How to Cut Concrete Blocks With a Circular Saw?

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On the road to becoming a master at carpentry and woodworking, one must first learn the basics. Such as, how to cut concrete blocks with circular saw the right way. 

Cutting through robust materials can indeed be intimidating. It’s not uncommon for beginners to end up with pieces that are the wrong size. As an expert in this field, I’ll guide you through each step of the process meticulously to prevent this from happening. This comprehensive step-by-step guide is designed to make the task manageable, even if you’ve never done it before.

5 Steps to Cut Concrete Blocks With Circular Saw

Step 1: Strap on your Safety Gear

All excellent craftsman know the importance of safety gear. At heightened temperatures, concrete blocks release silica dust which is harmful to your health.

green circular saw on wooden surface

For this reason, make sure to wear the following: 

Step 2: Mark the Cutting Path Using a Chalk Line

Before you make a cut, prepare the concrete block by using a chalk line. Speaking from experience, this simple tool will act as a crucial guide for your blade and circular saw during the cutting process. I’ve consistently found that a well-drawn chalk line ensures straight, precise cuts, making your job not only easier but also more professional-looking in the end. Trust me, it’s a step worth taking the time to do right.

Step 3: Adjust Your Circular Saw

Set the ripping size or cutting depth of your circular saw to 50mm. Once down, align your blade with the mark you made using the chalk line. 

adjusting circular saw blade depth

Once everything is set, turn on your saw and let it reach max speed or its maximum rate of revolution.

Step 4: Start Cutting Slowly

First things first, you’re job when cutting using a circular saw is to lead your saw and blade, not exert pressure or effort. 

In other words, trust your blade to let it do its thing: cut and rip the concrete block. Simply guide it along the chalk line without exerting extra force or excess pressure. 

Step 4.1 (Optional): Add a Stream of Water to Your Blade

Taking this next step is optional, but advisable if you’re using a wet blade. When I’m cutting a concrete block with a wet blade, I often have an assistant help me by adding a stream of water to the blade during the cutting process. From my extensive experience, I can tell you that this added measure not only cools the blade but also minimizes dust, creating a cleaner and more efficient cutting environment.

cutting concrete with circular saw

The stream of water added to the blade can help cool the blade and prevent harmful toxins like silica dust [1] from entering your system. 

Step 5: Stop Cutting After 45 Seconds Then Cut Again

The last thing you want is your blade overheating and cutting the concrete block inaccurately. 

During the cutting process, make sure to stop every 45 seconds, then cut again. If you cut continuously without rest, your blade will heat up and produce unfavorable outcomes.

Blades to Use When Cutting Concrete Blocks

You have three options available to you: 

  1. Diamond Blades
  2. Masonry Abrasive Blades
  3. Wet/Dry Cutting Blades
circular saw blade

Diamond blades are the most durable, does not wear out easily, and is more suited to those who frequently perform concrete cutting jobs. 

Masonry abrasive blades are the most affordable and inexpensive but lack the durability and cutting speed diamond blades have. Using masonry abrasive blades means you’ll have to replace it a lot more often than diamond types. 

Wet/dry cutting blades are also diamond blades, making them great choices but the main concern is how hot they become during the cutting process. 

A wet circular blade of a Rotorazer circular saw, for instance, will require you to run a stream of water as mentioned in optional step 4.1 to prevent silica dust from being produced. 

Dry circular blades can expel heat much better but produce higher amounts of silica dust so respiratory masks are a must.

Which Blade Should You Use?

If you’re planning to do a one-time job or a quick woodworking session, it’s recommended to use masonry abrasive blades.

diamond blade cutting through tile

If you have regular concrete jobs, diamond blades work best. 

I would only recommend using wet cutting blades if you have a specific circular saw equipped with special parts designed to add a stream of water during the process. Having expert knowledge in this area, I assure you that these specialized components are crucial for effective wet cutting, facilitating smoother operations and more precise results.

When Is the Best Time to Cut Concrete?

This depends on the weather conditions, timing, concrete mix, and hardness. Cutting concrete too early causes raveling and cutting too late will cause uncontrolled cracking. 

operating a circular saw

As a general standard, in hot weather conditions, it’s safe to cut concrete at least four hours after pouring the concrete and 12 hours after in cool weather conditions.

It’s important to take note of this since cutting concrete blocks in the wrong time can lead to abrasion and wear and tear. Furthermore, avoid the following: 

  1. Using the wrong blade
  2. Pushing or exerting too much pressure
  3. Using a circular saw with a ben spindle
  4. Cutting at high speeds continuously 
For powerful circular saws, you can check my list of top-performing corded circular saw here

How Deep Should the Cuts Be?

The general rule of thumb to follow is 1/3 to ¼ of the slab’s thickness. So if you’re cutting an 4-inch concrete block, then about 1.3 to 2 inches deep. 

Now what to do about the remaining 2 inches? You can use a jackhammer to finish up the job. 

sawing concrete

The general rule of thumb to follow is 1/3 to ¼ of the slab’s thickness. So if you’re cutting an 4-inch concrete block, then about 1.3 to 2 inches deep. 

Now what to do about the remaining 2 inches? You can use a jackhammer to finish up the job. 

Other sources you can read: 

Conclusion

Now you know how to cut concrete blocks with a circular saw. With all the information you now have at hand, cutting concrete blocks doesn’t seem to be as daunting now, does it? If you have plans to try this at home, try watching a demonstration materials first for safety purposes like this one here.

If you are confused about when to use a circular saw or a miter saw, here is how I pitted circular and miter saw.

More helpful guides to check: 

Learning how to cut pavers 

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Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.

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