Mudjacking is not new. This technique used to lift and level sunken concrete slabs has been around for over 70 years. The mudjacking process works by pumping a slurry (typically comprised of a mixture of sand, cement and/or soil) below a slab through holes at the surface. The hydraulic pressure from the mudjacking machine causes the slab to rise. Mudjacking works however this repair process is not without its faults. Below I explain three main problems with mudjacking that property owners need to be aware of before selecting a repair solution.
The material used in mudjacking is not waterproof and not ideal for our northern climate. As water drains below the concrete and is exposed to freeze/thaw cylces, the sand, cement and soil material is susceptible to shrinking, erosion and breakdown. This material breakdown can cause the concrete to sink again.
The material pumped below the concrete (if done correctly) is going to be rock solid after 24 hours. That is a good thing however it’s also going to be extremely heavy and that’s not good. The weight of the original concrete over a poor base is usually what caused the slab to settle in the first place and by adding additional weight over the base you’re asking for additional settling to occur.
In order to pump the thick material below the slab, large holes (1” – 2’ inches) need to be drilled. Along with being an eyesore, these large holes compromise the structural integrity of the concrete, which can cause cracking to occur.
Introduction of Polyurethane
In the 1980s state and federal transportation engineers started injecting high-density polyurethane below sunken roadways. This method was selected over traditional mudjacking due to polyurethanes light weight and durability. Also, polyurethane cures in only 15 minutes verses 24 hours with mudjacking – a critical benefit when dealing with busy roadways. For the next twenty years the polyurethane injection or polyjacking method was patented and installed by only one company, mostly on highways and large projects.
In the early 2000s the polyurethane injection process patent expired. Now the material and process is available to all contractors to use. This has caused it to be economically feasible to use on residential projects such as driveway, walkways, garage floors and patios. Polyjacking is now the industries preferred method for raising and leveling sunken concrete due to its longevity, small injection holes and quick return to service.