Concrete slab settlement causes problems. But slabjacking, properly done, solves the problems permanently. It's faster and much less costly to raise a concrete slab than to replace it.
GROUT MIXTURES USED
Grout for slabjacking is usually made with water, cement, and either limestone dust or fly ash. Although fine sand is sometimes also used for grouts, it should be used sparingly. Weak grout may quickly break down or erode, causing the slab to settle again in a short time.
The slabjacking crew needs a rock drill, grout mixer, and grout pump. A rotary percussion drill with a 2- or 2 1/2-inch-diameter bit is normally used.
Slabjacking is as much art as science. You must decide how many holes are needed, their spacing, and the order in which to pump them. You also have to choose the right grout consistency and decide how long to pump grout in any one hole. Unique features of many jobs make it impossible to give hard and fast rules. Before drilling holes, study the slab for clues about settlement causes. By understanding how settlement (and perhaps cracking) occurred you can plan the best lifting sequence.