Water Repellency of Monument Soil Treated by Tung Oil

Earthen monuments exposed at archeological sites are afflicted by a series of diseases, such as shrinkage, cracking, and collapse, related to moisture evaporation or partially soaked in ground water. Water repellency treatment is a promising improvement to the durability of earthen monuments. To understand the hydrophobic mechanism of the soil treated by Tung oil, geotechnical tests, including permeability test and water repellency test, in the laboratory were conducted on clay soil sampled from a site where Da Bao’en Temple was in Nanjing, China. Test results indicate that Tung oil film coated on the soil particles could well decrease the surface tension and free energy, providing waterproofing property without obvious change in esthetic appearance. Laboratory tests indicate that Tung oil treatment decreases the hydraulic conductivity and increases the water repellency of the soil. Water repellent treatment with Tung oil provides a new approach for earthen monument conservation under humid weather condition.