortar, or similar load. (See also hawk and mortar board.)
hold-down bolt see bolt, anchor (preferred term).
holding period see period, presteaming (preferred term).
hollow-unit masonry see masonry, hollow-unit.
honeycomb voids left in concrete due to failure of the mortar to effectively fill the spaces among coarse-aggregate particles.
hook a bend in the end of a reinforcing bar.
hooked bar see bar, hooked.
Hookes law see law, Hookes.
hoop reinforcement see reinforcement, hoop.
horizontal-axis mixer see mixer, horizontal-axis.
horizontal-shaft mixer see mixer, horizontal-shaft.
horizontal shoring see shoring, horizontal.
hose, delivery hose through which shotcrete, grout, or pumped concrete or mortar passes; also known as conveying hose or material hose.
hot cement see cement, hot.
hot face the surface of a refractory section exposed to the source of heat.
hot-load test see test, hot-load.
Hoyer effect in pretensioned, prestressed concrete, frictional forces that result from the tendency of the tendons to regain the diameter which they had before they were stressed.
hydrate a chemical combination of water with another compound or an element.
hydrate, calcium-silicate any of the various reaction products of calcium silicate and water. (See also dicalcium silicate, tricalcium silicate.)
hydrated lime see lime, hydrated.
hydration formation of a compound by combining water with some other substance. In cementitious materials, the chemical reaction between hydraulic cement and water. History
hydraulic cement see cement, hydraulic.
hydraulic-cement grout see grout, hydraulic-cement.
hydraulic hydrated lime see lime, hydraulic hydrated.
hydrochloric acid a mineral acid sometimes used for cleaning or acid etching concrete or removing efflorescence; also known as muriatic acid, which is a 33% HCl solution.
hydromix nozzle a shotcrete hose and nozzle configuration used in place of a predampening system to introduce pressurized water into the material stream via a water ring located approximately 3 m (10 ft) upstream of the nozzle tip. The nozzleman can control the amount of water introduced to the material stream via a control valve near the nozzle tip. History
hydrophobic cement see cement, hydrophobic.
hydrous calcium chloride see calcium chloride, hydrous.
|
|