If the job is of shallow cutting and small scale

In this case, you can use a 4″ or 5″ angle grinder, and a 4″ or 5″ sintered diamond blade, for example, segmented diamond blade, turbo diamond blade, or turbo wave diamond blade, mounted on the grinder. Segmented diamond blades may cause more chips during the cutting due to their segmented rim, but they are cheaper. Turbo wave diamond blades can be used to perform higher load tasks for their strengthened steel core, but their price is the highest in these 3 kinds of sintered diamond blades.

You can first cut the concrete to 1/4″ deep, and see how the angle grinder and the diamond blade respond. If no problem, you can do further passes of cuttings to reach the depth of the cut you need. Each cutting pass should not be deeper than 1/2″.

To reduce the dust, you can ask someone to spray some water onto the diamond blade and the cut during the cutting process. This can also help to cool the diamond blade and extend its life. If it is not safe to use water for the electric power source of your angle grinder, you should cut the concrete dry. As dry cutting uses the air as the coolant, after a period of cutting you should release the pressure on the diamond blade and allow it to rotate freely to let the air cool it. The period can be a few minutes to a few seconds depending on the hardness of the concrete being cut (the harder the concrete, the shorter the cutting period should be).

Throughout the cutting process, you should wear a professional respirator, for the dust can seriously hurt your health.

In addition to angle grinder, you can use a circular saw to do the job. Circular saws have a baseplate which can help to keep the cut straight and uniform. With a circular saw, you can also use a bigger diamond blade, e.g., 7″, to improve the cutting efficiency, for circular saws are stabler.

If the job is of deep cutting or big scale

If your cutting is deeper than 4″ (about 100mm) or the job scale is fairly big, you should use a wet concrete saw and laser welded diamond concrete saw blades to do the job. The concrete saw can be a handheld cut-off saw, a walk behind saw, or another type. The diameter of the laser welded diamond blade is usually no smaller than 12″ (300mm). The concrete saw and the diamond blades can be either bought or rented. To obtain good cutting result and improve cutting efficiency, you can follow below steps to prepare the concrete cutting:

More tips for concrete cutting

• Concrete can also be cut with abrasive blades, but diamond blades are recommended, for diamond blades can provide at least two times faster cutting, less downtime, and constant depth of cuts.

• If you use the diamond blades occasionally and your jobs are small, you can choose the economical grade diamond blades to save your expense (but the cutting speed of the economical diamond blades should be fast enough). If you use the diamond blades frequently or the job is big, you should choose high grade professional diamond blades, for this can decrease your cost per cut.

• If you are not sure that you can do the concrete cutting job well, you can just hire a professional concrete cutting company to do the job for you.

1. What material you want to cut

Diamond blades can be manufactured to be very different for cutting different types of materials. So tell your supplier the material you want to cut, e.g., reinforced concrete, concrete road, asphalt, granite, marble, bricks, or ceramic tiles. The more detailed is the information about the material, the better. For examples, you can tell your supplier the diameter of the steel bars in the reinforced concrete, the aggregate of the concrete, whether it is a green concrete or cured concrete, how hard your marble is, and so on.

2. Wet cutting or dry cutting

If you use a wet diamond blade in dry cutting, it may take just a few seconds for the blade to be damaged, and even worse, this may cause serious security issues. Wet diamond blades and dry diamond blades are designed to be different. So always tell your supplier this information. Concrete saw blades are usually designed for wet cutting.

3. Professional use or DIY use

Professional diamond blades are usually for frequent uses, so cost per unit of cutting length is more important than the blades’ unit price. High quality long-life diamond blades are more cost-effective for professional use though their unit prices are higher.

DIY diamond blades, however, are often for small jobs and occasional use. Their lifespan need not be very long, so cheaper diamond blades with shorter lifespan are an economical choice for DIY jobs. But the cutting speed of DIY diamond blades should be acceptable.

Therefore, letting your supplier know whether the blades are for professional use or DIY use can save your expenses.

4. The horsepower of the saw machine on which the diamond blades will be used

Diamond blades used on big horsepower saw and small horsepower saw are also designed to be different. During the cutting process, big horsepower saw exerts bigger torque on the diamond blade and the blade’s segments receive bigger impact. In this case, the segments’ diamond concentration should be higher to decrease the impact on single diamonds or their bond should be harder to hold the diamonds more firmly. If you use a diamond blade that fits small horsepower saws on a big horsepower saw, the diamond blade may be consumed very quickly. On the contrary, if you use a big horsepower saw blade on a small horsepower saw, the blade may cut slowly or even does not cut because of its high diamond concentration or hard bond. So tell your supplier the horsepower of your saw, and he should know what diamond blades may fit your needs.

5. Make sure the diameter of the diamond blades and their arbor hole size

The diameter of the diamond blades and their arbor hole size should match your saw machine.

6. The segment height

Diamond blades with higher segments will have a longer lifespan. However, the segments cannot be too high. Because during the cutting, higher segments will make the joints (e.g., welds) that connect the segments to the blade’s steel core bear bigger torque. If the joints or welds fail to withstand the torque, one or more segments may break off the blade and may fly out, and may hurt the people nearby. The common segment height of 14″ diamond blades is 10mm or 12mm.

7. The segment thickness

Normally, you do not need to tell your supplier the thickness of the segments. There are default segment thicknesses for different diameters of diamond blades. But if you want to further improve the cutting speed of the diamond blades, you can ask your supplier to make the segments thinner. This often needs the steel core to be made thinner also.

8. Find a good supplier

Finding an honest and reliable supplier is very important. A good supplier can suggest which type of diamond blade can fit your application, and provide you with good products.

1. Choose proper dry-use diamond blades

If you need to perform dry cutting, you should first choose the proper diamond blade which can be used dry. Diamond blades for dry use are normally different from the ones only for wet use. For sintered diamond blades, continuous rim diamond blades are usually only for wet cutting. Most of other sintered diamond blades can be used dry. For welded diamond blades, silver brazed diamond blades cannot be used in dry cutting, while dry-use laser welded diamond blades can. You can read our diamond saw blades introduction article for more information. Dry-use laser welded diamond blades are designed different from the laser welded diamond blades that are only for wet use.

Dry diamond blades usually can be used wet. But if a wet diamond blade is used with inadequate water or even dry, the diamond blade may be overheated and damaged, and even worse, the segment on the blade may break and fly out, and may hurt the operator or the people nearby.

So tell your diamond blade supplier that you need dry cutting, and let him/her choose proper dry diamond blades for you.

2. Operate dry diamond blades properly

After obtaining a right diamond blade for dry use, if the operator fails to operate properly, the excessive heat generated in the dry cutting process may still damage the diamond blade, and the operation can be very dangerous.

Unlike wet cutting using water as the coolant, dry cutting uses air to cool the diamond blade. During dry cutting, the operator should perform intermittent and shallow cuttings to allow the air to flow around the diamond blade.

• Intermittent Cutting: The operator should not do long time continuous dry cuttings. Instead, after some time of dry cutting, he should take the pressure off the diamond blade, and let the blade run freely and to its full speed to allow the air to keep it cool. The duration of each dry cutting operation can be a few minutes to a few seconds depending on the hardness of the material being cut. The harder the material, the more often the diamond blade should be allowed to cool.

• Shallow Cutting: The operator should also perform shallow cuttings to avoid the diamond blade’s overheating. When deep cut is needed, he can do several passes of shallow cuttings (step cut) to achieve it.

• Do not force diamond blade into the material: The operator should allow the diamond blade to cut at its own speed. Forcing the blade may cause overheating and blade damage.