Concrete Leveling - What Is Slabjacking

What Is Slabjacking

Slabjacking is a specialty concrete repair technology. In essence, slabjacking attempts to lift a sunken concrete slab by pumping a grout through the concrete, effectively pushing it up from below. The process is also commonly referred to as "mudjacking" and "pressure grouting" as well.

Accounts of raising large concrete slabs through the use of hydraulic pressure date back to the early 1900's. Early contractors utilized a mixture of locally available soils (sometimes including crushed limestone and/or cement for strength), producing a "mud-like" substance and thus the term "mudjacking". Modern slabjacking contractors can now utilize an expanding polyurethane foam, providing a multitude of benefits when compared to traditional slabjacking materials.

The slabjacking process generally starts with drilling small diameter access holes in the concrete, strategically located to maximize lift. These holes are generally 5/8" diameter for urethane slabjacking and can be over 1" in diameter for traditional mudjacking applications.

Initial material injections will fill any underslab void space. Once the void space is filled, subsequent injections will start lifting the concrete within minutes. After the slabs are lifted, the access holes are patched and the work is complete.

The process is very rapid when compared to traditional "rip and replace" applications and is minimally disturbing to the surrounding areas.

Slabjacking technology has several limitations. Most importantly, poor quality concrete may crack and/or deteriorate when being lifted. This is especially true for slabs that are less than 4 inches in thickness. Cracks can also develop in the concrete during the lifting process. Slabs built over filled-in land and/or poor subsoils can also be susceptible to further settlement.