Readers ask: Sand Or Gravel Under Concrete Slab?

What is the best base for concrete slab?

Most concrete contractors want a mix of coarse and fine aggregate to create a compactable base that is going to be safe for settlement and drainage. Crusher run (a mix of crushed stone and stone dust) is one of the best base materials for concrete flatwork.

Can I use sand under concrete slab?

Pour concrete over a solid, well-drained base

Because concrete slabs “float” on the soil, soft ground or voids underneath may cause unsupported areas to crack under heavy weight like vehicles. Pack about 4 in. of sand or gravel over clay and other poorly draining soils to provide even support.

What type of gravel goes under concrete?

Backfill beneath concrete flat-work along foundation walls should be accomplished with a granular material that is uniform in size. Some fill materials, such as round stones like pea gravel, tend to be self compacting. “I recommend open-graded granular material be used,” says Tull.

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What do you put under concrete slab?

Whether you pour concrete for a walkway or patio, a strong gravel base is required to prevent the concrete from cracking and shifting. Gravel is especially important in clay soil because it doesn’t drain well, which results in water pooling under the concrete slab and slowly eroding the soil as it finally drains.

Can you pour concrete directly on dirt?

Long story short, yes you can pour concrete over dirt.

Should you put plastic under concrete?

Recently, though, research has shown that the old traditional layer of 6-mil Visqueen (polyethylene plastic) under the slab is seldom effective for two main reasons: Although it may seem water-tight, this grade of material allows a lot of water vapor to pass through.

Do I need sand under concrete?

To prevent cracking and crumbling, concrete patios need to be built on solid, well-drained soil. If you live in a region with lots of clay in the soil, you will need to dig down further and backfill with layers of compacted sand and gravel.

Do you need rebar for 4 inch slab?

No, you do not need rebar for a 4inch slab of concrete on grade. A 4inch-thick slab cast on the ground and in permanent contact with it will float and rebar is not required. Rebar is recommended on concrete measuring 5 – 6 inches thick.

Do I need gravel under concrete slab?

Because concrete is a very porous material, it will absorb any moisture that it contacts. This can cause pooling. Without crushed stone, pooling water will settle under it and erode your slab. Adding a layer of crushed stone will add proper drainage, as well as create a barrier between your slab and the ground.

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Can I use pea gravel under concrete?

If you use pea gravel beneath a patio, take a few simple steps to ensure the stability of the base before setting your surface stones, pavers or bricks. Click to see full answer. It should be ok to pour concrete over your gravel walk although you might want to give the concrete a little more depth along the sides.

How much gravel do you put under concrete?

Excavate the slab area to a depth of about 7 inches, allowing 3 inches for a gravel base and 4 inches for concrete.

How do you prepare the ground for a concrete garage floor?

Good ground preparation starts with removing the topsoil. Then, if the soil has not previously been “disturbed” (i.e., dug up), a four-inch layer (minimum) of gravel or stone should be added. (Soil that has been dug up before should be compacted.) The gravel or stone also needs to be compacted.

Do you pour concrete before or after pole barn?

New member. The only way to build a pole shed that will last and look good forever is to pour the floor first. The treat post rot out in about 10-15 years if they are in the ground. pour the walls put the post on the cement floor and it will last forever.

Is quikrete as strong as regular concrete?

Quikrete fast setting concrete is just as strong as regular concrete. Concrete gets its strength from a chemical reaction that occurs over time during curing. After it’s had time to cure, which usually take 28 days to complete, Quikrete can reach strengths up to 5000 psi.

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