Sinking Cement

Chuck in FL


The walkway that butts up to my driveway is sinking. What can I do to stop any more of this?

Hope it’s not the kind of sink hole that swallowed up several houses down in FL back around 1980! In that case, drought conditions dried up several underground water pockets and the dry ground above collapsed. For a great majority of sinking sidewalks, during the construction process, perhaps a large root was just an inch or two under the ground. Over time, it rots away and leaves a void and the weight of the concrete will collapse the air pocket. Sometimes, the culprit is water flowing underneath that washes away the foundation soil. Either way, the only way to stop it from sinking further is to reinforce the base. If you have connections with a backhoe operator, this is easy. They can lift the edge of the slab up and you can shovel in gravel or crushed limestone to even out the surface. If you don’t have access to the heavy equipment, then you’re doomed to using…GASP… manual labor! Dig out around the sides to gain access below the walkway. A well-placed hydraulic jack can help. If push comes to shove and money is no object, you can hire a company to “mudjack” the walk into place. This involves drilling some holes in the concrete about 1 ½” in diameter and pumping in a cement or a gravel mixture to raise the slab back to level. The holes are then filled with concrete.