Concrete Flashcards
A naturally occuring clayey limestone that, when calcined and finely pulverized, produces a hydraulic cement.
Natural Cement
A siliceous material, such as fly ash, that reacts chemically with slaked lime in the presence of moisture to form a slow-hardening cement, named after a natural cement from Pozzuoli, an ancient Roman town near Vesuvius.
Pozzolan also Pozzolona, Pozzuolana
Containing silica or silicate.
Siliceous
Fine Particles of ash recovered from the waste gases of a solid-fuel furnace.
Fly Ash
A calcined mixture of clay and limestone, finely pulverized and used as an ingredient in concrete and mortar. The term is frequently used incorrectly for concrete.
Cement
A compound constituting about half the volume of portland cement and responsible for the hardening or early gain in strength of the cement.
Tricalcium Silicate
A compound constituting about one-quarter of the volume of portland ecment and responsible for the aging or long-term gain in strength of the cement.
Dicalcium Silicate
A compound constituting about one tenth of the volume of portland cement and responsible for the initial setting of the cement.
Tricalcium Aluminate
A hydraulic cement made by burning a mixture of clay and limestone in a rotary kiln and pulverizing the resulting clinker into a very fine powder, named for its resemblance to a limestone quarried on the Isle of Portland, England.
Portland cement
Cement capable of setting and hardening by a reaction with water.
Hydraulic Cement
A portland cement used for general construction, havin none of the distinguishing qualities of the other types.
Type 1 - Normal
A portland cement having a reduce content of tricalcium aluminate, making it more resistant to sulfates and causing it to generate less heat of hydration; used in general construction where resistance to moderate sulfate action is required or where heat buildup can be damaging, as in the construction of large piers and heavy retaining walls.
Type II - Moderate
A very finely ground portland cement having an increased content of tricalcium silicate, causing increased content of tricalcium silicate, causing it to cure faster and gain strength earlier than normal portland cement; used when the early removal of formwork is desired, or in cold-weather construction to reduce the time required for protection from low temperatures.
Type III - High Early Strength
A portland cement having a reduced content of tricalcium silicate and an increased content of dicalcium silicate, causing it to generate less heat of hydration than normal portland cement; used in the construction of massive concrete structures, such as gravity dams, where a large buildup in heat can be damaging.
Type IV - Low Heat
A portland cement having a reduced content of tricalcium aluminate, lessening the need for gypsum, a sulfate normally added to cement to retard its detting time; used where resistance to severe sulfate action is required.
Type V - Sulfate Resisting
A type I, Type II, or Type III portland cement to which a small quantity of an air-entraining agent has been interground during manufacture: designated by the suffix A, as in Type IA, Type IIA, or Type IIIA.
Air-entraining portland cement
A portland cement produced from raw materials low in iron oxide and manganese oxide, the substances that give concrete its gray color, used in precast concrete work and in the making of terrazzo, stucco and tile ground.
White portland Cement
An expansive reaction occurring when the cement matrix of concrete or mortar comes in contact with sulfates dissolved in ground water or in soil.
Sulfate action
Microscopic, spherical air bubbles, typically .004 to .04 inches (.1 to 1mm) in diameter intentionally dispersed in a concrete or mortar mix by an air-entraining agent.
Entrained Air
A fused mass of incombustible matter resulting from heating in a kiln or the burning of coal.
Clinker
To heat a substance to a high temperature but without melting or fusing to drive off volatile matter or to cause oxidation or reduction
Calcine
Aggregate consisting of sand having a particle size smaller than 1/4” (6.4mm), specif. te portion of aggregate that will pass through a 3/8” (9.5mm) sieve, almost entirely through a No. 4 (4.8mm) sieve, and be predominantly retained on a No. 200 (74u) sieve.
Fine Aggregate
Aggregate consisting of crushed stone, gravel or blast-furnace slag having a particle size larger than 1/4” (6.4mm); specif. the portion of aggregate that is retained on a No. 4 (4.8mm) sieve. The maximum size of coarse aggregate in reinforced concrete is limited by the size of the section and the spacing of the reinforcing bars.
Coarse Aggregate
Aggregate having a particle-size distribution characterized by uniform grading. Graded aggregate requires the least amount of cement paste to fill the voids and surround the particles.
