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Ancient building technique may help future designs to be more eco-friendly

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June 4, 2009

Walls made from rammed earth may hold the key to more eco-friendly housing design in the f...

Walls made from rammed earth may hold the key to more eco-friendly housing design in the future

June 5, 2009 Every child learns early on that moist sand is the key to building a sturdy sandcastle. Now researchers at Durham University have studied this principle so it can be better applied to an ancient eco-friendly building technique of using rammed earth.

Rammed earth is a manufactured building material made up of sand, gravel and clay, which are moistened and compacted between two forms – or molds – where the mixture is allowed to set as a wall.

It was developed in ancient China about 2,000 BC, but it has been enjoying a resurgence in popularity as a sustainable building method in recent years, as it reduces the need for lumber and the forms holding the rammed earth in place can be reused.

The researchers, led by experts at Durham's School of Engineering found that the strength of rammed earth was heavily dependent on its water content. They also found that rammed earth walls, in a suitable climate, dried without losing all their water. The small amount of water that remained provided considerable strength over time.

The team believes that further study will help reduce the reliance on cement in building materials, which is responsible for 5 percent of man-made carbon output, and in doing so, cut carbon emissions. The environmental impact of rammed earth is further minimized since rammed earth materials are commonly sourced locally, which means it doesn't need to be transported long distances.

According to the researchers, their work may help the future design of buildings using rammed earth, and as the link between strength and water content becomes clearer, conserve ancient rammed earth buildings by putting methods in place to protect them against too much water entering a structure, which weakens rather than strengthens it.

The research from the Durham University team was published in Geotechnique.

Darren Quick

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
8 Comments

This is called "taipa-de-pilão" here in Brazil. There are many houses built with rammed earth here, and they last for hundreds of years with low maintenance. I participated in the building of a house using a different technique used by southamerican indians and tried out some other. Unfortunatly, people don't use this anymore and keep on living in shacks when they could have a healthy environment to live in. I'm intending to build a house with various techniques to demonstrate this to less fortunate people and teach them to build their own houses with very low cost.

For example, a finishing can be made with newspaper dissolved in water and mixed with clay in a almost liquid solution. Applying it many times creates a good finishing for interiors, for exterior walls it must be made waterproof. I used this to build a wood stove and it worked very well. For the inside of the stove I used a mixture of wood ashes and clay in the same manner. This creates a fireproof finishing that reflects the heat, improving the efficiency of the stove. It is not very strong, but it's maintenance is easy. Other building material involve straw, horse manure, and so on. We should use such materials, they are green, carbon neutral and won't contaminate the environment. And, best of all, they can be found anywhere.

walther.grube
5th June, 2009 @ 02:48 pm PDT

I at one time thought it would be nice to build a partially-subturanian house like this but condemned the idea because of one small concern, earthquakes. I have not heard any mention anywhere on how such a building would perform under tremors. My guess is not nearly as well as a concrete block wall with rebar reinforcement.

Matt Fletcher
6th June, 2009 @ 08:17 am PDT

There is no reason why re enforcement techniques using steel can't be used with rammed earth.

Also geometric design could be employed which would create an extremely strong structure.

Not only that but walls could be pre made on site, and then erected using modular design...

Un re enforced concrete is also subject to earthquake damage. That is why all concrete structures have steel re enforcing.

Having said that, we are at risk of being buried in various forms of plastic which could be utilised for dwelling structures.

As my grandmother always used to say, "where do you think away is? You can't throw something away, you throw it somewhere else."

We are fast running out of the "somewhere else".

Benjamin Ryan
19th June, 2009 @ 01:08 am PDT

rammed earth doesn't have very good insulation, and requires additional insulation for severe climates. It does have thermal mass however.

William Blackburn
29th June, 2009 @ 07:06 pm PDT

Mud houses in rural areas especially in Rajasthan(India) keep the inside house cooler in summer and hot in winter. In Zimbabwe a multi storied building was built on the design of ANT HILL without airconditioning. Ancient Domed structure offer coolness in summer. We can learn and adopt ancient architecture.

Dr.A.Jagadeesh Nellore(AP),India

Anumakonda Jagadeesh
7th April, 2010 @ 08:56 pm PDT

If you use rammed earth as a "in-fill", in other words, built up around a post-supported roof, and still reinforce it, the danger from earthquakes goes way down. The problem as I see it is that "modern" societies frown on or discourage this type construction due to the perceived value. Banks won't loan against it and governments find it hard to tax such structures. They want "modern" stick-built, conventional buildings that comply with the established codes. It is true that advocates of alternate construction techniques are making inroads but are the exception, not the rule. I personally think that any construction technology that is found to be fairly safe and allows the owner to self-build to keep costs down and to outright own the structure much sooner is a good thing!!!

Will, the tink
11th November, 2010 @ 10:53 pm PST

The Mother Earth News magazine was all over rammed earth in the 70's and 80's. Their experimenters used things like slip forms which were pulled up as the walls rose and they also mixed some cement into the earth to improve strength and water resistance.

Facebook User
15th November, 2010 @ 05:39 pm PST

In Thailand, it isn't for less fortunate people but for people who have eco-friendly heart.

McCane Chaisatien
15th July, 2012 @ 06:34 am PDT
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