Slab Lifting & Re-support for a Warehouse End-of-Lease Make-good

This movement exposed the dowel sleeves between the adjoining concrete elements, creating uneven access levels and reducing the ramp’s serviceability.

Elsewhere, a section of the car park had subsided by up to 300mm, causing significant ponding and preventing stormwater from draining effectively to the external gutter. Within the office, kitchen and toilet facilities, substantial voiding beneath the slabs had resulted in settlement, sinking floors and cracking.

The movement was considered likely to have resulted from a combination of subgrade movement, inadequate compaction and the progressive loss of support due to rainwater ingress. Without treatment, continued traffic loading and moisture ingress could have caused further settlement and reduced the serviceability of the affected areas.

Before drilling commenced, underground sewer, water, stormwater and electrical services were located throughout the treatment areas. Small injection points were then drilled through the slabs, allowing Teretek® engineered resins to be delivered into the voided and poorly supported ground beneath the concrete.

External injection rods were installed to treatment depths of up to 1.5 metres. Injection began at the lowest sections of the affected slabs, with the expanding resin filling voids, compacting suitable surrounding material and progressively improving ground support.

Once sufficient resistance had been developed beneath the slabs, further controlled injections generated the lift required to correct the affected levels. The slabs’ response was continuously monitored throughout the process to maintain control of the lift and minimise stress on the concrete and adjoining structural elements.

Internal works were completed within the kitchen and toilet areas, where the slab was found to be approximately 400mm thick. Resin was injected at depths of approximately 1.0 metre to fill the extensive underlying voids, restore slab support and improve the internal floor levels.

More than 160mm of lift was recorded during treatment, correcting the substantial differential movement across the 19-metre section.

The car park slab was successfully re-supported and re-levelled, restoring the required surface falls and allowing stormwater to drain effectively towards the external gutter rather than ponding across the pavement. Internally, void filling and re-levelling works lifted and re-supported the office amenity slabs, resulting in the partial closure of existing cracks and slab joints.

Across the two-day project, approximately 1,060kg of engineered resin was injected. The completed works restored support and serviceability across the affected areas, allowing the property’s end-of-lease make-good requirements to be completed without removing and replacing the existing concrete slabs.

Learn more about Mainmark’s commercial slab lifting solutions.