Degradation of rammed earth under wind-driven rain: The case of Fujian Tulou, China

Abstract

In the history of human civilization, rammed earth has been used over thousand years to construct infrastructure, such as buildings, shelters, and defense structures. The structural integrity of rammed earth infrastructure can be affected by many factors over time. Abundant rainfall and typhoon can strike the World Heritage site of Fujian Tulou due to its unique geographic location in the southeast costal line of China. The effect of wind-driven rainfall on durability of rammed earth materials taken from three demolished Tulou sites with different construction history is studied. Laboratory element tests are conducted to identify that both the unconfined compressive strength and shear strength are inversely proportional to the water content. In drip tests, the maximum degree of erosion is obtained, when the rain direction falls within the range of 30–45°. In rain simulation tests, the peak erosion depth is measured for the case with a rain direction of 15–30°. Essentially, higher degree of erosion is resulted when the initial water content is higher, and lower degree of erosion is obtained when the clay content is higher.