Concrete Leveling: Polyjacking vs Mudjacking (2026)

A standard 4-inch concrete slab weighs roughly 50 pounds per square foot. When a slab sinks, the concrete itself is rarely defective—the failure occurs in the supporting earth underneath:

• Poor Subbase Compaction: Builders backfill foundation walls, trenches, and garage approaches with loose soil. If not mechanically compacted in 6-inch lifts, gravity and foot/vehicle traffic consolidate the soil over 2 to 5 years, creating subterranean voids.
• Soil Washout from Roof Runoff: Misdirected downspouts and leaking underground drainpipes wash fine sand and aggregate out from beneath sidewalks and driveways, leaving the slab cantilevered over empty air.
• Clay Soil Shrinkage: Expansive clay soils swell during wet springs and shrink during summer droughts. As the clay desiccates and recedes, the unsupported slab fractures and drops.

Review the mechanical and chemical differences under ACI 546R (Concrete Repair Guide):

Before hiring a contractor to jackhammer and pour a new driveway, evaluate the total project cost comparison for a typical 400-square-foot sunken driveway approach:

Geotechnical polyjacking is a precision process executed with continuous laser monitoring under ICRI 310.1R:

1. Site Mapping & Laser Alignment:A surveyor's optical level or laser receiver is positioned on the slab to monitor elevation down to 1/16 of an inch.
2. Micro-Port Drilling: Using an SDS-Plus rotary hammer drill, small 5/8-inch holes are drilled through the concrete in a staggered grid pattern.
3. Injection Gun Seating: Tapered brass or steel mechanical injection ports are driven into the drill holes.
4. Two-Part Polyurethane Injection: High-pressure proportioning equipment pumps isocyanate and polyol resin into the nozzle. As the components mix, an exothermic reaction expands the foam up to 25 times its liquid volume, generating up to 7,200 psf of lifting pressure under ASTM D1621.
5. Void Filling & Leveling: The expanding foam first fills all subgrade air pockets, consolidating weak soil. Once confined, hydraulic pressure gently lifts the slab back to flush alignment with adjacent sidewalk panels.
6. Patching: The injection ports are removed, and holes are plugged with non-shrink hydraulic cement color-matched to the surrounding concrete.

Not every sunken slab is a candidate for leveling. Inspect the structural integrity before committing:

• Ideal for Polyjacking: Uncracked slabs that have dropped 1/2 inch to 4 inches; slabs with one or two clean hairline control joint fractures; pool decks with trip hazards; garage approaches with settlement gaps.
• Demolition & Replacement Required:Slabs with severe “alligator cracking” (shattered into dozens of pieces smaller than 12 inches); concrete suffering from severe surface spalling, freeze-thaw crumbling, or alkali-silica reaction (ASR); slabs pushed upward by mature tree roots (leveling cannot pull a heaved slab downward).