To what extent is the fabric formed rammed earth wall eroded after 5 months?
Updated: Jul 6, 2021
The erosion of earthen walls is a natural process being affected by environmental factors especially rainfalls. Even concrete walls are eroded by rainfalls. Important questions lie in how to control the amount of erosion on the earthen walls and to what extent the erosion on the walls is tolerated. Normally, lime or concrete is used to stabilised earthen walls, but other than the chemical method, sustainable approach needs to be considered first. For instance, erosion checks such as bricks, ceramic tiles could be embedded in the rammed earth walls to slow down the speed of rainwater. This approach is not only functional but also aesthetic expressing naturally eroded and haptic texture of rammed earth walls. Also, according to a study, it turns out that the erosion of rammed earth walls occurs fast just after the completion, but it nearly stops after several years, not undermining the structural integrity.
I have observed a rammed earth doghouse several months since its completion. Since I finished Phase 1 construction in October 2020, the 30cm height doghouse was a perfect shelter for 5 newborn babies. They lived altogether there about 2 months until 4 of them are adopted, and now it is a home for my lovely dog Myeong-Rang (means ‘cheerful’ in Korean).
As the half-completed house has been covered by a temporary roof with waterproofing sheet over 5 months, as you can see in the image below, the wall near the entrance was more eroded expressing rough textures. If it is examined more closely, the bottom layer below a damp-proofing course has a darker colour than the top layer, and it becomes much darker when rain falls being damp, however, it has not been nearly eroded being stabilised with lime.
If you see the close-up image of the external surface of the wall, it is noticeable that the middle unstabilised layer reveals a rough texture as fine soil particles are washed away. Lime-stabilised bottom and top layers show a relatively similar condition as the 5-months-before state, except the fact that fine details such as seam lines are gone.
When I have looked into the internal surface of the rammed earth wall, I have found that the first layer has become smoother being touched by a dog consistently, on the other hand, the middle and top layers present relatively rougher texture.
The erosion of rammed earth walls is not something to be avoided but to be appreciated in advance in the design process. Therefore, the calculated erosion can be integrated as a design element as the rough and haptic texture of rammed earth walls is revealed over time expressing the intrinsic beauty of the material itself.