Cutting Depth In terms of cut depth, specialists propose cuts ranging from one-quarter to one-third the thickness of the slab. Simply explained, for an 8-inch thick concrete slab, the cutting depth should be limited to roughly 2.5 inches. Larger cuts may require more than one pass with a reciprocating saw.
The deeper the cut, the more damage you will do to the annealed color and texture of the surface. Also, the deeper the cut, the more difficult it will be to restore the concrete once it has been damaged. Finally, deep cuts can expose metal reinforcement within the concrete, which could lead to a future problem if not addressed before cementing over the hole. For these reasons, we recommend that you limit yourself to shallow cuts when working with concrete.
Shallow cuts are recommended for several reasons. First, they're easier to clean out after you've poured your concrete. Second, they don't go as deep, so there's less risk of damaging the surrounding area. Third, they don't require special tools; any standard power tool will work fine. Last, but not least, shallow cuts look better!
If you want to make deeper cuts, such as those required for plumbing or electrical lines, then you will need a mechanical breakaway blade. These blades will separate at a predetermined tension, which prevents them from being pulled into the concreted piece.
A decent rule of thumb is to cut the joints one-quarter to one-third the thickness of the slab. 1. For a 6-inch-thick slab, this requires a 1.5- to 2-inch-deep cut. 2. The deeper the cut, the longer it will last. 3. If you don't like the look of exposed concrete, such as for patio areas, put a stone or brick border around the joint to hide it.
4. Concrete cuts easily, so use a sharp chisel to make the first cut, then smooth out the edge with a float or mallet.
5. Wear protective clothing and equipment while working with concrete. In particular, wear safety goggles when cutting or grinding concrete. Protective gloves are also useful if you plan to work with abrasives such as sandpaper or grit.
6. Clean up after yourself! Remove all your tools and materials from the job site each day. Otherwise, you might be surprised by a visit from the police due to trespass signs.
7. Don't pour concrete on top of an existing slab unless you want to end up with two separate slabs instead of one continuous surface.
8. Don't pour concrete over old wiring or other objects that could be damaged by electricity.
Most retail or commercial concrete slab standards call for a thickness of 4 to 6 inches. Historically, owners and contractors have disagreed over whether a poured slab fits a standard due to its thickness. However, most codes now require that slabs be rated by their total volume, not their maximum thickness. Thus, a contractor could easily pour a concrete slab that meets the standard, even if it's more than 6 inches thick.
The typical home driveway is 2 to 3 feet wide and 8 to 10 inches deep. A layer of compacted gravel serves as a base for the driveway, but this layer needs to be at least 1 inch thick to avoid washing away in heavy rain. The concrete itself should be at least 1 foot thick.
Concrete is easy to cut with tools, so don't just throw together a slab without considering how much it will weigh when dry. In fact, according to the American Concrete Institute, the average price of a residential concrete slab is about $7000. That's not including the cost of equipment or the labor needed to mix and pour the slab.
The first thing you need to consider when pouring a concrete slab is its thickness. Thicker slabs are easier to pave than thinner ones-they don't crack as easily under traffic or when you walk on them. The second thing to think about is its width.
In residential building, the normal thickness of a concrete floor slab is 4 inches. If the concrete will be subjected to severe loads on occasion, such as mobile homes or garbage trucks, a thickness of five to six inches is advised. Concrete that is 8 inches thick is used in commercial buildings because it can sustain heavier traffic without deteriorating more rapidly.
The best way to determine how much concrete you need is to calculate how much wet weight it is going to be and then multiply that number by 0.0333 to get the total volume. For example, if you need 100 cubic feet of concrete then you would need 33 3-inch buckets of concrete.
Concrete slabs are either poured in place over an existing structure or placed in a flat bed and then lifted into position. Poured-in-place slabs are usually thicker at the bottom than they are at the top to provide room for expansion as the concrete dries. The slab's surface may be finished or left raw. Poured-in-place slabs can be cut to size with a power saw if needed. Lifting slabs requires a crane or similar device. The type of finish applied to the surface of the slab affects its cost considerably. A rough-textured surface requires less work and costs less than does a smooth surface.