Concrete and paving glossary - B

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Backfill

The replacement of excavated earth into a trench around or against a basement crawl space foundation wall.

Bag

A quantity of Portland cement; 94 pounds in the United States, 87.5 pounds in Canada, 112 pounds in the United Kingdom, and 50 kilograms in most other countries. Different weights per bag are commonly used for other types of cement. Same as sack.

Ball test

A test to determine the consistency of freshly mixed concrete by measuring the depth of penetration of a cylindrical metal weight or plunger that has been dropped into it. See slump test.

Ballast

A layer of coarse stone, gravel, slag, etc., over which concrete is placed.

Band

A group of small bars or the wire encircling the main reinforcement in a concrete structural member to form a peripheral tie. A band is also a group of bars distributed in a slab, wall, or footing.

Bar

A deformed steel member used to reinforce concrete. See rebar and reinforced concrete.

Bar support (bar chair)

A rigid device of formed wire, plastic, or concrete, used to support or hold reinforcing bars in proper position during concrete operations. See chair and high chair.

Barrel

A unit of weight measure for Portland cement, equivalent to four bags or 376 pounds. See bag.

Base course / base

A layer of material of specified thickness constructed on the subgrade or sub-base of a pavement to serve one or more functions, such as distributing loads, providing drainage, or minimizing frost action. See sub-base.

Batch

The quantity produced as the result of one mixing operation, as in a batch of concrete.

Batch box

A container of known volume used to measure the constituents of concrete or mortar in proper proportions.

Batch mixer

A machine that mixes concrete, grout, or mortar in batches in accordance to a design mix. Each batch is used completely before a second batch is started.

Batch plant

A temporary concrete mixing plant usually erected at a jobsite to fulfill the specific needs of that job. They are typically erected when a large volume of concrete will be required at a specific job. Batch plant utilization reduces transportation costs, increases control of the mixture, and speeds up job completion.

Batter

A slope, such as that of the outer side of a wall, that is wider at the bottom than at the top. The measurement of batter is the horizontal distance between the top and bottom of a slope. See curb face batter.

Batter level

An instrument used to measure the inclination of a slope. See batter.

Battered wall

A wall that slopes backward, as by recessing or sloping masonry in successive courses.

Bedding

A prepared base for masonry or concrete.

Beetle

See maul.

Bending schedule

A list of reinforcement prepared by the designer or detailer of a reinforced concrete structure which shows the shapes, dimensions, and location of every bar, and the number of bars required. See reinforced concrete and rebar.

Bg cement

A bag of cement.

Binder

Almost any cementing material, either hydrated cement or a product of cement or lime and reactive siliceous materials. The kinds of cement and the curing conditions determine the general type of binder formed. Any material, such as asphalt or resin, that forms the matrix of concretes, mortars, and sanded grouts.

Bituminous cement

A class of dark substances composed of intermediate hydrocarbons. Bituminous cement is available in solid, semisolid, or liquid states at normal temperatures.

Blaine apparatus

Air-permeability apparatus for measuring the surface area of a finely ground cement. See Blaine fineness and Blaine test.

Blaine fineness

The fineness of granular materials such as cement and pozzolano, expressed as total surface area in square centimeters per gram, determined by the Blaine air-permeability apparatus and procedure. See Blaine apparatus, Blaine test, and pozzolano.

Blaine test

A method for determining the fineness of cement or other material based on the permeability to air of a sample prepared under specified conditions. See Blaine apparatus and Blaine fineness.

Blanket

Insulation sandwiched between sheets of fabric, plaster, or paper facing, used for protecting fresh concrete during curing. See curing.

Bleeding

The autogenous flow of mixing water within, or its emergence from, freshly placed concrete or mortar. Bleeding is caused by the settlement of the solid materials within the mass. Bleeding is also called water gain.

Blended cement

A hydraulic cement consisting of an intimate and uniform blend of granulated blast-furnace slag and hydrated lime, Portland cement and granulated blast-furnace slag, Portland cement and pozzolano, or Portland-blast-furnace slag, cement, and pozzolano. Blended cement is produced by intergrinding Portland cement clinker with the other materials or by a combination of intergrinding and blending. See hydraulic cement, Portland cement, and pozzolano.

Block out

The installing of a box or barrier within a foundation wall to prevent the concrete from entering an area. For example, foundation walls are sometimes "blocked" in order for mechanical pipes to pass through the wall, to install a crawl space door, and to depress the concrete at a garage door location.

Blowhole

In concrete, a bug hole or small regular or irregular cavity, not exceeding 15 mm in diameter, resulting from entrapment of air bubbles in the surface of formed concrete during placement and compaction. See placing, placement and compaction.

Blowout

Term used when the ready-mixed concrete breaks through the forming boards due to insufficient bracing. Also, the localized buckling or breaking up of rigid pavement as a result of excessive longitudinal pressure. See ready-mixed concrete.

Blowup

Slang term used to describe the unexpected fast setting of concrete that does not allow proper finishing. See set.

Board foot

The basic unit of measurement for lumber. One board foot is equal to a 1" thick board, 12" in width and 1' in length. Therefore, a 10' long, 12" wide, and 1" thick piece contains 10 board feet. Nominal sizes are assumed when calculating board feet.

Bond

The adhesion of cement paste to aggregate and or the rebar. See aggregate and rebar.

Bond breaker

A strip of material to which the cement does not adhere. See bond and form release agent.

Bonded posttensioning

A process in posttensioned construction whereby the annular spaces around the tendons are grouted after stressing in a manner that the tendons become bonded to the concrete section.

Brace/bracing

A concrete forming accessory that acts as a temporary support for aligning vertical concrete formwork. One end of the brace attaches to the form and the other anchors to the ground.

British thermal unit (BTU)

A standard measurement of the heat energy required to raise the temperature of one pound of water one degree Fahrenheit.

Brittle

A material that fractures easily such as cement.

Broom finish

Concrete that has been brushed with a broom when fresh in order to improve its traction or to create a distinctive fine-lined texture.

Brown millerite

An oxide of calcium, aluminum, and iron commonly formed in Portland cement and high alumina cement mixtures.

Bull float

A board of wood, aluminum, or magnesium mounted on a pole and used to spread and smooth freshly placed, horizontal concrete surfaces. After screeding, the first stage in the final finish of concrete, smoothes and levels hills and voids left after screeding. Sometimes substituted for darbying. See darby, float, and screeding.

Burlap

Material often used to protect newly finished concrete from rain as well as maintaining moisture in a slab. See Visqueen and curing blanket.

Burn

A construction slang term used to describe the darkish concrete color that occurs as a result of over troweling. See trowel, troweling, and trowel finish.

Bush-hammer

A tool having a serrated face, as rows of pyramidal points, used to develop an architectural finish for concrete surfaces.

Bush-hammered concrete

Concrete with an exposed aggregate finish that has been obtained by removing the surface cement using a percussive hammer with a serrated face. See aggregate, exposed.

Butterfly

A hand tool used to trowel finish concrete curb and gutter work. See trowel, troweling, trowel finish, and curb and gutter.

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