After the 2014 Ludian earthquake in Yunnan, most of the traditional rammed-earth buildings in Guangming Village were severely damaged. During reconstruction, most villagers turned instead to brick-and-concrete houses. But the price of conventional building materials soared after the disaster, placing a heavy financial burden on families.
By improving the seismic performance and indoor environment of traditional rammed-earth construction, the project offered villagers a rebuilding option that is safe, comfortable, affordable, and ecologically sustainable — one they could carry out themselves and pass on.
The team designed and built a house for an elderly couple who had lost their home in the earthquake. As a demonstration farmhouse, the project tested the improved seismic rammed-earth building system in practice, together with a full upgrade of the building’s indoor environmental quality.
On a tight site, the design adopted a compact layout around a semi-outdoor courtyard with good daylight and ventilation. To keep the interior comfortable through the cold winter, the house uses double-glazed windows and added roof insulation.
To improve seismic performance, the project adjusted the proportions of clay, sand, and fiber in the earth mix and added a very small amount of cement, greatly increasing the strength and integrity of the walls. Vertical steel bars and horizontal concrete ring beams tie the structure together and prevent vertical cracking; the ring beams are concealed on the inner face of the earth walls to keep the facade intact. The project also used high-performance, easy-to-operate formwork and tools for rammed-earth construction. Shaking-table tests showed that the two-story improved rammed-earth building fully meets the requirements for seismic intensity 8 fortification.
The project followed the principle of “local techniques, local materials, local builders.” Its results fall into three areas. Environmentally, earth sourced on site needs no long-distance transport or deep processing, and passive design provides good daylight, ventilation, and thermal comfort — keeping the building’s life-cycle energy use and environmental load to a minimum.
Economically, both construction and running costs stay within what villagers can afford. The techniques and tools are simple to learn and use: once villagers master them during reconstruction, they can maintain their houses, carry the building craft forward, and gain a trade to make a living by.
Socially, local villagers took part in the whole reconstruction process. The team drew on resources from several universities across different disciplines, with active support from the local government. By modestly improving a traditional building technique, the project kept the buildings safe and sound, protected a building tradition that is both historic and ecological, and sustained the rural way of life that has grown up with it.
In the next phase, this improved seismic rammed-earth system will be used in more villages across southwest China. The reconstruction strategy — scientific and systematic — will also inform national and regional policies on post-disaster reconstruction and codes for rammed-earth construction.
