“Soil” is the most popular structural building material in the world building industry. However, concrete and steel has been used more in 20th and 21st century. As a result, chaotic non-characteristic world is spreading out, and regionality has been disappearing. Japan is originally rich in forest, and developed high recognition of wood culture over thousands of years. Now, Japan is facing the situation that the uses of imported wood are increasing compared to domestic timber due to the economical reason. At the same time, we are on the “century of environment”, cannot avoid researching environmental friendly material and structure. In order to resolve problems described above, we think “material not to be influenced by economy” and “environmental friendly material” are essential.
There, we focus our attention on a possibility of “New Soil Structure”. We resolve our goal with natural material “magnesium oxide”, and make “Soil Structure” with post-consumer material and strength clears the Japanese structural standard.
Natural Additive = Magnesium Oxide
We picked “magnesium Oxide” as a natural additive mix into soil. It is said it was used for masonry joint for pyramids and Great Wall in China. Its substances are extracted from ocean and land (magnesite mineral), so can be produced everywhere in the world and resourceful. Also, it is safe as it designated as food additive, and harmless enough to return to the ground.
Background and Direction of Earth Block Development
The Earth Block Project started in 2008, was developed together with Universities, corporate, and specialist. The concept is “Construction material that can be made with any soil in the world, is stronger than the existing soil construction material, and return to nature 100%”. For instance, sun baked blocks made of lime and animal manure used
in developing countries returns to nature 100%, but not very strong. Block made with cement for extended strength do not return to nature 100%. For both of these, soil used for the base must be examined. With our Earth Block, any clay-like soil in the world can be used, and including the additives, it is 100% natural. Its strength surpasses the Japanese Construction Standard which is the highest in the world. With the most advanced performance feature of this soil construction material, even houses made of sun baked block in developing countries with dangers of collapsing from disasters can be made safer, cheaper. Currently, 2,600 soil blocks are being manufactured for a single story resident building. All the work to create blocks, mixing the ingredient using soil at the construction site and land fill bound soil in the same prefecture, are done manually. 30 blocks that weighs 20 kilo each are being made by 4 to 6 volunteer staffs per day.
Materials Are Selected By The Keyword, “Density”
There is no structure category “Soil Structure” in the Japanese building code, and masonry is the only way to use soil as a structural material. There are couples of condition we need to clear to use soil. First, wall thickness must be thicker than 400mm. Second, you need to have a supportive wall within every 10m. Lastly, top beam needs to be concrete or steel.
There are a few new materials been used beside Earth Block walls. Those materials are selected based on the keyword, “Density”. Glass blocks which hold its ground against Earth blocks, LVL which is layers of veneer, and terrazzo floor. Even though each material has a strong characteristic, these are similar in density and it results in creating harmonious space.
site area : 184.62㎡
building area : 47.84㎡
total floor area : 41.39㎡
structure : Masonry – Earth Block
Architecture Design : Yasuhiro Yamashita+Masahiko Takada+Azusa Ishii+Ryo Takagi/Atelier TEKUTO
Structural Design : Jun Sato+Yuko Mihara/Jun Sato Structural Engineer
Mechanical Design : Kazuhiro Endo/EOS plus
Lighting Design : Sueko Kanaya/Visual Technologies
Experiment Supervision :Matsumura, Fujita Lab./University of Tokyo, Koshiishi Lab./Waseda University