Info | Mudjacking 101 In Denver
Mudjacking is the process of pumping a water, sandy loam soil and cement mixture under a concrete slab in order to lift it. This mixture is called slurry. The exact ingredients vary from company to company, and from job to job. Mudjacking can be the solution to many homeowners’ sunken concrete problems including stailizing slabs that have voids. It may also be called concrete leveling or slabjacking.
Concrete can sink or settle for several reasons. If the original concrete was installed on dirt that had not been compacted properly, the slab will start to settle within a few years. Once the concrete does start to tilt or sink it can cause walking hazards, unwanted water runoff, or major foundation issues.
There are several factors to consider when choosing a mudjack contractor. The first step is to have a contractor come to your house and determine if the concrete slab is a good candidate, be very skeptical of telephone estimates. A concrete slab must be intact, in good shape and at least 30” wide to be a possible candidate. If a slab is broken into small pieces it is best to have it replaced. I have raised slabs 12” in elevation.
Concrete begins to get softer or weaker as it becomes old. There are some exceptions but usually concrete over 40-50 years old should be replaced.
Most residential concrete is poured 2,500 PSI (pounds per square inch). The higher the P.S.I. the stronger the concrete is.
Mudjacking starts by drilling a series of holes through the concrete slab. The size of diameter varies with different contractors. Ours is 1 5/8” diameter hole and these holes are approximately 4’-6’ apart from each other.
Next we hydraulically pump a soupy mud slurry into the holes. Each contractor has his own mix for making the slurry. Once the void is filled under the slab, the slab begins to raise up to its’ proper elevation. Often there are voids under slabs that need to be filled to stabilize the concrete without raising the slab.
Stabilizing these slabs help prevent future damage.
Interior floors that have heat vents in them are not good candidates for mudjacking. The mud slurry can get into the upperground vents. Filling the heat vents with mud makes them ineffective.
The most important part of mudjacking is to make sure the voids under the slab are filled in. There are contractors that have undersized equipment (not enough material). Sometimes slabs are raised on collars like ant piles, leaving voids. This method takes about half the material to raise a slab and gives the industry a bad name. Because the job is only half done, it will fail in the future. Be careful about choosing the lowest estimate, you may get what you pay for.
- James Warner, Professor at the Colorado School of Mines warns that the use of polyurethane foam can result in significant voids underneath the concrete [Warner, James. Practical Handbook of Grouting: Soil; Rock; and Structures. N.p.: n.p., 2004. Print.]
After raising or stabilizing a slab it’s time to plug the holes with cement. Not all contractors take time to do a good job. Check reviews to see who has pride in their work.
We use a portable pump so we can custom make each batch of material for its’ proper thickness. Our portable has a short hose so we can change the thickness at a moment’s notice. Some contractors pump slurry from the street making it much more difficult to control the thickness of the slurry. Having the wrong thickness in a hose can leave the operator wondering when the proper thickness will arrive which can be very problematic.
No mudjack contractor will guarantee they won’t crack the concrete slab when raising it. Using the proper thickness of slurry greatly reduces the chance of cracking the slab. There are other factors that are out of our control that can cause a slab to crack.
Our company has invented in-house equipment that greatly reduces the chance of cracking the slab and the slurry we use will not harm grass.
After an exterior slab is raised it is a good idea to put a commercial grade water sealer on it. For my own house I have bought sealer at Smalley & CO and Rio Grande, be sure to ask about a spray applicator that makes it easy to apply the product.
Keeping a good sealer on the concrete prolongs the life and look of the concrete. Putting the sealer on helps prevent the concrete from pitting or what is called spalling (when small pieces of the surface come off). Mudjacking can save up to 80% compared to replacement cost.
Winter is not a great time to mudjack. With the temperature being around 32 degrees, it can cause ice on the concrete, which in turn can cause accidents. When the ground is frozen it holds the concrete and won’t release it until temperatures rise in spring.
Because of our alluvial soil conditions in Colorado, a one year warranty is a fair warranty. Be careful of longer warranties and who is offering them. Most concrete contractors don’t offer any warranty for the new poured concrete.
Ready to get an estimate? Give us a call. We are getting ready for another busy season and want to make sure we get your project on our schedule. We look forward to hearing from you.
Too many mudjack contractors are undersized with their equipment. Not having enough material on the truck can be a huge concern. Some contractors will pump the slurry into the slab too thick. This raises the slab on collars, or “ant piling”. There are still voids left under the slab, meaning the slab was never totally stabilized. This practice really hurts our industry. Because the lift wasn’t done correctly, it has a greater chance of failing in the future. AAA drives a semi truck to the work site that carries about twice the material as our closest competitor. Our semi truck stays on the street to prevent damage to your lawn. We are never concerned about running out of material and being able to do the job right. For over 25 years, AAA has been the leader in concrete raising in Colorado.