Do you have to put hardcore under concrete base?

The ground should be levelled and well compacted using a small garden roller or a lump hammer to provide a base for your concrete. A layer of hardcore of a minimum of 100mm is needed for a sub-base and should be well compacted.

Why do you need hardcore under concrete?

What is Hardcore Used for? A hardcore bed provides an essential part of a strong foundation for building work; when well-compacted it gives a base in which the builder can have confidence when infilling the upper layers. This is an invaluable commodity when it is necessary to raise the level of a floor.

What do you put under concrete base?

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.

Do you need base 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 I put a concrete base on soil?

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

HOW TO: Lay a concrete base - perfect for a shed or extension

Can you pour concrete without gravel?

Yes, you can pour concrete over dirt. If you have a very compact soil-type, such as solid clay, then you may have ground that is solid enough to support a slab over a period of time.

Can I pour concrete over rock?

Big rocks are not a problem as long as there is uniform concrete coverage and adequate rebar for temperature fluctuations. If the big rocks protrude up above grade and if you have a few in a row, it will weaken the slab. We like things uniform, including the grade, thickness of the concrete, etc.

Can you pour concrete on sand?

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.

Can you pour concrete over grass?

Cheap and versatile and easy to pour, concrete will last you years down the road. You can pour it just about everywhere—including on the grass. Although it takes a little work, pour concrete over grass to create that walkway you always wanted or that mowing preventative you could previously only dream about.

Can I pour concrete over gravel?

Cement mix might work in some cases over an existing gravel driveway. Laying a concrete driveway over an existing gravel one is possible, but it is not generally recommended. The kind of gravel that is intended to go under cement is typically a smaller grade than what is used for gravel driveways.

How thick should a concrete base be?

In general, 6 inch (150mm) slab thickness is considered for residential and commercial buildings with reinforcement details as per design.

How much gravel do I need under concrete?

Determine the depth of the excavation. Let's say it's d = 2 yd . Multiply the area and depth of the excavation to obtain its volume in cubic yards: 18 * 2 = 36 yd³ . The volume of gravel required is equal to the volume of excavation.

What is the point of hardcore?

'Hardcore' is the construction term used to denote 'engineered' infill material that is placed within the confines of a building foundation (after removal of any unsuitable ground layers) in order to support a ground-bearing floor slab (Figure 1).

Can I use old bricks as hardcore?

No as you would get uneven settlement.

Can I use ballast instead of hardcore?

Ballast is available in different types for different needs. 0-20mm ballast is perfect for sub-base and concrete foundations. 20mm screened ballast is versatile and can be used on driveways, footpaths, oversite fill as well as sub-bases. Raised ballast is reserved for backfill, driveways and binding hardcore.

Is gravel or sand better under concrete?

As a general rule, stay away from using sand as a subbase. You're better off using gravel; your concrete will last longer and have less of a chance of cracking over time.

Can you pour concrete directly on sandy soil?

Failing to Prep the Site

If you're lucky enough to have sandy soil in your yard, you can simply remove the grass and topsoil and pour a layer of gravel for extra drainage. Make sure the surface is firm and level before you start pouring concrete as well.

Is sandy soil good base for concrete?

Sand does not take on water like clay and peat. This means that a concrete foundation constructed on sandy soil does not generally have an increased risk of cracking as a result of fluctuating water content in the surrounding ground. However, there is another potential problem with sand.

What type of stone do you put under concrete?

The base in concrete construction is usually a form of crushed stone. 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.

How much hardcore do you need for a concrete slab?

A layer of hardcore of a minimum of 100mm is needed for a sub-base and should be well compacted.

Can you pour concrete on uneven ground?

Concrete slabs have a variety of uses, including home foundations, walkways, and patios. If you pour your concrete on uneven ground, the slab may look crooked or get damaged as it dries.

Can I make concrete with just sand and cement?

Can I make concrete with just sand and cement? No, you can't make concrete with only sand and cement. Concrete isn't considered concrete without aggregates like gravel and stone. It's the aggregates that contribute to concrete having high strength.

How thick should the base be for a concrete driveway?

Most residential concrete driveways are 4” thick and placed on a compacted 4” to 8” thick base of gravel or crushed stone. Adding rebar can double or almost triple the strength of a standard 3,000 PSI concrete driveway. Increasing to 5” will increase the strength by about 50%, and even more with rebar.