Resource
Concrete glossary
Plain-language definitions for the terms that show up in a concrete quote: mix specifications, base preparation, finishes, failure modes, and the Cleveland right-of-way vocabulary.
- Air entrainment
- An admixture that creates millions of microscopic air bubbles distributed through concrete. Those voids act as expansion chambers, giving freezing water somewhere to go instead of fracturing the cement paste. For exterior flatwork in a freeze-thaw climate like Cleveland it is the baseline specification, typically five to seven percent air content, and concrete poured outdoors here without it will deteriorate.
- Freeze-thaw cycling
- The repeated freezing and thawing of water absorbed into porous concrete. Water expands roughly nine percent when it freezes, and trapped inside the slab that expansion generates enough pressure to fracture the paste. Northeast Ohio experiences dozens of these cycles each winter, most heavily during shoulder seasons when temperatures swing across freezing daily.
- Scaling
- The loss of the surface layer of cement paste from a slab, leaving a rough, pitted finish with exposed aggregate. The signature concrete failure in Northeast Ohio, caused by freeze-thaw action accelerated by road salt. Usually traces back to inadequate air entrainment, too much water in the mix, finishing errors, poor curing, or deicer applied during the first winter.
- Spalling
- Larger pieces of concrete breaking away from a slab, often over reinforcement or at edges and joints. More severe than scaling and frequently a sign of water reaching embedded steel, which then corrodes and expands, pushing the concrete off.
- Pop-out
- A small conical crater in a concrete surface, caused by an individual aggregate particle near the surface absorbing water and fracturing during a freeze. Cosmetic rather than structural in most cases, though widespread pop-outs suggest a problem with the aggregate used.
- Crazing
- A network of very fine, shallow surface cracks resembling cracked glaze on pottery. Usually caused by rapid surface drying during finishing. Cosmetic and not structural, though it can make a surface slightly more prone to holding dirt.
- Compressive strength (psi)
- The load a concrete mix can carry, measured in pounds per square inch after a standard cure period. Exterior flatwork in the Cleveland climate warrants 4,000 psi or higher. Higher strength generally reflects a lower water-to-cement ratio, which means fewer and finer pores for water to occupy.
- Water-to-cement ratio
- The proportion of water to cement in a concrete mix, and the single biggest determinant of strength and durability. Adding water at the truck to make concrete easier to place is a common shortcut that directly weakens the surface layer, which is exactly where scaling begins.
- Subgrade
- The native soil beneath a concrete slab and its base. Across much of Cuyahoga County this is glacial till and lake-plain clay: dense, slow-draining, frost-susceptible, and prone to heaving when saturated and frozen. Soft or organic subgrade material is removed rather than covered during proper site preparation.
- Aggregate base
- A layer of compacted crushed stone placed between the subgrade and the concrete slab. It drains water away from the underside of the slab, distributes load across the soil, and provides a uniform bearing surface. On Cleveland clay it is the most important and least visible part of any flatwork project.
- Compaction
- Mechanically densifying soil or aggregate with a plate compactor or roller before pouring. Stone dumped and raked flat is not a compacted base, and the difference is invisible on pour day but decisive within a few years. Deeper base layers are compacted in lifts rather than all at once.
- Frost heave
- The upward movement of ground caused by water in the soil freezing and expanding. Clay soils are especially susceptible because they retain water. Because saturation is never uniform across a driveway, heave lifts a slab unevenly, which is what cracks it. A draining aggregate base is the primary defense.
- Control joint
- A groove cut or tooled into a slab at planned spacing, creating a deliberate weak line so the concrete cracks there rather than randomly across the surface. All concrete moves and cracks; control joints decide where. Spacing depends on slab thickness and geometry.
- Expansion joint
- A gap filled with compressible material where a slab meets a fixed structure such as a foundation, a garage wall, or an adjacent slab. It allows independent thermal movement so the slab does not transfer pressure into the structure or crack against it.
- Flatwork
- The industry term for horizontal concrete: driveways, patios, sidewalks, garage floors, and slabs. Distinguished from vertical or structural concrete such as walls and footings, which involves different forming, reinforcement, and finishing.
- Apron
- The section of driveway between the sidewalk line and the street. In Cleveland it sits in the public right-of-way, so work on it requires a municipal permit, and it takes the heaviest salt and vehicle loading of any concrete on a property, which is why it usually fails first.
