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Slabjacking to fix cracked sidewalks

cracked sidewalkSlabjacking (AKA mud jacking or leveling) raises the section of a sidewalk so it is even with a portion that was lifted by tree roots. Slabjacking consists of pumping a new base material (grout) under the sunken concrete, raising and supporting it.

One or two holes 1.5 to 2 inches diameter are drilled in the slab to be raised and grout injected at 600psi. Grout is made from portland cement, limestone, water and perhaps fly ash. This produces a stable, long lasting foundation under the slab according to Steven Cothrel, City of Upper Arlington, OH.

A plastic cap is inserted into the hole and a small amount of morter mix placed on top of the cap to blend with the slab. For more information and the location of slabjacking contractors, check the "concrete" categories in your Yellow Pages.

Slabjacking one slab takes about 30 minutes and cost about $40 to raise one section of sidewalk. This compares favorably with concrete replacement which can cost up to about $275 per section. Pedestrians can walk on the raised slab immediately. More than one section of sidewalk may need to be raised to provide a gentle slope if roots have lifting a slab more than about 2 inches.

The section to be raised in the photo at right is the one at the extreme bottom of the image. One or two holes are drilled in the slab section to raise it up even with the sections that were raised by the tree roots.