Flexible formwork is an appropriate construction method for optimised concrete geometries;
Low cost formwork system
Improve productivity through creation of multiple "one-off" elements - aim for mass-customisation
Permeable mould improves surface quality
Permeable mould improves durability
New possibilities for architectural design
Put structural material only where it is needed to minimise embodied energy in new building designs.
Fabric Formwork Society
In 2008, the International Society of Fabric Forming (ISOFF) was formed at the first international conference on flexible formwork held at the University of Manitoba, Canada. In 2012, the second conference was held at the University of Bath. In 2016, we joined forces with the International Association of Shell and Spatial Structures (IASS) to hold ISOFF track at the 2016 Symposium in Amsterdam. In 2017, a new Working Group of IASS was formed (WG21) led by Professor Arno Pronk and Dr John Orr which formally merged the two groups. The new Working Group is titled "Advanced Manufacturing and Materials" and has a remit much broader than just flexible formwork. Please see our website.
The use of fabric formwork for concrete structures can be traced back to the early 1900s, and the methods involved mainly stem from work in offshore and geotechnical engineering. In 1922 it was proposed by Johann Störe to use concrete filled fabric bags in the construction of underwater concrete structures. After his invention of ‘vacuum concrete’ in which vacuum pumps are used to remove excess water from freshly poured concrete, Karl Billner recognised the advantage of fabric formwork in allowing more water to be extracted from the concrete mix. His patent (from 07/07/36 and available online) shows a rather complex method by which water is extracted from the top surface of a flat slab.
It was not until the late 1960s that any real headway was made in this field, precipitated by the new availability of low cost, high strength, durable synthetic fibres that allowed complex shapes to be formed. A patent application in 1965 describes a method for the production of what are now known as concrete ‘mattresses’. These are formed using layers of material joined at regular intervals and pumped full of concrete. Hillen’s method was successful in both the Netherlands and the United States, and was quickly refined into what is now known as ‘filter point’ matressing (or lining). Later innovations include systems for pile jacketing and vertical formwork.
Initial interest in the architectural possibilities of fabric formwork (as opposed form finding, undertaken by Candela et al in the 1950s) can be attributed to the Spanish architect Miguel Fisac (b.1913, d.2006). In 1969 he completed the Centro de Rehabilitación para la Mutualidad del Papel (MUPAG) in Madrid, where he developed what would become the first patented method for pre-fabricated fabric formed wall panels.
In later years Flexible Formwork has been used widely, in both architectural and structural applications. Professor Mark West is widely regarded as the leader in this field and worked at the University of Manitoba, establishing the Centre for Architectural Structures and Technology (CAST). Professor West now works in North America and Europe.
Research at the University of Bath has focused on the structural design of optimised structures, and contributes to a growing body of knowledge in this field. World-leading work also continues under Professor Pedreschi (University of Edinburgh), Professor Block (ETH Zurich), amongst many others.
Additional information can be found in my PhD thesis:
And in this state of the art review, authored by PhD student Will Hawkins, along with members of COST Action TU1303:
Hawkins, W., Orr, J., Ibell, T., Shepherd, P., Michael, H., Kromoser, B., Michaelski, A., Pedreschi, R., Schipper, H. R., Veenendaal, D., Wansdronk, R. and West, M., 2016. Flexible formwork technologies: a state of the art review. Structural Concrete, 17 (6), pp. 911-935.
In 2012 the Second International Conference on Flexible Formwork (icff2012) was held at the University of Bath, chaired and organised by Dr Orr.
The full conference website including proceedings, videos, and workshop information can be found here