Slab Lifting and Levelling

The choice depends on access, void size, desired lift, slab condition, groundwater, dead load, return-to-service time, and engineer preference. Polyurethane uses smaller ports, expands quickly, and adds little weight. Cementitious grout provides a mineral fill but uses larger holes and heavier material. Harrowgate selects the system from investigation, not one universal claim.

We assess slab thickness, reinforcement, crack pattern, joint condition, support loss, edges, fixed interfaces, loading, and settlement cause. A sound panel with localized voiding is a good candidate. Severe structural cracking, inadequate thickness, active soil movement, or a failed drainage system can require replacement or ground treatment before lifting is considered.

Accuracy depends on panel stiffness, crack pattern, restraint, void distribution, drainage, and adjacent fixed elevations. Harrowgate monitors movement in small increments with survey equipment and stops at the specified tolerance. The objective can be restoring support and reducing joint faulting rather than forcing a distressed slab to a theoretical elevation that would damage interfaces.

Lifting fills current voids and restores contact, but continued washout, leaking pipes, poor drainage, weak deep soil, or changing loads can create new movement. Harrowgate investigates and corrects the source where included. Broader ground improvement, drainage work, or slab replacement is recommended when the problem extends beyond a localized void.

Yes, injected material can follow open bedding, broken joints, or service penetrations. We review records, scan, locate utilities, monitor drains and pits, limit pressure, and stop if material appears unexpectedly. Sensitive systems may be isolated or camera-inspected. The injection pattern is adjusted to keep grout from entering infrastructure that must remain open.

Return depends on the injection material, hole-repair mortar, panel condition, and load. Polyurethane reacts quickly, while cementitious grout and port patches need specified set and cure. Harrowgate releases pedestrians, forklifts, and heavy vehicles separately where required and confirms that movement has stopped and joints or coatings are safely reinstated.

A suspended slab is not treated like a ground-supported slab. Injecting beneath it can add unplanned load or fill a cavity that is part of the structure. Harrowgate verifies construction through drawings, scans, and openings. Any injection around a suspended deck proceeds only under a specific engineered design, otherwise the concrete is repaired or strengthened by another method.