The aesthetic of waste

Materials World magazine
,
1 May 2010
Cladding brick

David Binns and Dr Alasdair Bremner, researchers from the University of Central Lancashire, Preston, UK, examine the potential of mineral waste as an alternative to traditional construction materials.

The demand for new buildings and related architectural materials is placing unsustainable demands on mineral resources. Simultaneously, higher standards of living are creating ever greater amounts of waste material that end life as landfill. Whilst the arguments for embedding sustainability throughout the construction industry are well established in the minds of architects and designers, this often conflicts with their hunger for materials that offer new aesthetic properties. It is therefore becoming increasingly important that alternative products are developed that offer a new aesthetic, whilst being less reliant on virgin raw materials.

This issue is being addressed through a research project funded by the Arts and Humanities Research Council (AHRC), involving the development of a novel material endowed with properties that could offer a viable sustainable alternative to conventional facing bricks, clay tiles and imported quarried dimension stone such as granite or marble. Quarried dimension stone, unless sourced locally, is often unsustainable. Stone extraction impacts on the environment, often resulting in severe damage to ecological habitats in the mine area, whilst importing huge volumes of stone incurs high levels of embodied energy. Using a mineral waste streams, such as existing quarry and stone finishing waste, together with industrial waste, this product would alleviate reliance on high volumes of virgin stone.

The initial research at the University of Central Lancashire (UCLAN), Preston, UK, involved introducing small amounts of recyclate into conventional clay forming processes. It became apparent that more waste material could be added, to the point where the waste element had become the dominant component, creating a material containing 100% reconstituted waste. Testing has shown the new material not only has unique aesthetic qualities, but is durable, with functional properties that allow application in a variety of architectural contexts, such as cladding sheets, facing bricks, tiling systems and work-surfaces.

The process involves sintering materials such as recycled container glass, waste from the tableware and sanitary-ware industries, steel smelting, coal fired power stations and ash from incinerated domestic waste. In the UK only 33% (approximately 460,000t) of manufactured glass is recycled, the majority of which becomes low value products, such as drainage backfill, shot-blasting abrasive or fibre-glass. The material could provide a high value application for waste container glass. Furthermore, the low temperature sintering process avoids any toxic, synthetic polymers, common to many current composite products.

Knowing its place

Materials have philosophically and historically engendered a strong association with ‘place’. Traditionally, most construction materials were sourced locally to the construction site, meaning minimal transport cost or environmental impact. Mineral waste such as damaged stone or masonry from demolished buildings could be sourced on-site or close by, forming up to 50% of the total material within the composite. Using local mineral waste would promote a meaningful visual and philosophical connection between materiality and place, whilst also resolving the embodied energy related drawbacks of imported materials. Colour and texture can be engineered to a clients specific requirements, to blend or contrast with existing materials, fine or course in texture or embedded with larger decorative fragments of mineral waste. The ability to form the material in a variety of bespoke shapes, during the initial making process, or through machining, post production, further enhances the creative potential for architects and designers.

Recyclability

The UCLAN work has shown that any second-quality casts or waste trimmings and sludges from machining may be directly returned into the production process, avoiding manufacturing waste, and satisfying ‘closed-loop’ manufacturing. Through testing, the composite has displayed a lifecycle similar to existing construction materials such as common brick. If dismantling was necessary, the product can be re-used or easily recycled – through re-introduction into the original manufacturing cycle as a raw material. Whilst transportation of waste to point of manufacture, processing and return to site will incur energy consumption, the embodied energy is predicted to be significantly lower than imported stone.

Made from 100% recycled waste, creating zero production waste, being totally recyclable itself and offering unique aesthetic properties, the material has considerable eco-credentials and may offer a real and sustainable alternative to conventional building materials.

Further information:
David Binns

As the AHRC funded project nears conclusion, researchers are developing prototype products to be displayed at 100% Design to be held at Earls Court in London, UK, from 23-26 September.