Pea Gravel Portion of concrete aggregate passing the 3/8' sieve and retained on a No.4 sieve

Plasticizer An admixture that increases the workability or consistency of a concrete mixture, mortar or cement paste

Ready-Mixed Concrete Concrete that is batched at a central plant before it is delivered to a construction site in a concrete mixer.

Rebar The reinforcing bar is essentially ribbed steel bars installed in foundation concrete walls, footers, and poured in place concrete structures designed to strengthen concrete. Rebar comes in various thickness' and strength grade. Rebar is designed to counter stress forces.

Reinforced Concrete Concrete which has additional reinforcing properties added to it, such as rebar or fiber mesh

Retarder An admixture which extends the setting time of cement paste, and therefore of mixtures such as concrete, mortar, or grout

Sand (ASTM C125) That portion of an aggregate passing the No. 4 (4.76 mm) sieve and predominantly retained on the No. 200 (74 micron) sieve

Screed The leveling of concrete to the correct elevation during a concrete pour. A screed is also a tool for striking off the concrete surface.

Screen (or Sieve) A metallic sheet or plate or woven wire cloth with regularly spaced openings, mounted in a suitable frame or holder for use in separating material according to size

Segregation The tendency for the coarse particles to separate from the finer particles in handling. In concrete, the coarse aggregate and drier material remains behind and the mortar and wetter material flows ahead. This also occurs in a vertical direction when wet concrete is over vibrated or dropped vertically into the forms, the mortar and wetter material rising to the top

Set A term describing stiffening of concrete when plasticity is partially lost, usually measured in terms of resistance to deformation.

Shotcrete Mortar or concrete conveyed through a hose and projected pneumatically at high velocity onto a surface; dry-mix shotcrete (gunite), and wet-mix shotcrete. Often used for swimming pools.

Slump A measure of the consistency of concrete relative to the amount it falls when a slump cone filled with concrete is lifted vertically.  The slump cone is then placed beside the specimen of concrete and the number of inches from the top of the cone to the top of the specimen of concrete is the slump. (see ASTM C143).

Slump Cone A metal mold in the form of a truncated cone with a top diameter of 4”, a bottom diameter of 8”, and a height of 12”, used to fabricate the specimen for a slump test. The greater the slump, the wetter (and weaker) the concrete usually is. Typically, you want the lowest slump allowable for your work.

Slurry A mixture of water and finely divided materials, such as Portland cement, slag, or soil in suspension. 

Spall A fragment, usually of flaky shape, a deformity of the finished surface.

Stucco A Portland cement mortar material that can be applied to the surface of any building or structure to form a hard and durable covering for the exterior wails or other exterior surfaces

Superplasticizer Concrete admixture that makes wet concrete extremely fluid without additional water. These agents perform the same function as a plasticizer, but are composed of different materials