Graded Aggregate
The range of particle sizes in a granular material, expressed either as the cumulative percentage by weight of particles smaller or larger than a specified sieve opening, or as the percentage by weight of the particles that range between specified sieve openings.
Particle-Size Distribution
A particle-size distribution in which aggregate particles vary uniformly from fine to coarse without a preponderance of any one size or group sizes.
Uniform Grading
The water used in a concrete or mortar mix, exclusive of any absorbed by the aggregate and free of such harmful substanes as organic material, clay and salts. Water fit for drinking is generally acceptable.
Mixing Water
A mixture of cement and water for coating, setting and binding the aggregate particles together in a concrete or mortar mix.
Cement Paste
Any of various hard, inert, mineral materials, such as sand and gravel, added to a cement paste to make concrete or mortar. Since aggregate represents from 60% to 80% of the concrete volume, its properties are important to the strength, weight and fire-resistance of the hardened concrete. Aggregate should be hard, dimensionally stable and free of clay, silt, and organic matter, which can prevent the cementing matrix from binding the particles together.
Aggregate
Any substance other than cement, water or aggregate, added to a concrete or mortar mix to alter its properties or those of the hardened product.
Admixture or Additive
An admixture that disperses entrained air in a concrete or mortar mix to increase workability, improve resistance of the cured product to the cracking induced by free-thaw cycles or the scaling caused by deicing chemicals, and in larger amounts, to produce lightweight insulating concrete.
Air-entraining agent
An admixture that hastens the setting and strength develpment of a concrete, mortar, or plaster mix.
Accelerator
An admixture that slows the setting of a concrete, mortar or plaster mix in order to allow more time for placing and working the mix.
Retarder
An admixture for reducing the surface tension of the mixing water in a concrete mix, thereby facilitating the wetting and penetrating action of the water or aiding in the emulsifying and dispersion of other additives in the mix.
Surface Active Agent or Surfactant
An admixture for reducing the amount of mixing water required for the desired workability of a concrete or mortar mix. Lowering the water-cement ratio in this manner generally results in increased strength.
water-reducing agent or Superplasticizer
A pigment or dye added to a concrete mix to alter or control its color.
Coloring Agent
A strong lightweight aggregate obtained by the exfoliation of clay or shale.
Expanded Shale or Expanded Clay
A strong lightweight aggregate obtained by the exfoliation of slate.
Expanded Slate
The splitting or swelling of certain minerals into a scaly aggregate when heated.
Exfoliation
A volcanic glass expanded by heat to form lightweight, spherical particles, used as nonstructural lightweight aggregate and as loose-fill thermal insulation.
Perlite
Mica expanded by heat into very light, wormlike threads, used as nonstructural lightweight aggregate and as loose-fill thermal insulation.
Vermiculite
Concrete made with aggregate of low specific gravity and weighing less than normal concrete, which has a unit weight of about 150pcf (2,400 kg/m3).
Lightweight Concrete
Concrete made with strong lightweight aggregate such as expanded shale or slate, having a unit weight from 85 to 115 pcf(1,362 to 1840kg/m3) and compressive strength comparable to that of normal concrete.
Structural Lightweight Concrete
Lightweight concrete having a unit weight of less than 60pcf(960 kg/m3) and low thermal conductivity, made with lightweight aggregate, such as perlite or with a foaming agent or gas forming chemical that infuses the mix with a homogeneous cellular structure.
Insulating Concrete
The most economical selection and proportioning of cement, water, aggregate to produce concrete or mortar having the required properties of workability, strength, durability, and watertightness.
Mix Design
A law postulating that, with given concrete materials, curing and testing conditions, the compressive strength of concrete is inversely proportional to the ratio of water to cement: developed by D.A. Abrams in 1919 from experiments at Lewis Institute in Chicago.
Abram’s Law
The ratio of mixing water to cement in a unit volume of concrete or mortar mix, preferably expressed by weight as a decimal fraction but often stated in gallons of water per 94lb, sack of cement. The water-cement ratio controls the strength, durability, and watertightness of hardened concrete.
Water-Cement Ratio
A measure of portland cement: 94lb in the US, 87lb in Canada, 112lb in Britain and 50kg in countries using the metric system.
Sack also Called Bag
A measure of the consistency and workability of freshly mixed concrete, expressed as the vertical settling, in inches of a specimen after it has been placed in a slump cone, tamped in a prescribed manner, and the cone is lifted.
