This article will answer the question, “how to raise a concrete slab yourself?”. Options on how you can repair your sunken concrete slab are present step by step while also discussing the advantages of each option.
How to Raise a Concrete Slab Yourself?
A sunken or settled slab in your concrete driveway, walkway, sidewalk, or patio is maybe due to the poorly compacted fill dirt or the soil underneath cannot fully support the weight of your slab and the force exerted to it. Sunken concrete sidewalk and other concrete flooring can be repaired by using either of the three options presented below.
Option 1. Mud jacking
Mud jacking involves lifting a concrete slab by pumping a grout throught the concrete and pushing it up from below. This is also commonly known as slab jacking or pressure grouting. The grout is made of sand or finely crushed limestone aggregate combined with Portland cement and water producing a slurry consistency.
Advantage of Mud jacking
- Compared to changing your concrete slab, it involves less convenience and little mess when doing the project.
- It maintains the integrity of your slab sometimes further stregthening the slab. It provides a stable base. Furthermore, it maintaing the color of your concrete.
- There is no noise and waste generated as compared to slab replacement. Noise from breaking the concrete is associated with dust and debris generation. The slab that will be replaced will require to be disposed of in a landfill.
- Area surrounding the project site will not be greatly affected, thus no demolition and re-landscaping are required.
- The repair can be done on any weather condition.
Equipment or tools you need:
- Drill equipped with masonry bit
Common drill used is a gas-powered rotarty percussion drill with 1 to 2-inch diameter. It should have four points and can drill holes that are not “out-of-round”.
Should have at least 7-cubic foot capacity with 10 horsepower engines. It should be able also to withstand heavy use.
- Grout pump
You can use either positive displacement hydraulic piston pumps or hydraulically operated progressive cavity pumps. The pump to be used should be able to deliver pressure from 1 to 100psi and able to fill the sunken slab with grout in a uniform and consistent manner.
Step 1. Drill holes
Using a drill equipped with a masonry bit to drill at least four holes through the slab. The number of holes may vary depending on the size of the slab. Smaller slab requires at least one or two holes in the middle of the slab. Larger slabs, on the other hand, may require three holes.
Also, the thickness of the slab affects the distance of your holes. Commonly, the holes are drilled three to eight apart, but no closer than 1 foot from the edge and as much as possible, should be drilled approximately equal from each other. The usual range of the hole size is 1 to 2 inches in diameter and placed in a manner that the holes will be strategically
Step 2. Prepare the fill material.
Sand-cement grout is a mixture of Portland cement, sand, and water. Sand is the best option instead of pea gravel because it can be easily compacted. Also, this is the most cost-effective fill material, however, disadvantage of using this material includes inextensive void penetration and will require a significant amount of time for the filled concrete to be cured (usually it will take two to three weeks depending on the air-flow. Using a spade, mix the fill material in a wheelbarrow. You can add an expander to prevent the shrinkage of the material during the curing phase.
Step 3. Connect a hose to a mud jacking pump.
Mud jacking pumps will be used to fill your slabs beneath. Run the hose connected to the mud jacking pump to the holes leading to the sunken slab.
Step 4. Pump the fill material to the sunken slab.
Pump in the fill material and set your pump to a 10 psi pressure. Fill in the sunken slab by pumping the material through the hose.
Step 5. Switch to other holes.
Fill the sunken slab evenly by switching the hose to other holes. This is to keep the fill material level underneath your slab to be as even as possible. Continue switching from one hole to another until the sunken slab is completely filled.
Step 6. Fill in the holes.
Fill in the holes with a mixture of concrete mortar. Make sure to level the mortar to the slab using a trowel or a flat wood slab. Then allow the concrete to cure for two to three weeks if you used sand-cement grout. If you use expanding polymer foam, allow tthe foam to sit first for a few minutes for the chemical reaction to occur.
Option 2. Polyurethane foam
Utilizes a polyurethane, a high-density material to be injected through the holse. The fill material will undergo chemical reactions that will initiate the expansion of the foam sealing the void defects.
Advantages of Polyurethane Foam
- Raising sunken concrete slab with polyurethane foam is a cleaner method as compared to mud jacking. During preparation, any spills by mixing or transporting polyurethan foam can be easily cleaned unlike mud jacking grout.
