28 terms defined
Concrete Glossary
Concrete estimates are full of jargon, and it is occasionally used to move past questions rather than answer them. Here is every term you are likely to encounter, in plain English, with the Oklahoma context that makes it matter.
Admixture
Chemicals added to a concrete mix to change how it behaves — accelerators for cold weather, retarders to slow setting in Oklahoma summer heat, plasticizers to improve workability without adding water. Admixtures are how a good crew manages temperature instead of watering down the truck.
Aggregate
The sand, gravel and crushed stone that make up most of concrete by volume. Cement paste binds it; the aggregate does the structural work and controls shrinkage.
Air entrainment
Microscopic air bubbles deliberately introduced into a mix. They give freezing water somewhere to expand into, which is why air-entrained concrete survives Oklahoma freeze-thaw cycling far better than concrete without it.
Broom finish
The standard exterior texture, produced by dragging a broom across the surface before it sets. Provides slip resistance and is the baseline finish most Oklahoma bids assume unless something else is specified.
Chairs
Small supports that hold rebar or mesh in the middle third of a slab during the pour. Steel resting on the subgrade contributes almost nothing structurally, so chairs are the difference between reinforcement that works and reinforcement that is merely present.
Compaction
Mechanically densifying the subgrade before pouring. On Oklahoma clay this is the single most important step in the whole job, and the one you can never inspect afterward.
Control joint
A groove cut or tooled into a slab so it cracks in a straight line beneath the joint rather than randomly across the surface. Cut within hours of the pour, spaced at roughly 24-30 times the slab thickness — about 10 feet for a 4-inch slab.
Crazing
A shallow web of fine surface hairlines, usually from the surface drying faster than the mass beneath. Cosmetic, not structural.
Cure
The chemical reaction between cement and water that develops strength. Not the same as drying. Foot traffic after 24-48 hours, vehicles after 7 days, full design strength at about 28 days.
Curing blanket
Insulated covering that holds heat and moisture in a fresh slab. Used for cold-weather pours; the reason a winter pour is possible at all, though usually still worth avoiding.
Exposed aggregate
A finish where the surface paste is washed away to reveal the stone beneath. Adds $2-$5 per square foot, gives excellent slip resistance, and ages more gracefully than stamping because there is no surface color to wear through.
Expansion joint
A full-depth separation, usually with compressible filler, between a slab and an adjacent structure — typically where a patio meets the house. Lets the two move independently through seasonal cycles instead of transmitting movement into the wall.
Expansive soil
Soil that changes volume with moisture content. Oklahoma Permian red-bed clays, rich in montmorillonite and smectite, are among the most expansive in the country, with plasticity index readings across the Tulsa metro commonly 30-55.
Flatwork
The trade term for horizontal concrete — driveways, patios, sidewalks, slabs. Distinct from structural or vertical concrete work.
Freeze-thaw cycling
Water entering concrete, freezing and expanding roughly 9%, then thawing. Each cycle levers existing cracks wider. The reason sealing every two to three years matters in Oklahoma.
Integral color
Pigment mixed through the whole batch rather than applied to the surface, so the color goes all the way through and wear does not expose grey concrete underneath. Adds $0.75-$1.50 per square foot.
Mudjacking
Pumping a cement slurry beneath a settled slab to lift it. Largely superseded by polyurethane foam, which is lighter and cures in minutes rather than adding weight to already-weak soil.
PSI
Pounds per square inch — the compressive strength a mix is designed to reach at 28 days. Residential Oklahoma flatwork is typically 3,000-4,000 PSI. Adding water on site to ease placement reduces the strength you actually get.
Plastic shrinkage cracking
Fine cracks appearing within hours of a pour, caused by the surface drying faster than the slab beneath. The characteristic risk of an Oklahoma summer pour, and the reason cooling measures exist.
Polyurethane foam lifting
Injecting expanding foam through dime-sized holes to fill voids and raise a settled slab. Faster, cheaper and less disruptive than replacement — appropriate where the concrete is sound but has dropped.
Rebar
Steel reinforcing bar. Placed in a grid within the slab to hold cracked sections together and resist tensile forces concrete cannot. Adds $0.40-$0.75 per square foot with wire mesh.
Release agent
Powder or liquid applied before stamping to stop mats sticking, which also deposits a secondary color that gives depth. Skipping or rushing it is why some stamped work reads flat and obviously artificial.
Sealer
A surface treatment resisting water, salts and staining. In Oklahoma, resealing every two to three years meaningfully extends slab life, and decorative surfaces need it more than plain ones.
Slab-on-grade
Concrete poured directly on prepared soil with no crawl space or basement beneath. The dominant construction across Oklahoma, and the reason subgrade preparation matters so much here.
Spalling
Surface concrete flaking, chipping or popping off. Usually freeze-thaw damage or de-icing salt attack. Unlike a crack, this is the concrete itself deteriorating and generally means replacement rather than repair.
Stamped concrete
Pattern and texture pressed into a slab while still plastic, usually with color, to imitate stone, brick or slate. Adds $4-$8 per square foot. Entirely dependent on crew skill and impossible to correct after the slab sets.
Subgrade
The prepared ground a slab sits on. Compaction, moisture condition and drainage here determine whether a slab lasts 15 years or 40 — and it is completely invisible once the concrete is down.
Wire mesh
Welded steel grid used as reinforcement, common in residential flatwork. Adequate for standard 4-inch work when properly positioned in the middle of the slab; useless lying on the subgrade.