Methods & Repair Options
Concrete Grinding
Concrete grinding uses a grinder to shave down high spots or trip lips on a slab. It’s sometimes used with lifting when only a small height difference remains.
Concrete Levelling
Concrete levelling is another term for lifting a slab so its surface is even and safe to walk or drive on again. It focuses on correcting height differences that cause trip hazards or drainage issues.
Concrete Lifting
Concrete lifting is a repair method that raises sunken or uneven slabs back toward their original position without tearing them out. It’s typically done by injecting material under the slab to fill voids and push it up.
Concrete Raising
Concrete raising is a general term for bringing a settled slab back up instead of replacing it. It covers methods like mudjacking and polyurethane concrete lifting.
Concrete Replacement
Concrete replacement means tearing out the old slab and pouring new concrete. It’s usually chosen when the slab is badly broken, very thin, or structurally failed beyond repair.
Concrete Resurfacing
Concrete resurfacing adds a thin layer of new material over existing concrete to improve the surface. It can make slabs look better but does not fix underlying settlement or support problems.
Concrete Sealing
Concrete sealing applies a protective coating to the surface of the slab to help resist water, salt, stains, and freeze-thaw damage. It does not fix settlement but helps protect the concrete after repairs.
Epoxy Crack Injection
Epoxy crack injection fills cracks with a strong resin to bond the concrete back together. It’s often used on structural cracks in foundations and some slabs when strength is a concern.
Foam Jacking (Polyjacking)
Foam jacking uses expanding polyurethane foam injected under the slab to lift and stabilize it. The foam is lightweight, sets quickly, and allows for smaller drill holes than traditional mudjacking.
Mudjacking
Mudjacking is an older lifting technique that pumps a heavy slurry of water, soil, and cement under a sunken slab. It can work but requires larger holes and adds more weight to already weak soil.
Polyurethane Foam Injection
Polyurethane foam injection is a concrete lifting method where a two-part foam is injected through small holes under the slab. As the foam expands, it fills voids, compacts weak soil, and gently raises the concrete.
Polyurethane Concrete Levelling
Polyurethane concrete levelling is a concrete repair method that uses expanding polyurethane foam injected under a settled slab to bring it back to a level, even surface. The foam fills voids, compacts weak soil, and allows for precise height adjustments with very small drill holes and fast cure times.
Polyurethane Concrete Lifting
Polyurethane concrete lifting is a modern slabjacking technique where a two-part polyurethane foam is injected through small holes beneath sunken concrete to raise it toward its original position. As the foam expands, it fills gaps, stabilizes the base, and lifts the slab with controlled pressure, providing a long-lasting alternative to traditional mudjacking.
Polyurethane Concrete Raising
Polyurethane concrete raising is the process of lifting and stabilizing sunken or uneven concrete by injecting high‑density polyurethane foam beneath the slab. The foam expands to fill voids and support the concrete from below, restoring proper height while strengthening the underlying soil and reducing future settlement.
Slab Jacking
Slab jacking is the process of drilling holes through a slab and pumping material underneath to raise and support it. It solves problems like sunken driveways, sidewalks, and garage floors.
Soil Stabilization
Soil stabilization improves the strength and stiffness of the ground under a slab. When done with foam, it fills loose areas and helps the soil carry the weight of the concrete and traffic.
Underslab Insulation (via Polyurethane Injection)
Underslab insulation via polyurethane injection is a method where high-density polyurethane foam is injected beneath an existing concrete slab to add thermal insulation and support at the same time. The foam creates a continuous insulating layer that reduces heat loss through the slab while also filling voids and stabilizing the base, which helps improve comfort, energy efficiency, and long‑term slab performance.
Underpinning
Underpinning strengthens or deepens the support of a foundation or structural slab, often using piers or other deep supports. It’s a structural repair, not a standard slab lifting job.
Void Filling
Void filling means injecting material into empty spaces under concrete to restore support. It helps prevent further settlement, hollow sounds, and cracking.
Problems & Conditions
Concrete Heaving
Concrete heaving happens when a slab is pushed upward, often by expanding soil or frost. It can cause raised sections, jammed doors, and uneven joints.
Delamination
Delamination is when the top layer of concrete separates from the layer below. It often shows up as hollow-sounding areas or thin sheets of surface concrete breaking loose.
Differential Settlement
Differential settlement is when one part of a slab or structure settles more than another. This uneven movement creates cracks, trip edges, and gaps instead of everything moving evenly.
