FAQ: What Kind Of Gravel Under Concrete?

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.

What can I use to fill under concrete?

A sand-cement grout can be used to fill voids under concrete slabs. This mix of sand, cement, and water is pumped through holes drilled to fill up the voids.

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.

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.

You might be interested:  Readers ask: How To Lay Concrete Blocks For Retaining Wall?

Do you 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.

Can you pour concrete directly on dirt?

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

Why do you put gravel under concrete?

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.

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.

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.

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.

Do you need plastic under concrete driveway?

If the weather is excessively hot, windy, or dry, the concrete should be protected by covers. This prevents rapid evaporation before finishing begins and avoids plastic shrinkage cracks.

You might be interested:  Quick Answer: How To Make Green Concrete In Minecraft?

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.

What do you put under pea gravel?

Put down the base layer. Gravel composed of 3/4-inch crushed rock pieces mixed with rock dust works best. The crushed rock will add stability to the top layer of pea gravel. Use a garden rake to spread the material evenly to a depth of about 2 inches.

Can you use gravel as a sub base?

Gravel is fine as a subbase providing its compacted well. If you do use gravel it needs to be restrained on all sides to stop it spreading. You would also need to lay the slabs on mortar as sand would simply drain away.

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.

Leave a Reply

Your email address will not be published. Required fields are marked *