Old as the hills: traditional building materials in the 21st century
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Old as the hills: traditional building materials in the 21st century

15 Aug 2012

Materials such as straw, clay and rammed earth have been pushed out of the mainstream by 21st century concrete and steel, but these materials are still a viable option for eco-conscious builds. Chris Lo explores the modern use of these ancient building blocks, and asks if they can still play a significant role in an increasingly high-tech industry.

Old as the hills: traditional building materials in the 21st century

Materials such as rammed earth need to be constituted and applied properly to be effective

Looking at most modern, developed cities, it’s easy to understand the myriad ways in which the construction industry has changed during the last century, not least in the materials it uses.

"It’s easy to ignore the ancient building blocks that are as old as the hills, and in many cases, a product of them."

Most of today’s urban skylines are dominated by the hard lines of concrete and steel, softened by sleek glass facades that, with today’s know-how, can wrap around entire skyscrapers. The Shard, the latest addition to London’s silhouette, became the most recent representative of this ultra-modern urban design trend when it opened last month to the appropriately high-tech accompaniment of celebratory lasers streaking through the night sky.

With all this focus on the lustrous achievements of modern architecture’s cutting edge, it’s easy to ignore the ancient building blocks that are as old as the hills, and in many cases, a product of them. Materials such as straw, clay and rammed earth are clearly far less sophisticated than those employed today, but the endurance of countless ancient structures stands as tangible proof of their longevity if used correctly.

It’s clear that traditional materials still hold a place in the 21st century construction landscape, even if that place has been gradually relocated from the mainstream to the peripheries. In this feature, we take a look at the benefits and challenges going against the grain with traditional materials.

Lessons from history: ancient materials in the 21st century

From an environmental perspective (a perspective that all of today’s architects and construction managers must keep in mind), these ancient building blocks hold significant advantages over their modern successors. A 2008 cross-university study of materials used in traditional Turkish buildings emphasised the environmental advantages of old-school construction materials.

"Natural building materials have now become unfamiliar – local expertise is shrinking into a small niche or disappearing altogether."

"Materials being obtained from totally natural, local and renewable resources have source-efficient and energy-efficient features," the study found. "They have significant ecological characteristics since they are easily recyclable and re-usable, utilize agricultural wastes and do not produce any wastes."

In the 21st century, the vast majority of traditional building materials are used in various regions of the developing world where financial and logistical restraints make age-old construction methods the only viable option. In developed countries, the use of most of these materials has declined significantly.

According to the June 2012 Clay Building Materials and Clay Refractories Market Report, for example, the use of clay is expected to continue to decline in the face of more modern competition. The report does predict, however, that the global market for clay building materials will grow to around $52.2bn by 2017, primarily driven by "rising infrastructure and industrial activity in emerging markets in the Asia-Pacific region".

Rammed earth and more: re-learning traditional techniques

One of the main stumbling blocks to any kind of traditional construction resurgence is an inevitable consequence of the construction industry’s steady technological progress – with the industry speaking a language of concrete and composites, steel and glass, natural building materials have now become unfamiliar. Local expertise is shrinking into a small niche or disappearing altogether.

"The perception of straw, perhaps influenced by its poor performance withstanding the huffing and puffing of the Big Bad Wolf, is that it is unstable and risky."

Materials such as rammed earth need to be constituted and applied properly to be effective, so any further uptake of these materials will require a greater focus on re-learning these vanishing skills.

All the environmental and thermal advantages of rammed earth haven’t stopped some poorly conceived and executed rammed earth building projects from turning into unmitigated disasters. A 2004 project to use rammed earth for a Southwark Primary Care Trust nursery complex in the UK literally fell to pieces as a poor understanding of the material led to horrendous problems, including rain damage, poor compaction and severe distortion during drying.

"The project engineers had become so concerned about the apparent lack of structural stability in these unstabilised earth walls that they insisted sections were removed so that steel columns could be inserted to carry the load of the floors above," said Earth Structures, the rammed earth specialist that was brought in to help rectify the damage. The project eventually abandoned rammed earth for more conventional masonry.

Worst-case scenarios like this conflict with the material’s success stories, like the Eden Project, an ecological attraction in Cornwall that used rammed earth for two 45m walls; the exposed walls have had no slumping or weathering problems in the 15 years since their construction. The recently completed Sheppard Lecture Theatre at the Wales Institute for Sustainable Education (WISE), meanwhile, incorporates the UK’s tallest rammed earth walls at 7.2 metres. The unstabilised walls are exposed, proving that the material can withstand environmental pressures with considered design and thoughtful detailing.

A 2011 report by Joel Audefroy, senior lecturer at the Instituto Politécnico Nacional of Mexico, shed new light on the need to retain traditional construction knowledge in light of the devastating earthquake in Haiti in 2010. Rebuilders were quick to blame "vernacular structures" and traditional materials for failing to withstand the quake, but Audefroy argues that it is the loss of knowledge, not traditional materials, that made Port-au-Prince so vulnerable to seismicity.

"Several studies in seismic regions have revealed that many so-called vernacular structures have demonstrated highly acceptable behaviours during earthquakes as a result of traditional construction systems developed over the course of long periods of time," Audefroy writes. "Yet despite this, the majority of these structures have become more vulnerable due to various factors, including a gradual loss of local traditional knowledge."

High-tech straw: mixing the old and the new

Another essential method of increasing the use of traditional materials in the modern age is adapting them for modern use. Increasingly, designers, contractors and manufacturers are realising that the environmental benefits of traditional materials can be combined with modern standards if today’s technology is used to optimise material performance.

Straw has been in use as a building material for thousands of years, but its application in modern construction has been relegated to alternative green builds that are looking to make a point by using it. The perception of straw, perhaps influenced by its poor performance withstanding the huffing and puffing of the Big Bad Wolf, is that it is unstable and risky.

But with modern methods, straw has proved itself as resilient as many modern competitors. For its CAFboard, Straw specialist Stramit processes straw bales through a high-tech conveyor, which pulls them apart and reconstitutes them, under intense heat and pressure, into rigid, construction-quality boards. The heat and pressure releases lignin, the straw’s natural binding agent, meaning that no adhesives are needed. The end result is a volatile organic compound (VOC)-free material that is nearly fireproof and exhibits excellent sound mitigation.

As for stability, the BaleHaus at Bath University, a structure built from prefabricated panels infilled with ModCell straw bales, was completed in 2009 as a test of the material’s properties. The house was recently subjected to the equivalent of hurricane-force conditions, and moved a maximum of four millimetres under peak loads, well within the project’s design requirements. Big Bad Wolf, eat your heart out.

"We hope the data we’re collecting on the BaleHaus will help strengthen the case for the mainstream building industry switching to using more sustainable building materials like straw," said Bath University’s BRE Centre for Innovative Construction Materials director, Professor Pete Walker.

There are undoubtedly major challenges that need to be overcome if traditional, sustainable building materials are to retake any of the mainstream ground they have lost during the last few decades. But as experience has proven, by refamiliarising the industry with half-forgotten skills, as well as optimising traditional building blocks using modern technology, many of these materials are more than up to the task of presenting a slightly more rugged and much more eco-friendly alternative to the 21st century’s concrete consensus.


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