Concrete and paving glossary - C

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Caisson

A 10" or 12" diameter hole drilled into the earth and embedded into bedrock 3 to 4 feet. The structural support for a type of foundation wall, porch, patio, monopost, or other structure. Two or more "sticks" of reinforcing bars (rebar) are inserted into and run the full length of the hole and then concrete is poured into the caisson hole. A caisson is designed to rest on an underlying stratum of rock or satisfactory soil and is used when unsatisfactory soil exists. See rebar and pouring.

Calcite

The main raw material used in the manufacture of Portland cement. Calcite is a crystallized form of calcium carbonate and is the principal component in limestone, chalk, and marble.

Calcium aluminate cement

A combination of calcium carbonate and aluminates that have been thermally fused or sintered and ground to make cement.

Calcium chloride

An additive used in ready-mix to accelerate the curing, usually used during damp conditions. See ready-mixed concrete.

Capillary space

A term used to describe air bubbles that have become embedded in cement paste.

Cast-in-place concrete

Concrete that is poured into forms that are erected at the job site. It is the same as the term sitecasting. See pre-cast concrete.

Casting

Pouring a liquid material, or slurry, like concrete, into a mold or form whose physical form it will take on as it solidifies. See pouring.

Casting bed

A permanent, fixed form, in which permanent pre-cast concrete forms are produced. See pre-cast concrete, cast-in-place concrete.

Cefi

A contraction meaning a cement finisher.

Cem. Fin.

The construction abbreviation for a cement finish.

Cement

A material composed of fine ground powders that hardens when mixed with water. Cement is only one component of concrete. The gray powder that is the "glue" in concrete.

Cement-aggregate ratio

The ratio of cement to aggregate in a mixture, as determined by weight or volume.

Cement content / cement factor

A quantity of cement contained in a unit volume of concrete or mortar, ordinarily expressed as pounds, barrels, or bags per cubic yard.

Cement mixer

A concrete mixer. A container used to mix concrete ingredients by means of paddles or a rotary motion. The container may be manually or power-operated.

Cement mixtures

Mixtures are always listed as parts Cement to Sand to Aggregate. Following are typical cement mixtures description:

• Rich - 1 part cement, 2 parts sand, 3 parts coarse aggregate. A rich mix is used for concrete roads and waterproof structures.

• Standard - 1 part cement, 2 parts sand, 4 parts coarse aggregate. A standard mix is used for reinforced work floors, roofs, columns, arches, tanks, sewers, conduits, etc.

• Medium - 1 part cement, 2 1/2 parts sand, 5 parts coarse aggregate. A medium mix is used for foundations, walls, abutments, piers, etc.

• Lean - 1 part cement, 3 parts sand, 6 parts coarse aggregate. A lean mix is used for all mass concrete work, large foundations, backing for stone masonry, etc.

Cement slurry

A thin, watery cement mixture for pumping or for use as a wash over a surface.

Cement types

• Type I Normal - is a general purpose cement suitable for practically all uses in residential construction but should not be used where it will be in contact with high sulfate soils or be subject to excessive temperatures during curing.

• Type II Moderate - is used where precaution against moderate sulfate attack is important, as in drainage structures where sulfate concentrations in groundwater's are higher than normal.

• Type III High Early Strength - is used when high strengths are desired at very early periods, usually a week or less. It is used when it is desirable to remove forms as soon as possible or to put the concrete into service quickly.

• Type IV Low Heat - is a special cement for use where the amount and rate of heat generated during curing must be kept to a minimum. The development of strength is slow and is intended in large masses of concrete such as dams.

• Type V Sulfate Resisting - is a special cement intended for use only in construction exposed to severe sulfate action, such as western states having soils of high alkali content.

Cementitious

Any material having cementing properties, usually referring to substances like Portland cement and lime. See Portland cement.

Central plant

A facility that makes and distributes ready-mix or pre-mixed concrete loading the material into agitator trucks. See ready-mixed concrete and agitator trucks.

Chair

A small metal or plastic support for reinforcing steel in concrete construction. The support is used to maintain proper positioning during concrete placement. See bar support/bar chair and high chair.

Cinder block

A masonry block made of crushed cinders and Portland cement. This type of block is lighter and has a higher insulating value than concrete. Because moisture causes deterioration of cinder block, it is used primarily for interior rather than exterior walls. See concrete block.

Clinker

The resulting admixture from burning a combination of limestone with silica, alumina, and iron oxide-containing materials. A lump or ball of the fused material, usually 1/8" to 1" in diameter, is formed by heating cement slurry in a kiln. Clinker, when cool, is ground into a fine powder and interground with gypsum to form cement. See admixture.

