ShapeCrete makes it easier to build larger scale concrete projects. You don't need specialized equipment like drum mixers, concrete vibrators, or spray guns. The form building is cheaper and less complex because the forms don't need to be so robust. The best part is that you can press it into the form like a GFRC mix, but you don't need to create your own mix designs or use expensive chemical modifiers.
Fu-Tung Cheng, the founder of ShapeCrete, designed this hostess station for Green Zone Restaurant in Los Angeles. It uses about 300 lbs. of ShapeCrete, mixed in smaller batches and hand packed into a simple 3/4" laminate form. With just a few helping hands the form was packed in just over an hour.
This Instructable will highlight the basics of the project - building the form, decorative details, mixing, demolding, slurry and polishing.
Materials + Supplies:
- 3/4" High Gloss Laminate Form
- Fiberglass Mesh
- Basalt Rebar
- Silicone Caulk
- 2x4 Tip Jig
- 300 lbs. ShapeCrete
- Portabella SmartColor Pigment
- Table Saw
- Corded Drill and Mixing Paddle
- Diamond Hand Sanding Pads
Size: 5' x 4' x 18"
Technique: Hand Packed
Step 1: Forming
The form is built out of high gloss laminate. It's approximately 4' x 5' x 18" deep and open on the end where it meets the wall. The edge of the form has a 1" lip to help maintain an even thickness when the piece is packed with ShapeCrete.
The form walls are cut on the table saw and screwed together with 1-1/2" drywall screws.
A high gloss surface like this will give the finished piece an extremely smooth finish.
Step 2: Tilting Frame
A simple jig built from 2x4s is used to help rotate the form as each individual wall is packed.
This is basically a platform with a kickstand.
Step 3: Form Details
The interior of the form is detailed with rubber stamps and knockouts, fossil inlays, and embedded minerals. Each detail adds interest to the piece and plays off the decor of the space.
Rubber molds are stuck in the form with spray adhesive or silicone. The long rubber mat will give the piece texture in that area, and the disc shaped knockout will form a concave depression in the top of the piece. A foam knockout is placed in the corner and will create a ledge for a piece of Florite to be glued in place.
The final detail is an ammonite fossil that will be embedded in the top surface of the hostess stand. It's held in place with silicone caulk.
Step 4: Mixing
The piece was cast from approximately 300 lbs. of ShapeCrete. Each 50 lb. batch was mixed using a paddle mixer on a corded drill, and each batch is pigmented with Portabella pigment from the CHENG SmartColor line.
Mixing smaller batches can be done with a cordless drill and a mixing attachment, but for anything over 20-30 lbs. it's better to use a strong 1/2" corded drill.
The mixing is done in 5-gallon buckets.
Step 5: Pack the Form
The largest side of the form is packed first. The mix is pressed into the edges of the form, making sure there are no large air pockets. As one section is packed, fiberglass mesh is troweled into the surface.
Step 6: Reinforcement
Additional reinforcement in the form of Basalt Rebar is added in an X across the largest side.
More fiberglass mesh is troweled into the back side and then it's time to tilt the form and begin packing the other walls.
Basalt rebar is sweet stuff. A 2 or 3mm rod has the equivalent strength of #3 rebar. For thinner projects this is perfect because you won't get ghosting in the surface. Even better, it won't rust over time.
Step 7: Tilt and Pack
To help keep the mix from sliding down when the form is tilted, a 3/4" piece of plywood is laid on the back side. Then the top of the form is packed, and finally the remaining wall.
The whole thing is covered with painter's plastic to keep moisture inside while it cures.
Step 8: Demold
After the piece has cured for 4-5 days the form can be removed. The form walls are stripped and then the tilting jig is tipped down and the piece is lifted off the form.
Step 9: Slurry and Polish
The voids and holes on the top surface are filled with slurry and then lightly polished with a variable speed concrete polisher.
Step 10: The Finished Piece
The hostess station is directly in front of the door and provides a place for patrons to be greeted as they enter the restaurant. The subdued color is in contrast to the bright green wall accents and the natural veined texture complements the hand troweled plaster walls.
This is just one example of a project using ShapeCrete on a larger scale. Follow along for more concrete projects!