Polyjacking vs. Mudjacking
Both polyjacking and mudjacking are different types of ‘slabjacking.’ Slabjacking is the means of raising up a concrete slab without digging it up and relaying it. The process involves pumping different materials underneath it in order to force the slab up. Two of the most common types of slabjacking are polyjacking and mudjacking. The differences between the two are fairly straightforward – polyjacking uses a polyurethane foam, and mudjacking uses a type of concrete slurry. The implications of these differences are, however, large.
If you have a slab such as a driveway, patio, or even a parking lot that has begun to sink, there is a wide range of potential causes, including seismic activity, poor drainage, or the wrong type of soil. Depending on the cause and your budget, either polyjacking or mudjacking may end up being the best option for you. This guide will cover the processes as well as the key differences involved so that you are informed about the important issues for you, and you’ll have a rough idea of what costs to expect for your project.
What is Polyjacking?
Polyjacking is the process of injecting polyurethane foam under a slab in order to raise it up and provide a stable base for it to rest on. The process works by drilling small holes into the concrete slab before injecting the foam in at high pressure. As the foam settles under the slab, it pushes the slab up. Once it sets (or ‘cures’), the foam becomes solid and extremely strong. This entire process can take less than half a day to complete.
Traditionally, almost all slabjacking used concrete slurry to raise up slabs. However, once foam-based technology improved, poly jacking is increasingly replacing it as the default option. Most large firms have their own proprietary foam, which is usually tailored to the local soil type.
In addition, because of the ongoing developments in polyurethane technology, the cost of the foam is continually decreasing, and the strength and overall ability of the foam are constantly increasing. Both of these mean that polyjacking is undoubtedly the method of slabjacking that will be more common in the future. It may also be the case that it’s the better option for the present.
What is Mudjacking?
Mudjacking, in comparison with polyjacking, can feel somewhat rudimentary. Where polyjacking relies on space-age technology, mudjacking is a mixture of sand and cement to create a slurry. This is pumped through holes drilled in a slab in order to raise it up.
The best use for mudjacking is when concrete is still very much intact but has just begun the process of sinking or subsiding. Because mudjacking doesn’t have a great deal of power, it struggles to lift particularly heavy slabs – or it may lift them but cause damage to them as it does. If the slab is cracked, then the slurry may leak through the cracks, and it will fail to create the requisite pressure to lift up the slab.
One of the biggest limitations when it comes to mudjacking is that it often holds many of the same problems that caused the slab to sink in the first place. For example, if the heaviness of the slab was the problem, mudjacking (because of its heavy weight) will also sink into the soil. If the problem was that the ground shifts, mudjacking would also be susceptible to cracking. However, because of the simplicity of the technology involved, mudjacking is still a firm favorite. The low costs of materials also keep the entire budget for the project down. There’s a reason why mudjacking as a process is one of the most well-established.
What are the Key Differences?
As suggested by the outline of the processes, there are several key differences between polyjacking and mudjacking. While polyjacking represents the more modern way of lifting a slab, mudjacking is a more traditional method that retains many distinct advantages.
These differences in the process have major consequences for the pros and cons of each one. Although neither is inherently preferable, depending on what project you’re undertaking, there may be one that is better than the other. The below list outlines some of the most important differences between the two.
Because of the process involved in polyjacking, specifically with the nature of foam, the holes drilled in the slab are an inch smaller than those for mudjacking. This can make a major difference aesthetically, particularly over time, when weeds and grass can begin to grow in the holes. The larger holes also make it easier for water to seep through, which may cause further damage in the long term.
As a secondary point of consideration, the fact that polyjacking requires less heavy equipment has an impact on the appearance since it doesn’t cause damage to grass or shrubbery around the process. This helps keep everything neater in the short and long term.
Polyurethane foam cures much faster than mudjacking. The foam used in polyjacking cures in minutes, which means that it’s possible to walk on the surfaces almost immediately. Even in the case of large driveways (or even parking lots), it’s possible with polyjacking to have them up and running in minutes. By contrast, mudjacking takes 24 to 72 hours to fully cure. If you run a business and require the parking lot repaired, the additional downtime from mudjacking may offset any cost benefits you may get.
Aside from the length of time, it takes for the concrete to cure, the other time issue is the length of time it lasts. The way mudjacking provides a base for your slab relies on the underlying soil as the support. This means that the surface is susceptible to freezing and thawing or shifts in the concrete (in short, exactly what caused the slab to sink in the first place).
By contrast, polyurethane foam reacts with the soil underneath and creates the base itself. The hardening of the foam creates a strong and stable base on which the concrete rests. In addition, it helps to set the soil, filling in gaps and providing adhesion. This means that it can last far longer than mudjacking, which tends to last somewhere between two and five years before it needs replacing.
Reaction to moisture
One of the biggest reasons why slabs sink in the first place is the variation when it comes to moisture in the soil. Too much moisture can lead to the soil eroding, and too little causes dry soil that doesn’t support the weight. Polyjacking foam is hydrophobic, meaning that it thrives in wet conditions. It also helps to protect the soil from too much moisture. By contrast, mudjacking can be used in any soil type. In very dry soil, therefore, mudjacking may be a better option.
There is a major disparity in weight between the two different materials. The foam used in polyjacking weighs between 2 and 4 lbs per cubic foot. Mudjacking slurry, by contrast, weighs around 100 lbs per cubic foot. This has a major impact on usage. In weak soil, a heavy substance like mudjacking slurry will compress the soil, potentially undermining the weight of the slab. Polyurethane foam is less likely to do so, which means that it is far gentler on the soil. This avoids the prospect of the slab further sinking under the additional weight of the mudjacking process.
As noted above, there are a lot of advantages that polyjacking has over mudjacking. However, the reason why mudjacking is even still in the conversation is the cost involved. Mudjacking will usually cost you somewhere between $3 and $6 per square foot. Polyjacking, by contrast, has a varying price but will usually come in between $5 and $25 per square foot. This means that polyjacking can run up to eight times higher than mudjacking.
In addition, with mudjacking, you know roughly in advance what the cost will be. The same is not true when it comes to polyjacking, which has a wide range of factors influencing it. Most polyjacking companies have their own proprietary polyurethane foam, which can increase costs. By contrast, mudjacking uses a commonly-made concrete slurry.
Ultimately, only you will know which option of polyjacking or mudjacking is better for your project. Be sure to speak to professionals about the process and get multiple quotes for the work. However, there are several advantages to using polyurethane foam and polyjacking in general. In addition to being a quicker and less invasive process, it cures far faster and is far more enduring. It may cost you more in the short term, but you’ll earn money back by not having to re-do the process every 2-5 years.