Our clients are becoming more aware of the need for low-carbon designs. This means that there will be an increasing focus on the use of biogenic (natural) materials within structural engineering.
This suggested reading list is a must for any engineer who wants to know more about earth and straw. James has also put together a suggested reading list on the use of timber and bamboo
with David Trujillo.
Earth as a structural material
Earth is an ancient material. Dug from the ground and compacted into layers, it can create a beautiful rustic environment. Earth’s sustainability comes from the way that it affects the internal air quality and its low embodied energy. If we avoid stabilisers such as cement, it can also be put back into the ground at the end of use.
However, if we are unable to use site won material and start importing it, its carbon footprint goes up. If we add stabilisers it goes up further and can no longer be put back into the ground.
We therefore need a good understanding of the available earth on site and its suitability for structural purposes. As engineers we shouldn’t just choose to build from rammed earth, we should let the site guide us.
Recommended reading on earth
JAQUIN PJ. And AUGARDE C. (2011) Earth Building: History, Science and Conservation. BRE
This book covers the restoration and repair of historic rammed earth structures. It is a very useful guide if you are working on refurbishment projects but may be less useful for design and detail of new buildings. It is worth noting that rammed earth can be scoured by water. Because of this you may want to consider providing details to the client on maintaining and repairing earth structures.
KING B. (1996) Buildings of Earth and Straw, Green Building Press
Bruce King writes funny and philosophical guides to design unlike anything else out there. I would highly recommend his book for that reason alone. However, for rammed earth he approaches it as low grade concrete, which is less helpful for unstabilised rammed earth. Print copy available for loan by post or in person to IStructE members.
Codes of practice
Australia, New Zealand and India all have codes of practice that cover the use of rammed earth. The Australian codes are currently being updated and are due for release mid-2021.