Freeze–Thaw Cycle
A freeze–thaw cycle is the repeated freezing and thawing of water in, under and around concrete. When water gets into pores or cracks, freezes, and expands, it can break down the concrete surface over time, leading to damage like scaling, spalling, and cracking.
Frost Heave
Frost heave occurs when moisture in the soil freezes, expands, and lifts the concrete above it. In cold climates, it’s a common cause of seasonal movement and uneven slabs.
Hairline Crack
A hairline crack is a very narrow crack, often just visible at the surface. Many hairline cracks are cosmetic, but they can still allow water and salts into the concrete.
Pitting
Pitting is small, shallow holes or craters in the surface of concrete. It can be caused by salt, chemicals, or surface wear over time.
Scaling
Scaling is a type of surface damage where thin layers of concrete peel or flake off. It typically starts at the surface and is common in freeze-thaw climates.
Settlement Cracking
Settlement cracking happens when the concrete or the soil under it moves downward after the slab is placed. These cracks often appear near low spots or along areas where the slab has dropped.
Shrinkage Cracking
Shrinkage cracking occurs as concrete dries and shrinks after placement. It often shows up as fine, random cracks that don’t indicate movement in the soil.
Slab Settlement
Slab settlement is when a concrete slab sinks or tilts because the soil under it has compressed, washed away, or wasn’t compacted properly. It commonly shows up as a step down, lip, or slope in the wrong direction.
Soil Erosion (under concrete)
Soil erosion under concrete is when water washes away the supporting soil from beneath a slab. This creates voids and eventually causes the slab to settle or break.
Spalling
Spalling is when pieces or flakes of concrete break off the surface, often exposing aggregate. It’s usually caused by freeze-thaw cycling, de-icing salts, or poor finishing.
Structural Crack
A structural crack is a crack that may affect the strength or stability of the concrete or what it’s supporting. These cracks are usually wider, deeper, or located under load-bearing walls or columns and should be assessed carefully.
Trip Hazard
A trip hazard is a height difference between slab sections or between concrete and another surface that can catch a foot. Often, a rise as small as 1/4–1/2 inch can be considered a trip hazard.
Void Under Concrete
A void under concrete is an empty space between the bottom of the slab and the soil or base. Voids reduce support and can lead to settlement, cracking, or a hollow sound when you walk or drive on the slab.
Water Pooling / Poor Drainage
Water pooling is when water collects and sits on or next to concrete instead of draining away. Poor drainage can speed up erosion, frost damage, and long-term slab problems.
Joints & Movement
Cold Joint
A cold joint forms when new concrete is placed against concrete that has already started to set. It can act like a weak plane or crack if not properly prepared.
Construction Joint
A construction joint is where one concrete pour stops and another starts. It’s a planned joint, not a crack, and may or may not be keyed or reinforced.
Control Joint (Contraction Joint)
A control joint is a planned cut or groove in concrete that encourages cracking to happen in a straight line. It helps control where shrinkage and movement cracks form.
Expansion Joint
An expansion joint is a gap between concrete sections that allows them to expand, contract, and move without pressing into each other. It’s often filled with a compressible material.
Joint Sealant / Caulking
Joint sealant or caulking is flexible material used to fill joints and gaps in concrete. It helps keep out water, debris, and ice that can damage the slab or base.
Seasonal Movement
Seasonal movement is the up-and-down or back-and-forth shifting of slabs with changes in temperature and moisture. In cold climates, this is often tied to freeze-thaw cycles and moisture changes in the soil.
Materials & Products
Aggregate
Aggregate is the sand, gravel, or stone mixed into concrete. It gives concrete most of its strength and bulk.
Bonding Agent
A bonding agent is a product that helps new concrete or repair material stick to old concrete. It’s often used before overlays or patching.
Cement
Cement is a powder that acts as a binder when mixed with water, sand, and stone.
Concrete
Concrete is the finished mixture of cement, water, aggregates and reinforcement that hardens into a solid slab.
Concrete Overlay
A concrete overlay is a thin layer placed over existing concrete to change the surface or add protection. It can improve appearance but doesn’t fix underlying settlement.
Concrete Sealant
Concrete sealant is a liquid or coating applied to the surface to resist water, salt, stains, and wear. It helps extend the life of the slab, especially after repairs.
Epoxy
Epoxy is a strong, two-part liquid resin that hardens into a solid when the parts are mixed together. In concrete repair, epoxy is injected or applied into cracks to glue the concrete back together and restore strength, especially in structural areas.
High-Density Polyurethane Foam
High-density polyurethane foam is a stronger, more rigid foam designed to carry heavier loads. It’s used under driveways, garage floors, and commercial slabs that see vehicle or equipment traffic.
