Moisturizing an analogous earthen site by ultrasonic water atomization within Han Yangling Museum, China

Abstract

Dry cracking and salt enrichment are common deterioration of earthen sites being exposed to soil‒air coupled environments. The deterioration of earthen sites cannot be completely prevented by simply maintaining a high relative humidity (RH) of air environment, especially in the absence of supplemental liquid water, because of one-way migration of moisture from earthen sites to air environment. In the current work, a protection strategy of constructing a mist atmosphere over the surface of earthen sites, of which near-saturated air with micron-sized moisture droplets by an ultrasonic water atomization, was proposed to enhance the back diffusion of liquid moisture into earthen sites, and thereby inhibit the deterioration of earthen sites. The experimental moisturizing system with an ultrasonic atomization unit was built in an analogous earthen site exhibition hall in the field of Han Yangling Museum of Xi'an City, China. A series of tests were conducted to evaluate the feasibility and safety of the moisturizing system for earthen sites. The results showed that the moisture content of earthen site topsoil after moisturizing can be recovered to a level close to that prior to excavation of earthen sites, and the fractures once occurring on the surface of earthen site was effectively inhibited; The soluble salt content of earthen site topsoil was significantly reduced, and no salt damage occurred. It is anticipated that this study has a great potential for application to resist the one-way migration of moisture from earthen sites to air environment, and the salt damage and fracture of earthen sites.