One of the biggest threats to a concrete slab is empty space beneath it. This is because while a concrete slab is designed to support a tremendous amount of weight, it can only do so when it has solid support below it, that is, from the soil. If the soil shrinks or erosion occurs, the resulting void takes away the slab’s support, and it’s only a matter of time before you notice cracks form on the slab as the unsupported section sinks down to the soil below the void.
A void may also develop when the soil underneath the foundation was not well compacted during construction. Natural compaction occurs after the construction process is complete, and a void develops below the slab foundation, which in turn causes the floor to sink. One of the solutions available for these is mudjacking, also referred to as slab jacking, slab leveling or concrete lifting.
What is mudjacking?
In general, mudjacking is a process that involves lifting sunken or settled concrete slabs by pumping a mixture of water, soil, sand and cement (grout or slurry) beneath the slab to lift the slab. Once the mixture cures, a solid fill remains to stabilize the slab in the desired position. Mudjacking can be used to raise concrete on porches, patios, decks, walkways, driveways and basement and garage floors.
In case of a void below the slab, mudjacking would be useful for filling up the void to prevent further sinking and return the concrete slab to its original position. In other cases, the slab foundation itself settles, or sub-surface erosion occurs, and mudjacking helps to return the floor to its original position.
Mudjacking can be performed by drilling holes through the perimeter grade beam that will then be used to allow the grout into the void. Where only portions of the slab foundation have settled, holes can be drilled through the slab in the settled areas, and grout is pumped underneath the concrete to lift it back to position.
Polyurethane vs mudjacking
In certain cases, it would not be useful to introduce grout to the soil as this would only increase pressure on the soil and lead to further sinking soon after. When this is the case, Polyurethane Foam is used in place of grout because it is much lighter than cement and sand and will therefore not place a heavy burden on the unstable soil.
When injected into the ground, the foam quickly expands to many times its original volume and fills the void, raising the concrete back to its proper level. It also hardens and cures within a matter of minutes, and full functionality is restored in no time. Although it is more expensive than cement and sand, it addresses some of the problems that grout could not adequately take care of.
As a general rule, Polyurethane Foam is more suitably used for load bearing areas. A load bearing wall, for instance, may be more adequately repaired using foam, as it would result in greater support. Another advantage of foam over grout is that smaller holes are required, and fewer holes are needed since the foam easily expands even into areas that are difficult to reach. Further, the use of foam often results in a longer-term fix than grout.
Pros and cons of mudjacking
Mudjacking is much more suitable alternative to removing and then replacing the concrete slab for several reasons:
- It is much cheaper; it costs about a third of the cost of replacement.
- It can be carried out regardless of the weather conditions.
- It is a quick process that will in most cases take a few hours to a day. It allows for almost immediate use, since the soil-concrete-water mixture takes about one to two days to cure before it can bear any load. In contrast, replacing concrete would require about a month before the new slab was available for use.
- It is more cost effective; no damage is incurred to your lawn, so your home’s curb appeal is protected; there is no cement to dispose of.
On the other hand, it is important to understand that mudjacking is not always the best solution for all concrete slab sinking issues. Its suitability is highly dependent on the condition of the concrete slab in need of repair. If it is in good condition, with the surface intact, then mudjacking is certainly a viable option. It is also worth noting that cracks do not always amount to a serious condition, as these can be closed considerably as the concrete pad is lifted.
On the contrary, if the concrete surface is considerably damaged or is crumbling, then removing and replacing the concrete slab would be the practical solution. Mudjacking in such a case would simply be a waste of time and money. The approach would also not be suitable if you want the concrete to look brand new.
Mudjacking cost
The cost of mudjacking varies as there are many factors influencing the total price, the most important being the size and amount of materials needed. Whatever the case, it is more important to seek out professionals that will get the job done right. Going with the cheapest option could mean that the desired effect of the repair work may not last as long as it could.
You also don’t want to risk having this kind of work done by non-professionals as they could cause more harm than good. Be extra vigilant when getting mudjacking work done for your concrete slab foundation, as the result will affect the structural integrity of your home.
G.L. Hunt has been providing top-notch foundation and structural repair services for more than 30 years. We employ the most reliable and cost-effective repair techniques in the industry, and our team has the knowledge and experience to secure your home’s foundation. If your concrete slab foundation or surface has become cracked or sunken, call us and schedule your inspection today.
Check out the full story here: How Much Do You Know About Mudjacking?
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