This glossary is built for buyers, not engineers. If you are reading a concrete bid and keep seeing terms that are never explained, this page is here to help.
Base
A prepared layer directly under the slab that helps provide support and a workable surface for construction.
Bleed water
Water that rises to the surface of fresh concrete after placement.
Broom finish
A textured finish made by dragging a broom across the concrete surface. Common where slip resistance is important.
Chairs
Supports used to help keep reinforcement in the intended position before and during the pour.
Compaction
The process of densifying soil or fill so it provides more stable and uniform support.
Compressive strength
The ability of hardened concrete to resist crushing pressure. Usually described in PSI.
Control joint
A planned weakened line or saw cut intended to encourage cracking to occur in a more controlled location.
Curing
The process of helping concrete maintain appropriate moisture and temperature conditions so it can develop its intended properties.
Dobies
Small concrete supports sometimes used to support reinforcement.
Finish
The final surface treatment of the slab, such as hard-trowel or broom finish.
Footing
A widened or thickened portion of concrete that transfers loads into the ground.
Hard-trowel finish
A smooth, dense finish often used for interior slabs or shop floors, depending on the application.
Isolation joint
A joint that allows movement between the slab and another element such as a wall, column, or footing.
Joint
A planned separation, cut, or detail intended to manage movement, cracking, or construction sequence.
Monolithic pour
A pour where slab and footing elements are placed together as part of one integrated placement, depending on design and layout.
PSI
Pounds per square inch. In concrete work, this typically refers to compressive strength.
Rebar
Steel reinforcing bars used in concrete.
Reinforcement
Steel or other reinforcing materials placed in concrete to help improve performance under stress and help control crack behavior.
Saw cut
A cut made in hardened concrete to create a control joint.
Slab-on-grade
A concrete slab poured on prepared ground.
Subbase
A granular layer below the slab support system, depending on the assembly and terminology used on the project.
Subgrade
The soil or prepared earth supporting the slab system.
Thickened edge
A deeper section along the edge of a slab used to provide additional support.
Tolerance
The acceptable variation from a specified dimension or condition.
Vapor barrier / vapor retarder
A sheet membrane placed under many slabs to reduce moisture movement from the ground into the slab and building.
Welded wire reinforcement
A grid of steel wire used in concrete, often called wire mesh.
Workability
How easy fresh concrete is to place, consolidate, and finish.
Terms buyers should watch most carefully in bids
If you are comparing bids, pay special attention to these terms because they affect cost and performance quickly:
- slab thickness
- footing size
- PSI
- reinforcement
- vapor barrier
- compaction
- finish
- joints
- curing
- exclusions
Read next
Concrete Specs Explained
The full guide to slabs, footings, reinforcement, and what actually matters in a bid.
How to Compare Concrete Bids
A line-by-line method for comparing concrete bids without getting burned.
Verify Before the Pour
Step-by-step guide to checking the work before concrete covers it forever.
Pre-Pour Inspection Checklist
A printable checklist to take to the jobsite.
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