This Instructable will cover three ways to mix regular concrete, one way to mix glass-fiber-reinforced-concrete (GFRC), and instructions on performing a Slump Test to check the consistency of the concrete mix.

The method you use will depend mostly on the size of your project, but also on what tools and equipment are available. For a larger project, like a concrete countertop, you'll have to rent a mixer. For something smaller, the concrete can be mixed in a wheelbarrow. For even smaller projects, under 30 lbs., mixing by hand in a big bucket is perfectly fine.

  • Sacked Concrete Mix
  • Pigment, Water Reducer, CHENG Pro-Formula or other all-in-one Admixture (optional)
  • Concrete Mixer (there is a wide range of mixers out there)
  • Buckets
  • Water
  • Particle Mask
  • Thick Rubber Gloves
  • Trowel
In General:
  • Calculate the amount of concrete you'll need using a little bit of math or online volume calculators (don't subtract for knockouts).
  • Always mix up more concrete than you think you'll need.
  • Don't use sacked concrete that has been exposed to moisture and is hard like a rock.
  • Always throw out any big clumps in the mix that won't break up when squeezed in your hand.
  • If the mix is getting too stiff, agitating it with vibration will help it become fluid again.

Step 1: Mixing concrete by hand

For smaller projects, 30 lbs. or less, mixing the concrete by hand is pretty easy. It can be mixed in a 5 gallon bucket, a wash tub, or on a plastic sheet or a tarp. When you're getting your hands in the mix like this, be sure to wear thick gloves. Concrete is caustic and thinner gloves will rip too easily. It helps to have a hand trowel or a small shovel to scrape the sides and bottom of the bucket.

  • THICK Rubber Gloves
  • Particle Mask
  • 5 - 8 Gallon Bucket / Wash Tub / Similar
  • Trowel
  • Bucket / Clean Water
Paddle Mixer Attachment (optional):
Using a 1/2" corded or cordless drill with a paddle mixer attachment is one way to mix the dry material. After the water is added, the concrete will be more difficult to mix, unless you have a very powerful drill.

1. Weigh out all of the DRY material and add it to a bucket (Sacked Concrete Mix, Dry Pigment, Dry Water Reducer, Fiber, or any all-in-one Admixture like CHENG Pro-Formula).
2. Blend the dry material together until it's a uniform color. Always wear a dust mask when mixing dry concrete.
3. Break apart any clumps of concrete or toss them out if they won't break apart.
4. Measure out 3/4 of the recommended water and mix. If you're using liquid pigment or liquid water reducer, pre-blend it in this water.
5. Add the water to the dry material and mix. Scrape the sides and bottom of the bucket as you go, making sure you don't leave any dry material.
6. Add the remaining water gradually as needed until the mix is a workable consistency. If the mix is too stiff, you may need to add a little bit of water. There should be no dry pockets at this point. Mix thoroughly before casting.

Clean out the mixing bucket with water. Don't pour it down the drain because it contains active cement and it will clog the drain.

<p>When mixing larger jobs, how do you dry mix once the concrete mixer already mixed wet concrete?</p>
Very detailed and easy to understand about the batch of concrete. Thank you!
Nice, thanks for this.
Really helpful. Thanks to share.
I've read your countertop book. It's not a project I'll probably ever tackle, but it was extremely interesting, as was this instructable. Thanks for sharing more of your knowledge.
wow thats some great instructable right there, thanks for the share!
thats a really helpful share a banch of thanx

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