Concrete Terms Glossary
Concrete Terms Glossary
A plain-English dictionary of concrete terminology — materials, finishes, installation, tools, repair, and estimating — for Denver homeowners planning a project.
Whether you’re getting your first quote or comparing bids from Denver concrete contractors, it helps to know the vocabulary. This glossary explains the terms you’ll hear during a concrete estimate, installation, or repair — from the materials in the mix to the finish on the surface. Use the categories on the left to jump to a section, or search the page for a specific word (Ctrl+F / Cmd+F).
Materials & Mixes
Admixture — A chemical additive mixed into concrete to change its properties, such as speeding up curing time, improving workability, or increasing resistance to freeze-thaw cycles.
Aggregate — The gravel, crushed stone, or sand mixed with cement and water to form concrete. Aggregate makes up roughly 60-75% of a concrete mix and affects strength, texture, and appearance.
Air-Entrained Concrete — Concrete mixed with microscopic air bubbles that give water room to expand when it freezes. This is essential for any outdoor concrete in Colorado, where freeze-thaw cycles are frequent and can crack ordinary concrete over time.
Efflorescence — The white, chalky residue that sometimes appears on a concrete surface as water evaporates and leaves mineral salts behind. It’s cosmetic, not structural, and can usually be cleaned off.
Fiber Reinforcement — Synthetic or steel fibers blended directly into the concrete mix to reduce cracking, often used alongside or instead of wire mesh in driveways and patios.
Fly Ash — A byproduct of coal combustion used as a partial substitute for cement in the mix. It improves long-term strength and workability and is considered a more sustainable material choice.
Portland Cement — The binding ingredient in concrete, made from limestone and clay. When mixed with water, it triggers the chemical reaction (“hydration”) that hardens concrete. Despite the name, it contains no rock from Portland — it’s named for its resemblance to Portland stone.
PSI (Pounds per Square Inch) — The standard measurement of concrete’s compressive strength. Residential driveways typically use 3,500-4,000 PSI mixes; Colorado’s freeze-thaw climate often calls for the higher end of that range.
Ready-Mix Concrete — Concrete batched at a plant and delivered to the job site by truck, already mixed to the specified strength — the standard method for most residential driveway and patio pours.
Sealant / Sealer — A protective coating applied to cured concrete to repel water, resist stains, and reduce surface wear. Sealing is recommended every 2-3 years for driveways exposed to Denver winters and de-icing salt.
Slump — A measurement of how wet or stiff a concrete mix is before it’s poured, tested by filling a cone-shaped mold and measuring how much the mix settles once the cone is removed. Slump affects workability and finish quality.
Vapor Barrier — A plastic sheet placed under a concrete slab before the pour to block ground moisture from migrating up through the concrete — important for garage floors and any slab that will have flooring installed over it.
Water-Cement Ratio — The proportion of water to cement in a mix. A lower ratio generally produces stronger, more durable concrete, while too much water weakens the finished slab.
Wire Mesh (Welded Wire Fabric) — A grid of steel wire embedded in a concrete slab for reinforcement, helping control cracking as the concrete cures and settles.
Finishes & Techniques
Acid Staining — A decorative technique using reactive acid-based stains to create mottled, variegated color in a concrete surface — popular for patios that want a stone-like or marbled look.
Broom Finish — A textured, slip-resistant surface created by dragging a broom across freshly floated concrete. It’s the standard finish for driveways and walkways because it improves traction in rain, ice, and snow.
Bull Float — A large, flat tool used to smooth and level freshly poured concrete right after it’s placed, removing high spots and pushing larger aggregate below the surface before finer finishing begins.
Concrete Overlay — A thin layer of specialized concrete applied over an existing slab to refresh its appearance or add a decorative finish, without the cost of a full tear-out and replacement.
Control Joint (Tooled Joint) — A groove cut or tooled into a slab in a planned pattern to control where cracks form as the concrete shrinks during curing. Every properly poured driveway or patio should have control joints spaced according to the slab’s thickness.
