This Instructable will demonstrate how to make a rubber mold for casting a bent concrete table. It will cover making a cardboard mockup, producing the positive, casting a rubber mold, and finally casting the finished concrete piece using a fiber-reinforced mix and bending it to shape.
This project was completed during the 3 day Advanced Fiber Reinforced Concrete Training
at CHENG Concrete in Berkeley, California with guest instructor Chris Franzen from Surecrete. The unique characteristics of a fiber-reinforced concrete mix make it possible to cast a flat piece, wait until it enters a "false-set," and then bend the piece. For this we need a flexible mold, and in this Instructable we'll outline the steps needed to create a polyurethane rubber mold that will work for this technique.
Even if you aren't using a fiber-reinforced concrete system and bending concrete, the rubber mold-making steps are general enough to apply to any casting project.
Be sure to enter the Concrete & Casting Contest
for a chance to win some nice prizes!General Materials and Supplies: