Design Development

Salt Licks is a unique and innovative structure requiring the design, research and development of a new construction system, for a one-off application. In concept it is a 6m high structure formed of salt blocks – a canvas that sits on the Lincolnshire coast facing the sea that will weather and erode over time.

The controlled erosion of the blocks (rather than a collapse) was the defining objective leading to a uniquely fruitful collaboration with the engineers Structure Workshop and materials scientist Dr Andrea Hamilton of the University of Edinburgh (now at the University of Strathclyde), with specific expertise in the impact of salt on construction materials. The construction system developed has become an integral part of the understanding of the scheme, enriching and adding greater depth to the initial concept.

The design is simply formed of two walls with a staircase between which leads to a viewing platform. The walls are formed by an outer layer of salt blocks with an internal core of concrete to provide stability and literally hold the blocks in place – a variant form of full-fill cavity construction with a bond pattern providing a flush outer surface and a highly articulated inner face.

Once the salt has dissolved the concrete becomes apparent revealing an indexical imprint or memory, of the blocks that once existed. Over time this ‘waffle’ structure is expected to fill with sand and allow inhabitation of dune plants and local wildlife, taking on a further life cycle of its own.

The salt blocks used for this project are commercially manufactured for water-softening machines and as such can be seen as both multiples and pure minimalist objects in their own right. Refined from mined salt, the blocks are pure white in colour with a surface texture of marble. The fine crystal size allows them to be formed under pressure to within two decimal places of accuracy and with the density of engineering bricks.

The precision of the blocks allows for the use of a 2mm thin-bed mortar joint. The mortar itself has been the subject of extensive development in the search for a mix that would not dissolve more quickly than the adjacent blocks, nor conversely create a "bottom-of-walls" effect of a protruding mortar lattice. A salt-lime mortar was developed to provide the builder with a mix of familiar character and laying properties.

A 'mass-concrete' solution has been adopted to mitigate against the deleterious effect of a highly saline environment on reinforcement with stainless steel reinforcement bars used selectively for slabs, stairs and lintel openings only.

A number of sample panels have been constructed both in controlled conditions and on site in Lincolnshire. Each has helped to further define and refine the final construction system adopted.

Although the interest and the pleasure of Salt Licks is that the form and textures the structure will take on is not known, it has been possible to explore the realm of possible visual effects through a series of sculptures using individual salt blocks as material.

Salt | Water (after Serra), subjects salt blocks to verbs (or actions) such as drip, spray, splash and soak, using water as the sculpting tool. The dissolution of salt and subsequent recrystalisation reveals unexpected forms and ongoing growth beyond the initial sculpting.