Quick Answer: What Kind Of Gravel Under Concrete Slab?

What kind of gravel do you put under concrete?

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.

What is the best sub base for concrete?

Gravel and sand compacts best with a drum roller or a vibrating plate compactor. Cohesive soil can best be compacted using a vibrating sheepsfoot roller or a rammer. For small projects, or around the edges, pipes, or columns, a plate compactor provides good compaction for sand or gravel.

How many inches of gravel do you need for a concrete slab?

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

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What size gravel is best for concrete?

Typically the most common size of aggregate used in construction is 20mm. A larger size, 40mm, is more common in mass concrete. Larger aggregate diameters reduce the quantity of cement and water needed.

Do I need gravel under concrete?

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.

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.

Can you pour concrete directly on dirt?

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

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 you need a sub-base for concrete?

When do you need to use a subbase under concrete pavements? The need for a subbase – a layer of granular material placed on a prepared subgrade – depends on the frequency of heavy truck loadings. While mandatory for major highways, a subbase is seldom required for light-duty concrete pavements.

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How many bags of concrete do I need for a 10×20 slab?

A 60-pound bag yields. 017 cubic yards, and an 80-pound bag yields. 022 cubic yards. For a 10 x 10 slab, you would need 77 60-pound bags or 60 80-pound bags.

How do you prepare the ground for a concrete slab?

Preparation is the most important aspect of pouring a concrete slab.

  1. Dig the ground down to the proper depth.
  2. Smooth out the ground with the flat side of a rake so that you have a level surface.
  3. Tamp the ground with a hand tamper or mechanical tamper.
  4. Pour 2 inches of small, rounded gravel for additional drainage needs.

Is sand a good base for concrete?

Pour concrete over a solid, well-drained base



of sand or gravel over clay and other poorly draining soils to provide even support.

What is #2 gravel?

This primarily 1″ crushed, washed gravel with a top size of 1-1/2″ is often used for drainage around perforated pipe, under concrete slabs, and as a coarse driveway topping for soft, very muddy driveways. Suitable as a coarse driveway topping.

How much gravel do you need under a garage slab?

If it holds its shape, it’s about right. The safest approach is to remove the topsoil and place a minimum 4-inch layer of compactible gravel or crushed stone as a base over the undisturbed subsoil.

How much does a dump truck load of gravel cost?

The cost of gravel ranges from $10 to $50 per ton, $15 to $75 per yard, $1 to $3 per square foot, or $1,350 per truck load depending on the rock type, volume, and travel distance. Delivery is included up to 10 miles. Gravel spreading costs $12 per yard or $46 per hour.

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