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Can You Pour Concrete Over Rubble?

A lot of people want to know if they can pour concrete over rubble. After all, it’s a much quicker option than digging out the mess yourself. We have researched this topic and have come up with a solution that will give you a good solid foundation.

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Yes, you can pour concrete over the rubble. However, there are some things you need to consider before pouring the concrete. You must make sure the rubble has been properly crushed first into smaller pieces so you can easily level it into the ground.

If you are planning to pour your concrete slab, it is a good idea to keep reading to learn the importance of foundation prep before pouring concrete to avoid any unnecessary headaches down the road. We'll also give you tips on making sure your project looks great from the start.

Worker evenly spreading concrete, Can You Pour Concrete Over Rubble?

Why Is A Good Foundation Important?

It is vital to ensure that you do not skimp on the foundation of a structure. A good foundation is a major part of the house, and you do not want to overlook it. It is also very difficult to repair or replace once you are already inside the house.

It is, therefore, necessary to take adequate precautions when constructing a foundation.

Foundation issues are a common occurrence in houses. Poorly placed foundations are one of the primary causes of cracked floors. When the ground beneath your home is unstable, you can expect cracks in the flooring to occur.

However, there are things you can do to ensure that your house has a solid foundation. We will discuss the factors that make a foundation stable and the methods you can use to protect your home from foundation issues.

What Makes A Good Concrete Foundation?

Whether you're building a home or renovating an old house, it's important to know how to build a good concrete foundation.

This section will give you the basic information you need to build a quality foundation and help you avoid common mistakes that can later lead to structural problems. 

But before that, here are the factors that you should keep in mind when laying a concrete foundation for your home or any structure like a driveway.

A Good Subgrade

A subgrade is a material beneath the concrete slab. A proper subgrade can increase the stability of your foundation by providing a solid base for the foundation above it.

A subgrade should be compacted to eliminate voids, cracks, or other gaps that could potentially weaken the foundation. In addition, compacting removes any air pockets and ensures that the soil is level.

On the other hand, improper subgrade can increase the likelihood of foundation problems, including cracking, sinking, shifting, and warping.

A big pile of rubble on a white background

Subgrade cracks can appear in a variety of ways. From the most common scenario, where water seeps into the ground and causes a localized area of soft subgrade, to the least likely situation, where subgrade shifts and breaks loose because of an earthquake.

In any case, the issue is that these cracks allow moisture to infiltrate and weaken the structure. 

Good Soil

In the process of building a foundation for your house, you should identify the type of soil that your house has. This is because the strength of the subgrade depends on soil type, moisture content, compaction, and topography.

The strength of a subgrade is a measure of how well the soil can support the load imposed on the foundation. If you do not know what kind of soil your property has, you should get your soil tested before laying your concrete foundation down.

In addition, you should also make sure that the soil is free from any organic matter like grass or fallen leaves. As the organic matter starts to decompose, moisture is released.

Moisture can cause soil to become loose. A significant amount of decomposing organic matter can potentially prevent your subgrade from compacting and setting properly. 

Worker holding a concrete pump hose for the house zocallo

Can You Use Rubble As Subgrade For Concrete Foundation?

Using rubble as a subgrade is a great way to save time, money, and effort on a new home construction project. While the typical way to get a building site ready for the foundation is to use gravel and sand, you can also use a large amount of concrete rubble as a subgrade.

You can use rubble as a subgrade as long as it's fine enough to be compacted. The smaller the rubble, the easier it will be to compact. Larger pieces of rubble may require a few passes through a jackhammer to get rubble into a manageable size.

Check out this portable jackhammer on Amazon.

How To Compact Rubble

Compacting rubble into a usable subgrade is a cost-efficient and environmentally friendly way to build the foundation of your property. You can compact rubble by using a plate compactor.

A plate compactor is a machine that compresses materials into a uniform, flat, and dense layer. By using a plate compactor, you can quickly and effectively compact fine rubble to make it easier to work with and to be used as a subgrade.

Compaction is the process of crushing materials together so that they become denser and more solid. The denser the material, the less space there is between each particle. 

Operating a plate compactor is pretty much similar to operating a lawn mower. So if you've ever operated a lawn mower before, you should have no problem operating a plate compactor. The video below demonstrates how to operate it.

Can You Pour Concrete Over Dirt?

Concrete can be poured over any ground or surface. However, it's a bit trickier when pouring it on dirt than most people think.

This is especially true when working on a driveway or walkway project. You have to be sure to check a few things to ensure the surface you're pouring concrete on is a good spot to work with.

Steps In Prepping A Concrete Foundation For A Driveway Or Walkway

  1. You want to make sure that it's level. If the surface you're pouring on is uneven, it may require a bit of leveling. If there are large dips, valleys, or holes in the area, they could cause issues when it comes time to pour concrete. 
  2. You also want to make sure that it's solid. A porous surface could mean that it's full of small holes, which is why you'll want to check to make sure it's solid. A few passes of the plate compactor might be all that you need.
  3. If it's solid, you can now proceed to create a frame around the area you want to pour concrete. This will keep the concrete from spilling out into the wrong place. 
  4. Determine the thickness of the concrete you need to pour. If you're making a driveway, it's going to be at least 10 inches. If you're doing a walkway, you'll probably want to go with about 6 inches.
  5. Once you have an idea of how thick you need the concrete to be, it's time to move on to mixing. Ideally, you should have a ratio of sand to cement that is somewhere between 3:1 and 6:1 ratio for aggregate and cement. 
  6. Pour the cement. Allow it to cure, and cover it with a tarp to protect it from the elements. Make sure there's an allowance so the tarp won't touch the wet concrete. Let the concrete rest and cure.

Man using a machine to flatten the rubble

What Is The Ideal Base For A Concrete Foundation?

Concrete has been used for decades for everything from driveways to sidewalks and as a structural foundation. The mix of cement, sand, and gravel is the basis of all concrete slabs.

This is why several manufacturers will specify certain aggregates in the mix that they feel will work best for their product.

This is because of the different ways that each type of aggregate contributes to the strength of the slab. In addition to the particles' size, the particle type and the ratio of the size of the aggregate to the cement help determine the strength of the finished product.

However, it's been discovered that crushed stone, stone dust, and #57 coarse aggregate are the ideal base for concrete slabs. Each element has different characteristics, such as density, porosity, permeability, hardness, and durability. These properties help determine how well a particular material will perform under certain conditions individually.

However, when these three materials are combined together, they create a concrete mixture that will produce a stable foundation with the ideal combination of strength, toughness, and durability. 

Load Distribution Illustration

How Long Should You Expect Concrete Overlay To Last?

You might be asking yourself how long concrete overlay will last. It is important to know that concrete overlays last longer than the average house paint, but they don't last forever. Nonetheless, you can expect them to last as long as your home does. 

As with most things, some factors determine the length of the lifespan of a concrete overlay, like the weather and how well you maintain it.

What Is The Recommended Thickness For Concrete Overlay?

Thickness is an important factor to consider to make sure you have a beautiful, flawless concrete overlay. Concrete overlay needs to be thick enough to protect the underlying concrete and allow it to maintain its durability. 

On average, you should have a thickness of 1 to 2 inches. This is only a guideline and may vary depending on your specific situation. 

In Closing

Worker evenly spreading concrete

To pour concrete over rubble, you must make sure that the rubble has been properly crushed first. You can do this by using a sledgehammer or a jackhammer to break up large rubble pieces into smaller pieces.

Once the rubble has been broken up into finer particles, you can then use a plate compactor to compact the rubble and make it ready for concrete. The rubble should be able to compact and harden into a solid surface.

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