Concrete terms, defined
Plain definitions of the concrete words that come up on estimates, inspections and supplier calls, written for concrete contractors. Each term says where it matters on the job and links the Koira calculator, cost guide or template that goes with it.
A
ConcreteAdmixtureAn admixture is a chemical added to concrete to change how it behaves: speeding or slowing set, entraining air for freeze thaw resistance, or making it flow without extra water.ConcreteAggregateAggregate is the sand, gravel or crushed stone mixed into concrete and used as base under slabs and pavers.Shared with CarpentryAnchor boltAn anchor bolt is a bolt set in concrete, usually as it is poured, that ties the sill plate or a post base to the foundation.
B
ConcreteBagged concrete mixBagged concrete mix is premixed cement, sand and gravel sold in bags, mixed with water on site for small pours like post holes and pads.ConcreteBase courseThe base course is the layer of compacted gravel or crushed stone under a slab, patio or pavers that spreads loads and drains water.ConcreteBroom finishA broom finish is made by dragging a broom across fresh concrete to leave fine ridges for traction.ConcreteBull floatA bull float is a wide, flat tool on a long handle pushed across fresh concrete after screeding to level ridges and bring cream to the surface.
C
ConcreteCold jointA cold joint forms when fresh concrete is placed against concrete that has already started to set, so the two do not bond as one.Shared with LandscapingCompactionCompaction is pressing soil or gravel down with a plate compactor or roller so it is dense and will not settle under a slab, patio or wall.Shared with Masonry and HardscapeConcrete blockConcrete block, or CMU, is the hollow concrete masonry unit used for foundations, retaining walls and commercial walls.ConcreteConcrete curingCuring is keeping new concrete moist and at a reasonable temperature while it gains strength, with water, covers or a curing compound.ConcreteConcrete PSIConcrete PSI is the mix's compressive strength, how much load it can carry per square inch once cured, used to order the right mix.ConcreteConcrete sealerConcrete sealer is a penetrating or film forming coating that protects concrete from water, salt and stains.ConcreteControl jointA control joint is a groove tooled or sawn into a slab so that when concrete shrinks and cracks, it cracks along the joint instead of randomly.Shared with Masonry and HardscapeCrack fillingCrack filling is cleaning out cracks in asphalt or concrete and filling them with a flexible sealant to keep water out.Shared with TileCrack isolation membraneA crack isolation membrane is a sheet or liquid layer over a concrete slab that keeps small cracks in the slab from telegraphing up through the tile.Shared with CarpentryCripple wallA cripple wall is a short framed wall between the top of the foundation and the first floor, enclosing a crawl space.ConcreteCubic yardA cubic yard is the volume unit concrete, mulch, soil and gravel are ordered in, and the unit junk haulers often price by.
E
Shared with WaterproofingEfflorescenceEfflorescence is the white, powdery salt deposit left on concrete, brick or block when water moves through it and evaporates at the surface.ConcreteExpansion jointAn expansion joint is a full depth gap filled with a compressible material that lets concrete or masonry sections move without pushing on each other.
F
Shared with LandscapingFill dirtFill dirt is subsoil with little organic matter used to raise grade or fill holes, because it compacts and does not rot away.ConcreteFlatworkFlatwork is horizontal concrete work: driveways, sidewalks, patios, garage floors and slabs.ConcreteFootingA footing is the wide concrete base at the bottom of a foundation wall, column or post that spreads the load onto the soil.ConcreteForm releaseForm release is an oil or chemical coating sprayed on forms so concrete does not stick to them when they are stripped.ConcreteFormworkFormwork is the temporary mold of boards, steel or plastic that holds fresh concrete in shape until it sets.ConcreteFrost lineThe frost line is how deep the ground freezes in a given area.
I
Shared with General ContractorImpervious surfaceAn impervious surface is one water cannot soak through, such as roofs, driveways, patios and most pavement.ConcreteIsolation jointAn isolation joint separates a slab from things that move differently, such as walls, columns, steps and drains, so the slab can move on its own.
S
ConcreteScreedTo screed is to strike fresh concrete level by dragging a straight board or power screed across the forms.Shared with FlooringSelf-leveling compoundSelf-leveling compound is a pourable cement based mix that flows out to fill low spots and make a flat floor for tile or flooring.Shared with CarpentrySill plateThe sill plate is the board laid flat on top of the foundation wall, bolted down, that the floor framing or wall sits on.ConcreteSlumpSlump is how much fresh concrete sags when a cone of it is lifted away in a slump test.ConcreteStamped concreteStamped concrete is fresh concrete pressed with textured mats to look like stone, brick or tile, usually colored and sealed.Shared with General ContractorStructural engineerA structural engineer is a licensed professional who designs or checks the parts of a building that carry loads, and stamps drawings for the permit.
More for concrete contractors: free concrete tools, templates and guides and how the trade runs on Koira. Or browse the whole glossary.