For homeowners: an open thread on "mudjacking"

If you own a house long enough, most of the components will need to be repaired or replaced (a fact often overlooked by young couples eager to purchase as much home as they can afford). Take my driveway.  Please.

Our house is only about 20-25 years old, situated near the crest of a hill overlooking woods.  It's clear that some regrading of the lot was necessary to position it where it is.  The driveway has a series of concrete slabs separated by tiny expansion grooves.  Over the past decade or so, some of the slabs have begun to shift.  These depressions first make themselves manifest in the winter when you are shoveling snow vigorously and the shovel comes to a sudden stop, sending a shudder through your body.

What's happening underneath may represent a "settling" of fill originally used to level the ground or perhaps some erosion as rainwater and winter meltwater work their way between the slabs, perhaps exacerbated by the burrowing of critters like chipmunks or the action of the roots of some nearby very large trees.

The traditional repair method is to hire a construction firm to jackhammer out the concrete, adjust the base as necessary and then pour new slabs.  The alternative is "mudjacking" (sandjacking, slabjacking).  This involves drilling a small hole in the concrete slabs and injecting under hydraulic pressure a material (originally mud or sand, but more recently a polyurethane foam) which fills the space and then lifts the slab until it is flush with its neighbors. (details at the link)

"Jacking" the slabs back up is generally faster, less labor intensive, less disruptive, and less expensive (probably by a factor of 3-5X - I'm still studying that) than removal and replacement of the driveway.  But when slabs are cracked (as some of ours are), there is a risk that the segments will separate, and even a smooth lift of an intact slab may not align perfectly with all the neighboring ones.

I'm writing this post to encourage readers who have dealt with similar driveway/sidewalk problems to respond with comments (for me and for other readers who have - or will someday have- the same problem to deal with), because this isn't the kind of information one learns in school.  Success stories and horror stories are equally welcome.