Hydrophobic Foam
Hydrophobic foam is a type of polyurethane foam that repels water as it reacts. It’s useful where moisture is present and you still need reliable expansion and strength.
Mudjacking Slurry
Mudjacking slurry is the thick mixture pumped under sunken concrete in traditional mudjacking. It’s usually made from water, soil or sand, Portland cement, and crushed stone such as Tyndall stone or limestone, and is used to fill voids and push the slab back up, but it is heavy (around 100 lbs per cubic foot) and can add a lot of weight to weak soils.
Polyurethane
Polyurethane is a plastic material made from polymers whose repeating units are linked by urethane (carbamate) bonds. It is usually created by reacting polyols with diisocyanates to form a cross-linked, durable network.
Polyurethane Foam
Polyurethane foam is a two-part liquid material that expands and hardens when mixed. In concrete lifting, it is injected under slabs to lift, level, and support them.
Rebar (Steel Rebar)
Rebar is steel bar placed inside concrete to help it resist cracking and carry loads. It provides tensile strength that plain concrete doesn’t have.
Thermal Insulation
Thermal insulation is any material added to slow the transfer of heat between two areas. Under concrete slabs, insulation helps reduce heat loss into the ground, making indoor spaces more comfortable and energy efficient, especially in cold climates.
Welded Wire Mesh
Welded wire mesh is a grid of welded steel wires placed in slabs to reduce cracking and hold pieces together. It’s often used in driveways and floors.
Structural & Support Terms
Base Material (Granular Base)
Base material is the layer of compacted gravel or crushed stone placed on top of the subgrade before concrete is poured. It helps spread loads and improve drainage.
Compressive Strength
Compressive strength is a measure of how much pressure hardened concrete can resist when being squeezed. It helps describe how strong a concrete mix is.
French Drain
A French drain is a gravel‑filled trench with a perforated pipe that collects and redirects water away from an area like a yard, driveway, or foundation. Water seeps into the gravel, enters the pipe through small holes, and is carried to a safe discharge point so it doesn’t pool against concrete slabs, basement walls, or other structures.
Footing
A footing is the wider concrete base that supports foundation walls, posts, or columns. Problems with footings are structural and different from typical flatwork slab issues.
Foundation
A foundation is the structural base of a building that transfers the weight of the structure into the ground. It’s usually made of concrete footings and walls or grade beams, and problems with the foundation can affect the entire building, not just the surface slabs.
Grade Beam
A grade beam is a reinforced concrete beam that spans between supports and carries loads above the soil. It’s part of the structural system, not just surface flatwork.
Load-Bearing Soil (Bearing Capacity)
Load-bearing soil is the layer of ground strong enough to support the weight of the slab and what’s on it. If the bearing capacity is too low, the concrete can settle or tilt.
Slab-on-Grade
A slab-on-grade is a concrete slab poured directly on prepared soil and base, with no basement or crawlspace underneath. Driveways, sidewalks, and many garage floors are slab-on-grade.
Structural Reinforcement
Structural reinforcement is added material, usually steel, used to help concrete carry loads and resist cracking. In slabs, this is typically rebar or mesh built into the concrete.
Subgrade
The subgrade is the natural soil under a slab. Its condition and compaction are critical to how well the concrete performs over time.
Anatomy of the Job
Compaction
Compaction is the process of pressing soil or base material to make it dense and stable. Proper compaction under a slab helps prevent future settlement.
Cure Time
Cure time is how long it takes the concrete repair material to reach its working strength. With polyurethane lifting foam, this is often minutes, rather than days like with mudjacking.
Injection Holes (Injection Points)
Injection holes or injection points are small drilled openings in a concrete slab that give access for lifting material to be injected underneath. Each hole is typically about 5/8″ to 2″ in diameter and are used to deliver high-density polyurethane foam or mudjacking slurry so the slab can be lifted and supported. During polyurethane concrete raising, temporary injection ports are installed snugly into these holes to connect the injection gun or hose, and once the lift is complete, the ports are removed and the holes are patched to blend with the surrounding concrete.
Injection Ports (Lifting Ports)
Injection ports or lifting ports are the small fittings temporarily installed in injection holes so high-density polyurethane foam can be injected under a concrete slab in a controlled way. The port seals tightly to the hole and connects to the injection gun or hose, allowing foam to flow under the slab without leaking; once lifting is complete, the ports are removed and the holes are cleaned and patched to match the surrounding concrete.
Load Transfer
Load transfer is how weight moves from the slab into the base and soil below. Good load transfer means the slab is well supported and less likely to settle again.
