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You will need 3 inches of gravel under a concrete slab that is 4 inches thick. More gravel is better, but 3 inches is the minimum amount of gravel you should have with a 4” slab. Use ¾” washed and screened gravel, then compact it to level.
Can you have too much gravel under concrete?
Adding crushed stone under your concrete slab will provide a level surface for your foundation. Simply pouring concrete onto the ground will expose it to elemental erosion that will cause cracking and sinking. Similarly, if there are roots or plants under your slab, they may rot and cause unevenness.
How do you calculate gravel base for concrete?
One cubic yard of gravel weighs 2,700 pounds. One ton is 2,000 pounds. Divide 2,750 by 2,000 to get 1 3/8 for the weight of each ton. Multiply the cubic yards by 1 3/8, or 1.375 in decimal form, to get the amount of gravel needed in tons.
What kind of gravel do you put under concrete?
Depending on what the driveway will be used for, the base may need to be 4 to 12 inches. Ideally, 6 inches of crushed stone or gravel should be used for most driveways. Proper application requires that the driveway hole be dug out, and the soil has to be prepared.
How much base is needed for a concrete slab?
Every concrete slab should have a minimum slope of 1/8-in. per foot to keep water from pooling.
Can I pour concrete directly on dirt?
Long story short, yes you can pour concrete over dirt.
Can you sprinkle cement 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 do I calculate how much gravel I need?
Measure the length and width of the area in feet and multiply the figures together. Multiply your area figure by the depth of gravel that you wish to use, ensuring your measurement is also in feet. If your depth is in inches, divide it by 12 first. You now have a cubic feet volume figure.
How deep should you lay gravel?
Decorative aggregates should be laid at a depth of 50mm. This ensures proper coverage without revealing the surface below. Laying the gravel too deep will mean you sink into the surface and it becomes difficult to walk across.
How many square feet will 5 tons of gravel cover?
Regarding this, “how much area does 5 tons of gravel cover?, typically, as 1 ton of gravel cover around 108 sq ft area for 2 inch depth, so 5 tons of gravel = 108 × 5 = 540 sf coverage, therefore 5 tons of gravel can cover around 540 square feet or 60 square yards or 50 square meters area for standard 2 inch depth.
Do you need to put 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.
How many yards of concrete do I need for a 24×24 slab?
For example, for a concrete slab that is 24′ X 24′ X 4”, simply enter 4 in the Thickness/Depth field, 24 in the Width field, and 24 in the Length field. Click “Calculate”. Your answer should be 7.11 yards. Note: The Concrete Volume Calculator can also be used to determine yardage for aggregate products.
How do you crush concrete into gravel?
Strike the slab with a sledge hammer about 12 inches from the point where the pickax touches the underside of the slab. Do this repeatedly, and after a short time the slab will break up into small pieces.
Can I use gravel as a sub-base?
If your builder uses the gravel he may find it will dissipate too easily into the ground and will spend more time and money to get the levels needed. I would not advise using the gravel. A well constructed base means your drive will never get sink holes.
Do you need rebar for 4 inch slab?
The thickness of rebar should be no more than 1/8 that of the slab, so a 4” slab shouldn’t have steel greater than #4 or 1/2″ bar. It’s best to check with a Structural Engineer if your slab will bridge or cantilever. What is this? For 4” concrete slabs used for driveways and patios, #3 rebar is common.
Can I use concrete as a sub-base?
Any potential ‘soft-spots’ in the subgrade can allow the concrete to sink from the center or turn up from the edges. Owing to its inflexibility, the concrete slabs can crack. As concrete is highly compressed and heavy, it may crack under its own weight if not provided a suitable sub-base.
How long does it take for 4 inches of concrete to cure?
Your concrete should be solid enough to walk on, without leaving footprints, after anything from 24 to 48 hours. By seven days, your concrete should be cured to at least 70 percent of its full strength.