Slump
The relative ability of freshly mixed concrete or mortar to flow, usually measured by the slump test for concrete and by the flow test for grout or mortar. Consistency depends largely on the proportion of cement paste to aggregate in a mix.
Consistency
The relative ease with which freshly mixed concrete or mortar can be handled, placed in formwork, compacted, and finished. Workability depends partly on the water-cement ratio and partly on the grading of the aggregate in a mix.
Workability
A concrete or mortar mix that flows sluggishly without segragating and is readily molded.
Plastic Mix
A concrete or mortar mix containing little water or too much aggregate in erlation to the other components and having little or no slump.
Dry Mix
A concrete or mortar mix having a relatively high water content and runny consistency, yielding a product that is low in strength, durability, and watertightness.
Wet Mix
An open-ended, truncated cone of sheet metal, 12in (305mm) high, with a base diameter of 8in (203mm) and a top diameter of 4in(102mm), used to mold a specimen of freshly mixed concrete for the slump test.
Slump Cone
A test for determining the compressive strength of a concrete batch, using a hydraulic press to measure the maximum load a test cylinder can support in axial compression before fracturing.
Compression Test
A cylinder of concre 6in (152mm) in diameter and 12in (305mm) high, cast from a representative batch and cured in a laboratory or in the field under controlled conditions.
Test Cylinder
A compression test of a cylinder cut from a hardened concrete structure, usually by means of a core drill.
Core Test
Core Driller
Material for lining the inside face of a form, specially selected to impart a smooth or patterned finish to the concrete surface.
Form Liner
A brace, usually of wood, for spacing and keeping wall or footing forms apart.
Spreader or Spacer
A horizontal timber or steel beam for reinforcing various vertical members, as in formwork or sheet piling, or for retaining earth at the edge of an embankment.
Waler - also Brease Timber, Ranger, Wale
A vertical support for alighning and reinforcing walers.
Strong back or Stiffback
A partition closing the end of a form or preventing the passage of newly placed concrete at a construction joint.
Bulkhead
A longitudinal groove or channel formed in a concrete footing or other member that has set, providing a shear-resisting key for newly placed concrete.
Keyway
Boarding or sheeting of wood, metal, plastic or fiberglass for containing and giving a desired shape to newly placed concrete until it sets and gains sufficient strength to be self-supporting.
Form
A clamping device for keeping columns forms or the tops of wall forms from spreading under the fluid pressure of newly placed concrete.
Yoke
Trademark for a brand of cylindrical column form made of compressed, resin-impregnated paper.
Sonotube
A strip of wood or other material attached to a form to produce a smooth, rounded or beveled edge on the outside corner of a concrete member.
Chamfer Strip
A strip of wood or other material attached to the inside face of a form to produce a groove in the surface of a concrete member.
Rustication Strip
A wood strip fixed to the inside face of a form to indicate the top of a concrete lift.
Grade Strip
Any of a variety of slotted devices for tightening formwork and transferring the force in a form tie to the walers.
Wedge
A form tie consisting of waler rods that are inserted through the form and threaded onto the ends of an inner rod; after stripping, the waler rods are removed while the inner rod remains in the concrete.
She Bolt
A form tie having notches or crimps, which allow its ends to be snapped off below the concrete surface after stripping of the forms.
Snap Tie
A form tie having cones at each end inside the forms, which allow it to also serve as a spreader.
Cone Bolt
A small, truncated cone of wood, steel, or plastic attached to a form tie to space and spread wall forms, leaving a neatly finished depression in the concrete surface to be filled or left exposed.
Cone
A device for supporting and holding steel reinforcement in proper position before and during the placing of concrete.
Chair
A tall chair for supporting top bars in a concrete beam or slab
High Chair
A wide chair for supporting and spacing bottom bars in a concrete beam or slab.
Bolster
A form that can be raised vertically for succeeding lifts of concrete during the construction of a multistory building.
Climbing Form
The height of a quantity of concrete placed in a form at one time.
Lift
A form that can be moved slowly and continuously as concrete is being placed during the construction of a concrete pavement or building.
Slip Form
A large form that can be moved by a crane, used in constructing the concrete floors and roofs of multistory buildings.
Flying Form
A truck equipped with a rotating rum to prevent segregation or loss of plasticityof the ready-mixed concrete being delivered to a construction site.
Agitator Truck
A truck equipped with a rotating drum and a separate water tank for mixing concrete en routh to a construction site.
