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  • Writer's pictureScarlett Lee

Rammed Earth + Fabric Formwork

Updated: Jul 6, 2021

When I travelled to Jeju island with my family, Suwolbong (수월봉) has left a great impression on me. Its stratification and exposed rocks were incredibly beautiful, and I felt, these geographical features were very much similar to rammed earth. Conventionally, rammed earthen walls were built as plain straight rectangular shapes, but I thought about how these beautiful curved forms can be also transferred to rammed earthen walls bringing advanced aesthetic quality and durability.

Impressive geographical features of Suwolbong (수월봉) at Jeju island, South Korea, Inspiration of rammed earth
Impressive geographical features of Suwolbong (수월봉) at Jeju island, South Korea

Since I have learnt fabric formwork at the University of Edinburgh, I was so much drawn to its flexibility, affordability, and great potential to design. Fabrics have a wide range of types and diverse properties. For example, according to the percentage of spandex on fabrics, the extent of elasticity is significantly different. This means that forms created by fabric formwork are limited only by designers’ imagination. Furthermore, fabrics are generally cheaper and lighter than wood, so that it is expected to bring a crucial contribution to reducing construction fees and times compared to traditional timber formwork.


I have created fabric formwork for a rammed earth model stabilised with lime and cement. One side of fabric formwork was made of a rigid synthetic fabric and wooden panels which confine the shape of the model. This stiff fabric was intentionally used in order to prevent the form was bulged out too much, and it was fastened securely to withstand the tension pressure of a cast.


The other sides of fabric formwork are created with polystyrene moulds and fabrics having a high percentage of spandex which is stretched adequately to catch the fine details of polystyrene moulds.

fabric formwork, rammed earth, earth architecture
The Description of fabric formwork and soil mixture
fabric formwork, rammed earth, earth architecture
The three sides of fabric formwork are supported with polystyrene moulds
fabric formwork, rammed earth, earth architecture
A completion of fabric formwork

Three types of mixtures were poured and rammed into the fabric formwork from bottom to top; sand and lime mixture, concrete mixture with plasticiser, and sand and lime mixture with plasticiser. The minimum amount of water was used, and several layers of coloured mixtures were added between.


fabric formwork, rammed earth, earth architecture
Fabric wrinkles were created during the process when earthen mixture was poured and rammed in the fabric formwork

After the formwork was dissembled, the elevation pressed against 4 wooden panels displayed an interesting fabriclike texture. Fabric wrinkles created between ridges of wooden panels were embedded on rammed earth. If it is examined more carefully, it is noticeable that even the delicate weaving pattern of the fabric was expressed on the façade. Furthermore, the middle and top layers which are mixed with plasticiser are less porous than the bottom layer so that weaving pattern of the fabric is more clearly visible.


fabric formwork, rammed earth, earth architecture

fabric formwork, rammed earth, earth architecture

On the other hand, the other 3 elevations had shapes controlled by polystyrene moulds. Despite big sizes of aggregates, fine details were relatively well expressed maintaining haptic textures.


fabric formwork, rammed earth, earth architecture

fabric formwork, rammed earth, earth architecture

It was very interesting to see that fabric formwork is successfully working on fabricating rammed earth. At the later stage, I would like to develop this technique further at a bigger scale of models.


I am very much interested in designing the façade of rammed earth not just because it is visually pleasing but also it enhances the resistance to the impact of rainwater and wind. For example, an aerodynamic shape of a rammed earth wall is more efficient on withstanding wind forces than a plain straight wall, and it also contributes to reducing the erosion caused by rainwater which is accelerated by prevailing wind force. Considering the fact that diverse designs of rammed earthen can be produced with fabric formwork, this technology will definitely bring a great benefit to increase the life span of rammed earth buildings minimising environmental loads.

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4 commenti


mathew
21 apr 2021

Very interesting, I noticed how the uneven wall can solve the problem of heavy erosion in the tropics.

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Scarlett Lee
Scarlett Lee
23 apr 2021
Risposta a

Thanks Mathew. Undulated rammed earth wall helps to reduce erosion slowing down the speed of rainwater running down on the surface.

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Scarlett Lee
Scarlett Lee
18 nov 2020

Hi Hab, many thanks for leaving your comments. I am very glad that you find my work interesting. I built the model a year ago in my uni lab, and sadly my architecture school lab has closed since March due to the pandemic. I cannot remember well the information of the plasticiser, but I played around with it to see the effect of it on rammed earth.


When it comes to the formwork, I set up horizontal wooden frames intentionally to create a stratification effect just like Suwolbong as shown at the first image. If you see the latest project of mine, the doghouse project, you can see that I built vertical timber scaffoldings to control the bulging of fabrics…


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hab keys
hab keys
16 nov 2020

really interesting method for rammed earth, what plasticizer are you using , what proportion ? using plasticizer seems smoothing surface nicely, but is sustainable mix plastizer ? i wonder ... , about frame , why not using vertical framing than horizontally, with large semi rigid fabric along the edge , to smoothing bulling or inprint ... i will follow your post carefully :) really nice and innovant work on rammed earth ( regards from france :) )

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