Prefabrication experiments - 41- Collapsible Core by Hal Hayes

The use of concrete for walls and floors is well suited for multi-unit housing. Its acoustic mass and inherent fire resistance protects each unit while providing a coherent load bearing system. Thermally and structurally concrete mimics stone’s mass and durability. However, concrete’s weight can be a constraint as it implies a massive vertical distribution of load as each floor’s weight adds to the overall load. In industrialized building systems, weight has often been regarded as a negative as it implies greater transport costs that often offset production gains. Furthermore, the repetitive nature of the industrialized process is not conducive to variations of form and concrete panel systems are often deemed inflexible. For these reasons concrete, even as a largely industrialized production, has retained a substantial segment of in-situ construction.

Taking the factory on-site has allowed for variety in shapes and forms and has been optimized to generate surprising and efficient results in terms of timelines and costs. Industrialized formwork is largely responsible for this optimization. The formwork, whether in wood, steel or plastics makes the assembly of walls simple and as intelligible as stacking building blocks in differing sizes, grids, and geometries. The necessary curing of concrete is and will remain a timeline restriction, as concrete components cured in a factory will be quicker to assemble on-site as opposed to their in-situ poured counterparts. From the invention of concrete, experiments in resizable, reusable, and adaptable forms have sought to optimize on-site construction and illustrate its flexibility.

The collapsible form invented by Hal Hayes and patented under the Econocrete brand was one such invention that brought flexibility, adaptability and a consideration of concrete’s weight to reusable forms for concrete construction.  The foldable articulated structure held panels in place as the concrete was poured and compacted. The form was collapsed or folded onto itself then removed and repositioned to continue work. Although it harboured a certain complexity in its manipulation, the system used similar concepts to today’s concrete block walls as the cellular core augments thermal and acoustic value. The open cellular structure also optimized the bearing capacity to weight ratio as the cellular structure perfected distribution of load bearing matter. Concrete as a housing material remains largely dependant on this type of optimized form to result process. 

Patent drawing for collapsible core US2244017