- Tree lawn
- The strip of grass between the sidewalk and the curb, called the tree lawn in Cleveland and the devil strip or verge elsewhere. It sits in the public right-of-way and the street trees planted in it are generally city trees, which limits what can be done to their roots when they lift adjacent sidewalk slabs.
- Right-of-way
- The strip of public land running along a street, which in a typical Cleveland residential setup covers the tree lawn, the public sidewalk, and the driveway apron. Work in the right-of-way requires a municipal permit and inspection, even though maintaining the sidewalk fronting a property is the adjacent owner responsibility.
- Point-of-sale inspection
- A municipal inspection required when a residential property changes hands, used by several Cleveland-area suburbs including Cleveland Heights, Shaker Heights, Lakewood, Euclid, and Garfield Heights. Violations must be corrected or escrowed at closing. Heaved sidewalks, deteriorated aprons, and crumbling steps are commonly cited.
- Curing
- Maintaining moisture in fresh concrete so hydration, the chemical reaction that develops strength, can continue. Concrete does not dry to gain strength, it reacts with water. Curing compounds, wet coverings, or plastic sheeting hold that moisture in, producing a denser and more durable surface layer.
- Bleed water
- Water that rises to the surface of fresh concrete after placement as heavier solids settle. Finishing a slab while bleed water is still present works excess water back into the surface, creating a weak skin that scales early. Crews wait for it to evaporate before final finishing.
- Broom finish
- A slip-resistant surface texture created by dragging a stiff broom across concrete before it sets. The standard finish for driveways, walks, and patios in a climate with snow and ice, because it provides traction when wet.
- Exposed aggregate
- A finish where the surface paste is washed or chemically retarded back to reveal the decorative stone within the concrete. Naturally slip-resistant, visually rich, and it ages more gracefully than printed finishes because there is no surface pattern to fade.
- Stamped concrete
- Concrete patterned with textured mats pressed into the surface while it is still plastic, imitating flagstone, slate, brick, or cobblestone. Combined with integral color or a color hardener plus a release agent. Requires sealing on a regular schedule in this climate to protect the color and surface.
- Color hardener
- A pigmented powder broadcast onto the surface of fresh concrete and worked in, producing a colored and denser wearing surface. An alternative to integral color, which pigments the entire batch. Color hardener gives stronger color at the surface, where it is seen.
- Release agent
- A powder or liquid applied before stamping so the texturing mats do not bond to the fresh concrete. Powdered releases also leave secondary shading in the pattern recesses, giving stamped work its depth and variation.
- Penetrating sealer
- A sealer that soaks into concrete rather than forming a surface film, reducing water and chloride absorption. Because water absorption drives freeze-thaw and salt damage, sealing is one of the most cost-effective maintenance steps available in this climate. Typically reapplied every few years.
- Slabjacking
- Lifting a settled concrete slab back to grade by drilling small holes and pumping filler material underneath. Also called mudjacking. Well suited to the uneven settling common on Cleveland clay soils and far cheaper than removal and replacement, though it does not help a slab that is broken up or actively heaving.
- Resurfacing overlay
- A thin cementitious layer bonded over an existing slab to restore a clean surface and cover scaling. Requires a structurally sound slab underneath, since an overlay applied over a cracking or moving slab cracks with it. Can be stamped or colored, making it an option for updating appearance as well as condition.
- Wire mesh and rebar
- Steel reinforcement placed within a slab to hold cracks tight and add tensile capacity. Welded wire mesh is common in residential flatwork; rebar is used where loads are heavier. Both need to sit at the correct height within the slab rather than lying on the base, which is why chairs or supports are used.
- Fiber reinforcement
- Synthetic or steel fibers mixed throughout the concrete rather than placed as a grid. Effective at controlling early shrinkage cracking and simpler to place than mesh, though it does not replace rebar where structural capacity is required.
- Vapor barrier
- A plastic sheet placed under a slab to stop ground moisture wicking up through the concrete. Worth including for heated or finished garage floors and anywhere a coating will be applied later, since coatings fail when moisture pushes through from below.
- Deicer
- A chemical applied to melt ice. Rock salt (sodium chloride) is the common and cheap one and the primary driver of concrete scaling in this region. Calcium magnesium acetate is the gentlest chemical option. Products containing ammonium sulfate or ammonium nitrate actively attack concrete and should be avoided entirely. Sand provides traction with no chemical effect at all.
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