- Lifting sunken concrete slab is less disruptive with foam jacking. Unlike mud jacking in which it requires a series of holes to be drilled in the concrete slab, foamjacking will only require smaller holes of about half an inch wide.
- Polyurethane foam is a lightweight material. Foamjacking reduces the impact to the unstable soil underneath the slab, thus, lowering the chance that the slab will resettle.
- Polyurethane foam achieves slab stability and non-erosive. It does not require curing, thus, the replaired slabs are usable after application.
- It also penetrates hard to reach even the deepest and smallest sinking gaps.
Equipment and tools you need:
- Concrete chalk
- Concrete drill
- ⅝-inch masonry bit
- Shop vac
- Protective gear
- Concrete jack
- Hydraulic Pump and hose
- Polyurethane foam
The steps are almost similar to mud jacking but this option will require less and smaller holes.
Step 1. Prepare the tools and area.
Prepare the tools you are going to nedd and the area you are going to work with. Locate the area where the slab starts sinking. Take the chalk and mark the area
Step 2. Drill then vac.
Using a drill attached with a 5/8 -inch masonry bit slowly drill into the concrete until it goes through the concrete. Be careful to do it slowly to avoid possible cracks to be formed on your concrete and to prevent overheating the bit. Then take the shop vac and remove the concrete dust.
Step 3. Fill up with polyurethane foam.
Get the hose connected to the foam pump injector and put it into the hole then fill the foam all the way up. Move the hose to another hole, make sure that the slab is leveled before proceeding to the next hole. Repeat this step until all holes are filled with the foam.
Option 3. Replacing or repairing concrete
If your concrete slab settles dramatically, there is observable great damage. It is better to just replace the sunken slab. You can do it by removing a section of the slab or totally replacing the entire slab. The disadvantage of just repairing a section is that a new pour on the section removed will likely not match with the concrete in terms of color and texture. This method is the most expensive option in raising your slab.
The step in replacing your concrete forms is the same process as pouring or constructing a new concrete slab. It will also require additional materials such as rebar to again provide support to your concrete slab.
Sunken concrete slab can be a very tedious job repair especially if it involves a large area. There are three options that can be used depending on the availability of your grout material and the how large the damage in your concrete.
For any questions and suggestions about this article, please feel free to submit your thoughts in the comment section below.
FAQs: How To Raise Concrete Slab Yourself?
How much does it cost to raise a concrete slab?
The cost of raising a concrete slab ranges from $500 to $1,207, however, expenses may still vary depending on the size of concrete to lift. Small projects can cost as little as $300 but the cost may raise up to $2,075 for high-end projects and mudjacking is involved.
Is it cheaper to pour concrete yourself?
It is always cheaper to mix your own concrete, just buy bags of cement and add water. You have to be conscious in getting the right cement, water ratio for this will determine the durability of your concrete and then mix it thoroughly. If not enough water was added the concrete may crack or crumbles. On the other hand, if too much water was added it would create a slurry mixture that won;t even harden. You can also opt to use sub-grade concrete. Subgrade concrete is cheaper and you can still obtain quality concrete. You can buy this material at salvage yards.
Does foam jacking last?
Polyurethane foam injection is a long-lasting procedure. Mudjacking usually lasts for long periods, typically 2 to 5 years, but compared to polyurethane, mudjacking is less reliable and requires to be replaced. The injected material for mudjuacking are extremely heaver, usually 30 to 50 times heavier than its equivalent amount of polyurethane injection. It can aslo cause soil compression or foundation sinking underneath the slab. Thus, polyurethane can last much longer than mudjacking if properyl maintained.
How do I raise my basement floor?
Simplest way to raise your basement floor is to purchase flooring tiles that will further elevate your concrete floor. You can opt to have a floating interlocking basement flooring with built-in vapor barrier. This will also allow for air to flow horizontally and vertically if a waterproof plastic base with holes or channels is also installed. Most basement flooring tiles are easy to install, to remove, and to re-install without damaging the flooring.
What is the standard height of one floor?
Standard floor-to-floor height of one floor of a residential building is typically 7.5 feet, for commercial buildings a requirement of 10 feet is to be followed. Residential buildings can have four floors while the commercial building requires three floors.
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