Edging — The rounding of a slab’s edges with a hand tool before the concrete fully hardens, preventing sharp, chip-prone corners.
Exposed Aggregate — A finish where the top layer of cement paste is washed or brushed away after the pour, revealing the decorative stone aggregate underneath for a textured, natural look.
Expansion Joint — A flexible joint (often filled with a compressible material) placed where a concrete slab meets another structure, like a garage foundation or existing sidewalk, allowing the slab to expand and contract independently without cracking.
Float Finish — A smooth, even surface created by passing a float (hand tool or machine) over the concrete after bull floating — usually the step before a broom or trowel finish is applied.
Micro-Topping — An ultra-thin decorative overlay, often only a few millimeters thick, used to resurface interior or covered concrete surfaces with a smooth, modern finish.
Polished Concrete — Concrete mechanically ground and polished to a smooth, glossy finish, most common for garage floors and interior spaces that want a durable, low-maintenance surface.
Salt Finish — A textured, pitted finish created by pressing rock salt into fresh concrete, then washing it out once the concrete cures — a decorative option for patios and pool decks.
Screed — The process (or the tool) used to strike off excess concrete to the correct level immediately after it’s poured into forms, using a straight board or power screed dragged across the top of the forms.
Stamped Concrete — Concrete imprinted with textured stamps while still workable, replicating the look of stone, brick, slate, or wood at a fraction of the material cost. See our stamped concrete page for pattern and color options.
Trowel Finish — A dense, smooth surface created by passing a hand or power trowel over concrete after floating — common for garage floors and indoor slabs, but too slick for driveways or walkways without additional texture.
Structural & Installation
Compaction — Mechanically packing down the soil or gravel base before pouring concrete, using a plate compactor or roller, to prevent future settling and cracking of the slab above it.
Crown (Sidewalk Crown) — A slight, intentional rise in the center of a slab that sheds water toward the edges rather than letting it pool on the surface.
Footing — A wider, reinforced concrete base poured below the frost line that supports a foundation wall or structural slab, distributing weight and preventing shifting.
Formwork — The temporary wood or metal frames used to hold wet concrete in its intended shape until it cures enough to hold that shape on its own.
Frost Heave — The upward movement of soil (and anything poured on top of it) caused by freezing groundwater expanding beneath the surface — a common cause of cracked or uneven concrete in Colorado if the subgrade isn’t properly prepared.
Grading — Shaping and sloping the ground before a pour so that water drains away from structures instead of toward them — one of the most important steps for a driveway or patio that will last.
Pitch / Slope — The angle built into a slab to direct water runoff, typically expressed as inches of drop per foot of run (e.g., a 1/4-inch-per-foot slope away from a garage or house).
Rebar (Reinforcing Bar) — Steel rods embedded in concrete to add tensile strength, since concrete is strong under compression but weak under tension. Rebar is standard in driveways, footings, and any slab that will bear significant weight.
Slab-on-Grade — A concrete slab poured directly on a prepared and compacted ground surface, without a basement or crawlspace beneath it — the typical foundation type for driveways, patios, and garage floors.
Subbase — The layer of compacted gravel or crushed stone placed between the native soil (subgrade) and the concrete slab, providing drainage and a stable, level surface to pour on.
Subgrade — The natural ground beneath a concrete installation, prepared by excavating, grading, and compacting before the subbase and concrete are added.
Tools & Equipment
Concrete Mixer — Equipment that combines cement, aggregate, and water into a workable mix, ranging from small portable mixers for repair work to full ready-mix delivery trucks for driveway-sized pours.
Concrete Saw — A gas, electric, or walk-behind saw with a diamond blade used to cut clean control joints or to remove sections of an existing slab during repairs or replacement.
Concrete Vibrator — A tool inserted into freshly poured concrete to eliminate air pockets and ensure the mix settles fully into forms and around rebar, producing a stronger, more uniform slab.
Edger — A hand tool with a curved blade used to round and smooth the edges of a slab and the joints along forms.
Groover — A hand tool used to cut control joints into concrete while it’s still workable, guiding where the slab will crack as it cures.
Power Trowel — A ride-on or walk-behind machine with rotating blades that finishes large concrete surfaces to a smooth, dense finish far faster than hand troweling — typically used on garage floors and commercial slabs.
Screed Board — A straight, rigid board (or powered screed) dragged across wet concrete resting on the tops of the forms, striking off excess material to bring the surface to the correct level.
Maintenance & Repair
Crack Filler / Epoxy Injection — Materials used to seal cracks in existing concrete, ranging from flexible caulk-like fillers for hairline cracks to structural epoxy injections for larger, load-bearing cracks.
Discoloration — Uneven coloring or staining on a concrete surface, often caused by de-icing salts, oil, rust from rebar, or inconsistent curing — sometimes correctable with cleaning, staining, or resurfacing.
Freeze-Thaw Damage — Deterioration caused by water repeatedly seeping into concrete, freezing, expanding, and cracking the surface — one of the most common causes of driveway damage in Denver’s climate, especially on older or non-air-entrained concrete.
Hairline Crack — A thin, shallow crack usually caused by normal shrinkage as concrete cures. Hairline cracks are typically cosmetic and don’t affect the slab’s structural integrity.
Pitting — Small holes or craters on a concrete surface, often from de-icing chemicals, freeze-thaw cycling, or trapped air that wasn’t properly finished out at the time of the pour.
Resurfacing — Applying a new layer of concrete or a bonding overlay to an existing slab to repair surface damage and restore appearance, without removing and re-pouring the entire slab.
Scaling — The flaking or peeling away of a concrete surface’s top layer, commonly caused by freeze-thaw cycles combined with de-icing salts.
Spalling — Chipping, flaking, or pitting of a concrete surface, often exposing the aggregate beneath — a sign of moisture damage, poor original finishing, or reinforcing steel corroding beneath the surface.
Structural Crack — A wider or shifting crack that may indicate settling, foundation movement, or inadequate reinforcement — unlike hairline cracks, these should be evaluated by a contractor.
Costs & Estimating
Change Order — A written revision to the original project scope or price, used when a homeowner requests additional work or unforeseen site conditions require adjustments after the estimate is approved.
Cubic Yard — The standard unit for ordering ready-mix concrete, equal to 27 cubic feet. Contractors calculate cubic yards from a project’s square footage and slab thickness to determine how much concrete to order.
Demolition & Haul-Away — The removal of an existing slab and disposal of the debris, typically priced separately from the new concrete installation.
Linear Foot Pricing — A pricing method based on length rather than area, common for curbing, sidewalks of a fixed width, or edging work.
Permit — Approval required from the local municipality before certain concrete work begins, particularly for new driveways, structural slabs, or work that affects a public right-of-way. Not sure if a permit applies to your project? Ask our team.
Site Prep — All the work that happens before concrete is poured: demolition, excavation, grading, and base compaction. Site conditions (slope, access, existing landscaping) directly affect estimate pricing.
Square Footage Estimate — The most common way concrete projects are priced — length times width of the area to be poured — though price per square foot varies with slab thickness, finish, and site complexity.
Cure Time vs. Dry Time — Concrete is dry to the touch within a day or two, but curing — the chemical process that builds strength — continues for about 28 days. Most contractors recommend keeping vehicles off a new driveway for at least 7 days and avoiding heavy loads until the full cure.
Turnaround Time — The estimated time from the start of a project to completion, including site prep, forming, pouring, finishing, and curing before the area is ready for use.
Workmanship Warranty — A guarantee from the contractor covering defects in labor and installation (separate from any manufacturer warranty on materials) — always worth asking about before signing a contract.