EXISTING TECHNOLOGY: FABRIC FORMED CONCRETE
Fabric Formed Concrete is a remarkably economic and efficient method of forming concrete. Fabric forming takes advantage of the flexibility of fabric produce supple, complex catenary surfaces that are both structurally intelligent and materially efficient. Plywood is a critical part of fabric formwork, providing the compressive strength to hold the load of the poured concrete. The plywood is arranged in a frame and has the shape profile removed from the plywood material. The plywood forms a sandwich, with two pieces of polypropylene canvas in between. The concrete is poured, the material is hand-vibrated, and the formwork remains in place until the concrete has cured. The formwork and fabric are removed and both can be reused with another pour. Fabric formed concrete has typically been thought of as a form-finding technique, where the physical properties of the concrete and fabric would create an optimized solution for the profile given.
LIMITATION: BRANCHING CURVATURE
While fabric formed concrete is remarkable in it’s ability to produce complex surfaces, it is fairly limited when those complex surfaces are compounded. A compound complex curvature creates bunching within the fabric, which creates both an unsightly and structurally questionable result.
OPPORTUNITY: SUBDIVIDED MESHES
Subdivided meshes are meshes that have been “smoothed” to represent the complexity of their curvature within their organization. If the topology that is being flattened is smoothed through the subdivision process, the result will be an optimized template for producing that surface out of a flat sheet of fabric. Once the surface has been optimized for the tensile forces of the forming process, unrolled into a flattened plane, the flattened surface can become a template for cutting the canvas. The cut canvas can be manually stitched to become an optimized surface, ready to take the load of the concrete without bunching. This limitation is a major reason why the use of fabric formed concrete has not become more widespread. While complex curvatures can produce essential vertical members that could support enclosing elements, it is necessary for those surfaces to be compounded to become enclosing elements themselves. It is in this area where the concept of fabric forming as a form-finding exercise was interrogated.
This technique does not completely work. While the mesh subdivision process does decrease the amount of folding and bunching within the fabric, it does not eliminate it entirely. A more accurate process for positioning the fabric within the mold needs to be developed in order to completely eliminate wrinkles. While an optimized fabric can accommodate one set of complex curvatures, it cannot describe significant changes to that curvature or multiple sets of curves like ripples or waves. Other areas worth investigating are joinery between multiple fabric formed pieces, production processes that produce identical copies of similar forms, and material composition to decrease weight. Regardless of these shortcomings, fabric forming remains a remarkably cost-effective process, produces remarkably supple curvature and enables a unique tactile quality to the concrete. The process of leveraging mesh subdivision algorithms to optimize the curvature for single sets of complex curvature does seem to have merit, it is the process of manufacturing the formwork that needs to be refined.