Step 4: Mixing GFRC (Pre-Blended)
The main advantage of GFRC is that the pieces can be much thinner without losing strength. It can also be applied with a range of techniques, unlike regular wet-cast concrete. It can be sprayed through a texture hopper, packed into a form by hand, or wet-cast as usual. Because you're using less material, the formwork doesn't need to be as heavily reinforced. Another advantage of GFRC is that pieces can be demolded in 12 hours or less.
GFRC is mixed using a mortar mixer or a paddle mixer, instead of a traditional concrete mixer. Small batches under 30 lbs. can still be mixed by hand.
- Rubber Gloves
- Particle Mask
- 17 gallon mixing bucket
- Paddle Mixer
Dual paddle, on a stand (this is a luxury). You can also use a 1/2" drill motor and a paddle, but a proper dual paddle mixer will work better, especially for something very stiff like the fibrous backing blend.
Size of bucket:
8 gallon = 50 lbs.
17 gallon = 100 lbs.
25 gallon = 150 lbs.
1. Add liquids to the bucket first. Then blend in pigment, whether it's wet or dry.
2. Add 1/2 of the total batch of the DRY components.
3. Thoroughly mix with the paddle mixer, moving the paddles around the bucket, and scraping the walls with a trowel.
4. Add 1/2 of the remaining dry mix.
5. Thoroughly mix again.
6. Add the rest of the dry material.
7. tempering the mix: the art
8. if it's too dry, add water