Clip ties

Sharp, cut metal wires that protrude out of a concrete foundation wall (that at one time held the foundation form panels in place).

Coarse aggregate

Naturally occurring, processed or manufactured, inorganic particles in prescribed gradation or size range. The smallest size particle will be retained on the No. 4 sieve.

Cold joint

A visible line that forms when the placement of concrete is delayed. The concrete in place hardens prior to the next placement of concrete against it.

Cold-rolled solid steel form pins

Concrete forming metal pins made from steel that has been rolled to its final form at a temperature at which it is no longer plastic giving the pins a dense, smooth, surface finish and high tensile strength. See hot-rolled solid steel form pins.

Column clamp

A latching device for holding the sections of a concrete-column form together while the concrete is being placed.

Column form

Specialized forms for creating low height columns typically used as parking lot light anchors, communication tower bases, and similar applications where short columns are required.

Compaction

The elimination of voids in construction materials, as in concrete, plaster, or soil, by vibration, tamping, rolling, or some other method or combination of methods. The process of eliminating voids in the non-set concrete mixture that has been placed often using various vibration devices. A sister operation to placing, compaction rates should be about equal to the time it takes to place. See placing and rodding.

Composite construction

Any element in which concrete and steel, other than reinforcing bars, work as a single structural unit. See rebar.

Compressive strength

The ability of a structural material to withstands squeezing forces. The maximum compressive stress which material, Portland cement, concrete, or grout is capable of sustaining.

Concrete

Concrete is a hardened building material created by combining a mineral (which is usually sand, gravel, or crushed stone) a binding agent (natural or synthetic cement), chemical additives, and water. It is an excellent material to be used in road building, bridges, airports, factories, waterways and other construction projects. Concrete is the mixture of Portland cement, sand, gravel, and water used to make garage and basement floors, sidewalks, patios, foundation walls, etc. It is commonly reinforced with steel rods (rebar) or wire screening (mesh). See binder, cement, Portland cement, and rebar.

Concrete block

A concrete masonry unit, most often hollow, that is larger than a brick. See concrete masonry unit (CMU).

Concrete contraction

The shrinkage of concrete that occurs as it cures and dries. See shrinkage.

Concrete finish

A description of the smoothness, texture, or hardness of a concrete surface. Floors are trowelled with steel blades to compress the surface into a dense protective coat. See trowel, troweling, and trowel finish.

Concrete finishing machine

A portable machine with large paddles like fan blades used to float and finish concrete floors and slabs. A large power-driven machine mounted on wheels that ride on steel pavement forms. These machines are used to finish concrete pavements. See float and finishing.

Concrete masonry unit (CMU)

A block of hardened concrete, with or without hollow cores, designed to be laid in the same manner as a brick or stone. A CMU is also referred to as a concrete block. See concrete block.

Concrete mixture

The percentage of cement content contained in the concrete. A rich mixture contains a high proportion of cement. A lean mixture is a mixture of concrete or mortar with a relatively low cement content. A harsh mixture of concrete is one without mortar or aggregate fines, resulting in an undesirable consistency and workability. See aggregate, cement, cement content/cement factor, cement mixtures, cement types.

Concrete transporting

The process of moving the concrete mixture from the central plant, or mixing location, to the construction site. Transporting devices include agitator trucks, buckets, wheelbarrows, conveyors, and pumping devices. See agitator truck.

Connector bolts

(1) Fastening devices used to connect forms and forming accessories. The typical style is a slotted bolt with a locking wedge so concrete residue cannot form on standard bolt.

(2) Bolts designed with vertical slots used in conjunction with a small metal wedge to attach two flatwork forms together during stacking use. See flatwork forms, flexible forms, stacking, and straight forms.

Consistency

The degree of plasticity of fresh concrete or mortar. The normal measure of consistency is slump for concrete and flow for mortar. See slump and slump test.

Consolidation

Compaction usually accomplished by vibration of newly placed concrete to minimum practical volume, to mold it within form shapes and around embedded parts and reinforcement, and to eliminate voids other than entrained air.

Construction joint

The contact between the placed concrete and concrete surfaces, against or upon which concrete is to be placed and to which new concrete is to adhere, that has become so rigid that the new concrete cannot be incorporated integrally by vibration with that previously placed. Unformed construction joints are placed horizontally or nearly horizontally.

Contractor

A person or company licensed to perform certain types of construction activities that undertakes a legal obligation to perform specified construction work. Types of contractors include:

• General contractor - responsible for the execution, supervision and overall coordination of a project and may also perform some of the individual construction tasks. Most general contractors are not licensed to perform all specialty trades and must hire specialty contractors for such tasks, e.g. electrical, plumbing.

