Sidewalk repair glossary

How to use this glossary

A repair bid or an assessment report uses a small set of trade words, and each one points to a different repair. This page defines them in plain English. Definitions marked ACI follow the American Concrete Institute's published terminology. Definitions marked FHWA follow the Federal Highway Administration's 2013 guide to maintaining sidewalks and paths. A definition with no mark is this site's plain description.

None of these words is a measurement of your walkway. If a bid uses a term in a way that does not match its definition here, ask the contractor what they mean by it.

Words for movement

Change in level

A step between two surfaces that should be even. FHWA lists it as one of several names for the same condition, along with vertical displacement, vertical uplift and faulting.

Faulting

ACI defines faulting as differential displacement of a slab along a joint or crack. In plain terms, one side sits higher than the other.

Heaving

A panel that has risen. FHWA says heaving most often shows up at the joints, because that is where a walkway is jointed. Its listed causes include expansive soil, frost and tree roots.

Settlement

A panel that has dropped below its neighbors. FHWA notes that people commonly call this sagging. Its listed causes include soil that shrinks as it dries and a subgrade that was not compacted evenly.

Cross slope and running slope

Cross slope is the tilt across the width of a path, at a right angle to the direction of travel. Running slope is the slope along the direction of travel. The U.S. Access Board's standards define the two terms this way.

Trip hazard

A common phrase in bids with no single published definition in the sources opened for this page. When a bid counts "trip hazards," ask what height it counts from and why.

Parts of a walkway

Panel or slab

One section of concrete between joints. ACI calls concrete cast directly on the ground a slab-on-ground, also known as a slab-on-grade.

Joint

A planned line between panels. FHWA explains why joints exist: any length of concrete will eventually crack, so the builder places joints to direct the cracking.

Contraction joint or control joint

ACI defines it as a groove that is formed, sawed or tooled into concrete to create a weakened plane, so that cracking happens there. These are the shallow lines that divide a walkway into squares.

Expansion joint and isolation joint

An expansion joint is a separation between slabs, filled with a compressible material, that lets them grow and shrink. An isolation joint is a separation that lets the concrete on each side move independently in any direction. Both descriptions follow ACI.

Sawed joint

ACI: a joint cut in hardened concrete, generally not to the full depth. It is a different thing from horizontal saw cutting, which is a repair.

Joint filler and joint sealant

Filler is the compressible material in a joint that keeps debris out and supports the sealant. Sealant is the material on top that keeps out water and grit. Both follow ACI.

Subgrade, subbase and base

The subgrade is the soil prepared and compacted to carry the walkway. A base course is a layer of selected material placed on it to spread load and drain water. A subbase, where there is one, sits between the two. All three follow ACI. When a report blames "the base," it means what is under the slab, not the concrete.

Broom finish

ACI: the texture left by stroking a broom over fresh concrete. It is the fine ridged surface on many walkways, and it is why a ground or cut repair looks different.

Curing

ACI defines curing as keeping fresh concrete at the right moisture and temperature so it can gain its strength. It is one reason a newly poured panel is kept closed for a time.

Words for damage

Crack

ACI: a complete or incomplete separation of concrete into two or more parts. FHWA describes a longitudinal crack as one running along the length of the walkway, and a transverse crack as one running across its width.

Craze cracks and map cracking

Craze cracks are fine, random cracks in the surface. Map cracking is a pattern of intersecting cracks that go below the surface. Both follow ACI.

Spall

ACI: a fragment, usually flake-shaped, that has broken off a larger mass. A spalled joint has lost pieces from its edge.

Scaling

ACI: local flaking or peeling of the surface layer of hardened concrete.

Popout

ACI: a small piece that breaks away from the surface and leaves a shallow, usually cone-shaped hole.

Raveling

ACI: the surface wearing away as stones are dislodged from it.

Words for repairs

Grinding

ACI defines grinding as deliberately removing surface material to create a profile. On a walkway it means wearing down the lip of a raised panel. See the grinding page.

Horizontal saw cutting

Removing the raised lip with a saw that cuts level with the walkway. FHWA says it leaves a very smooth face with the stones in the concrete exposed. This site's grinding page also uses the word shaving for it, which is not a term from the guide.

Wedging

FHWA: placing an asphalt or concrete filler ahead of a raised edge to form a small ramp. The guide rates it as a temporary repair.

Slab jacking, mudjacking and foam lifting

ACI defines slab-jacking as raising slabs or filling the voids under them by injecting material under pressure, and lists mudjacking as another word for it. Foam lifting is the same repair done with expanding polyurethane. The lifting methods guide compares the materials.

Slab stabilization or undersealing

Filling a void to restore support without raising the slab. A federally sponsored pavement guide draws that line between stabilization and jacking.

Void

An empty space under a slab where the soil or base has washed out, shrunk or settled.

Grout

ACI: a mixture of cementitious material and water, with or without aggregate. In mudjacking it is the material pumped under the slab.

Remove and replace

Taking out whole panels and pouring new ones. FHWA describes it as the entire removal and replacement of sidewalk sections, and adds that the new panel has a shortened life if the cause of the failure is not dealt with. See replacement.

Words that deserve a question

Some words in a bid are promises, not descriptions. "Compliant" asks which standard, measured by whom. "Permanent" asks what happens if the panel moves again. "Warranty" asks what it covers and for how long. A careful contractor will answer all three in writing.

Next steps

Use the walkway inspection checklist to record what you see in these terms. The three-method comparison matches each kind of damage to a repair, and assessment planning covers a property with many locations. Then ask about your project.