Greenbrae Chair

ONE: FORMING AND MIXING

Step 1 – Form Details

  • This form is open on one side, unlike a traditional concrete form that would need to be capped.
  • The fiber-reinforced concrete mix can be sprayed in the form and hand-packed to the full 1″ thickness.
  • The fiber-reinforced concrete mix can be sprayed in the form and hand-packed to the full 1″ thickness.
  • The tall wall on the left in these pictures is removed when the piece needs to be demolded.
  • Every time the form is re-assembled, it needs to be caulked to make it water-tight.

Step 2 – Form Construction

  • The casting surface is made from 3/4″ melamine-coated particle board.
  • The rest of the form is made from 3/4″ plywood, braced with 2×4’s, and assembled with drywall screws.

Step 3 – Prepare for Casting

  • After the form is assembled and sealed, clean it up with denatured alcohol.
  • Placing the forms on saw horses will elevate it and make spraying easier.
  • The form can be rotated or flipped depending on what surface is being sprayed or hand-packed.

Step 4 – Add Modifier

Step 5 – Add Concrete Mix

  • Add 1/2 bag of D-FRC or PreCast Mix.
  • Blend thoroughly, being sure to rotate the bucket, scrape down the sides, and make sure any unmixed material at the bottom is blended in.
  • Add the remaining 1/2 of the bagged mix and continue blending.

Step 6 – Scrape the Sides

  • Scrape down the sides and bottom of the bucket with a trowel.
  • Mix again until there is no unmixed material.

Step 7 – Check the Consistency of the Mix

  • 16 ounces of additional water can be added to the mix.
  • Use a wet mix if the material is going to be sprayed or cast.
  • Use a firmer mix if it is going to be hand-packed.
Next: Spraying Face MixGreenbrae Concrete Chair - Spraying and Casting | CHENG Concrete Exchange

Spray 1/8″ of face mix onto the form surface using either CHENG’s DFRC or Surecrete’s Xtreme precast system. The consistency of these mixes are ideal for this project.