• Remodeling contractor - a general contractor who specializes in remodeling work.

• Specialty contractor - licensed to perform a specialty task e.g. electrical, side sewer, asbestos abatement.

• Sub contractor - a general or specialty contractor who works for another general contractor.

Control joint

Tooled, straight grooves made on concrete floors to "control" where the concrete should crack.

Corner forms

Metal concrete forms that are specialized forming accessories that are attached to straight forms to form 90° corners. Typical applications for corner forms include patios, sidewalks, warehouse floors, slab on grade house foundations, and similar flatwork applications. See slab on grade and straight forms.

Cream

Construction slang term to describe the cement and sand component of ready-mix that rises when the aggregate is worked down by way of agitation – floating, troweling, screeding, etc. This is also referred to as "juice". See float, floating, ready-mixed concrete, screed, screeding, trowel, and troweling.

Curb and gutter

The border area of a street, or other paved surface, that includes a curb, an extruded or hand-formed berm, and a gutter, the area designed to remove and transport water away from the main paved area. Both parts are usually made out of concrete. See curb and gutter combination and curb and gutter forms.

Curb and gutter accessories

Forming components, specialized tools, and attachments that are used to facilitate curb and gutter placement and include hangers, bracing, stake pullers, filler forms, form stakes, form pins, and curbface mules.

Curb and gutter combination

Refers to curbs and gutter combinations that are formed in the same concrete pour. The curb portion varies from 4" to 12" in height and is used to prevent vehicles from leaving a paved area. The gutter portion varies from 6" to 12" in width and is used to control water runoff from pavement. The elevation of the gutter is either slightly above, or slightly below, the grade of the pavement. Additionally, the gutter itself will have a slight inward or outward slant to direct the flow of water either towards or away from the curb, dependent on the desired water flow. See pouring, pitch-in, and pitch-out.

Curb and gutter face forms

Metal forms used in placing concrete that attach to the curb and gutter system to form the profile for the curbface.

Curb and gutter forms

Concrete forms and accessories used to pour a curb and gutter combination. The curb and gutter forming systems consists of a back form, a face form, a front form, a division plate and a top spreader. Back and front forms are standard straight forms with the back form taller than the front form for a curb and gutter combination configuration. See division plate, straight forms, and top spreader.

Curbface batter

Curbface batter refers to the distance between the top slope of a curbface and the bottom slope of a curbface. See batter.

Curbface mule

A mechanical tool used to form the desired curb profile for any curb and gutter application. See curb and gutter forms.

Curbface tool

A hand tool made to match the profile of the curbface used to finish and smooth the curbface after concrete placement, but before concrete hardening. See mule.

Curbface transition forms

Curbface transition forms allow a contractor to quickly change from a straight to a radius curb and back to a straight curb. They usually come in male/female pairs.

Cure

Method of maintaining sufficient internal humidity and proper temperature for freshly placed concrete to assure proper hydration of the cement, and proper hardening of the concrete. See hydration.

Curing

The hardening of concrete, plaster, or other wet material. Curing typically occurs through the evaporation of water or a solvent, hydration, polymerization, or chemical reactions of various types. It is the final process, after placing and compacting, that ensures the concrete will set to its desired strength. The length of time is dependent upon the type of cement, mix proportion, required strength, size and shape of the concrete section, weather and future exposure conditions. The period may be 3 weeks or longer for lean concrete mixtures used in structures such as dams or it may be only a few days for richer mixes. Favorable curing temperatures range from 50° to 70° F. Design strength is achieved in 28 days. See cement mixture, compaction, hydration, and set.

The American Concrete Institute defines curing as maintaining satisfactory moisture content and temperature in concrete during its early stages so that it may obtain the desired properties. See placing and compaction.

Curing blanket

A layer of straw, burlap, sawdust, or other suitable material placed over fresh concrete and moistened to help maintain humidity and temperature for proper hydration. See burlap, curing, curing compound, and curing membrane.

Curing compound

A chemical applied to the surface of fresh concrete to minimize the loss of moisture during the first stages of setting and hardening. See curing, curing membrane, and curing blanket.

Curing membrane

Any of several kinds of sheet material or spray-on coatings used to temporarily retard the evaporation of water from the exposed surface of fresh concrete, thus ensuring a proper cure. See burlap, curing, curing compound, and curing blanket.

Custom forms

A variety of unique forms used for specialized concrete forming such as reversible forms, super flat forms, tilt-up forms, tilt-up reversible forms, foundation set forms, seawall forms, rehab forms, and column forms.

Cut and fill

A term used to describe the addition or subtraction from a grade mark. Also, an operation commonly used in road building and other rock and earthmoving operations in which the material excavated and removed from one location is used as fill material at another location.

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