Truck Mixer
A cart, often motor-driven, for transporting heavy materials, such as freshly mixed concrete for short distances at a construction site.
Buggy
A machine having a revolving drum, often motor-driven, for mixing cement, aggregate, and water to produce concrete.
Concrete Mixer
The delivery of concrete, slurry, or plaster by a pipeline or hose to the point of placement on a construction iste, either in a plastic state for depositing in place or for spraying, or in a dry state with water added at the nozzle from which it is sprayed.
Pneumatic Placement
A lightweight concrete construction consisting of a mixture of cement, sand or crushed slag, and water, pumped through a hose and sprayed at high velocity over reinforcement until the desired thickness is reached.
Shotcrete or Gunite
A chute for containing and directing a falling stream of freshly mixed concrete so as not to cause segregation.
Drop Chute
An inclined trough or tube for conveying free-flowing materials to a lower level by gravity.
Chute
Consolidation of newly praced concrete by the repeated insertions and withdrawals of a flat, spadelike tool.
Spading
An electric or pneumatic oscilliating tool for agitating and consolidating newly placed concrete.
Vibrator
The separation of coarse aggregate from the mortar or of water from the other ingredients of freshly mixed concrete, resulting from excessiv horizontal movement or free fall of the mix, or from overvibration after placement.
Segregation
The separation of an excessively wet or overvibrated concrete mix into horizontal layers with increasinly lighter material migrating toward the top.
Stratification
The emrgence of excecss mixing water on the surface of newly placed concrete, cause by settlement of solids within the mass.
Bleeding or Water Gain
A milky deposit containing cement and aggregate fines on the surface of new concrete, caused by the bleeding of excess mixing water, overworking of the mix, or improper finishing.
Laitance
A wooden or metal straightedge drawn a over a newly placed concrete slab to bring it to proper level.
Screed
A firmly established grade strip or edge form serving as a guide for making a true level surface on a newly placed concrete slab.
Screed
A flat tool for spreading and smoothing a fresh concrete, stucco, or plaster surface.
Float
A float having a large, flat blade attached to a long handle.
Bull Float
A long wooden or metal straightedge for smoothing a fresh concrete surface immediately after screeding.
Darby
A colored finish produced by sprinkling a dry mixture of cement, sand, and a pigment on a fresh concrete surface following screeding and after any free water has evaporated, and then working the mixture into the surface with a float.
Dry-Shake Finish
Concrete left in its natural state after formwork is removed, especially when the concrete surface reflects the texture, joints, and fasteners of a board form.
Beton Brut
A fine-texture finish obtained by smotthing a fresh conrete, plaster, or stucco surface with a wood float.
Float Finish
A striated finish obtained by stroking a broom or stiff brush over a freshly troweled concrete surface.
Broom Finish
A decorative finish produced by sandblasting, etching with an acid, or scrubbing a concrete surfae after the initial set in order to remove the outer layer of cement paste and expose the aggregate.
Exposed Aggregate Finish
A dense, smooth finish obtained by working a fresh concrete or plaster surface with a steel trowel.
Trowel Finish
A textured finish given to a fresh plaster or concrete surface by trowelling with a circular, overlapping motion.
Swirl Finish
A coarse-textured finish obtained by fracturing a concrete or stone surface with a power-driven hammer having a rectangular head with a corrugate, serrated or toothed face.
Bushhammered finish
Bush Hammer
Riffel Hammer
Any of various flat-bladed hand tools for applying, spreading, working or smoothing plastic material, such as concrete, mortar and plaster.
Trowel
A portable machine having steel trowels mounted on radial arms that rotate about a vertical shaft to smooth, compact, and finish a fresh concrete surface.
Power Trowel
A trowel having a long, curved lip for rounding the edges of a fresh concrete slab as it begins to set
Edger
A wheel-mounted, rotary power saw equipped with a silicon-carbide or diamond blade for cutting a contril joint in a hardened concrete slab.
Pavement Saw
Voids on a formed concrete surface, caused by segragation during placement or by insufficient consolidation.
Honeycomb
The chipping or scaling of a hardened concrete or masonry surface caused by freeze-thaw cycles or the application of deicing salts.
Spalling or Scaling
Numerous hairline cracks occuring in the surface of a newly hardened concrete slab as a result of rapid drying shrinkage.
Crazing
