“Baihuimian” and Organic-Tempered Daub Floor——Scientific Research on Composite Building Materials of Neolithic Age in Xitou Site
WANG Xi-man1,2,3，YANG Fu-wei1,2,3，LIU Yan1,2,3*，LI Ting1,2,3，XIAN Yi-heng1,2,3，ZHANG Kun1,2,3，TANG Li-ya1,2,3，CHEN Xin-nan1,2,3
1. China-Central Asia “the Belt and Road” Joint Laboratory on Human and Environment Research，Xi’an 710127，China
2. Key Laboratory of Cultural Heritage Research and Conservation，Xi’an 710127，China
3. School of Culture Heritage，Northwest University，Xi’an 710127，China
Abstract：Xitou Site, located in Xunyi County, Xianyang City, Shaanxi Province, is a site containing rich human cultural relics from the Neolithic Age to the Ming and Qing Dynasties. In the excavation sites of Shangxitou Village and Nantou Village, many cave dwelling sites of Neolithic Age were found, and the floor of some of these sites was a Composite building material of “Baihuimian”(Lime layer) and organic-tempered daub, which were relatively well preserved. In this paper, stereoscopic microscope, polarizing microscope, ultra-depth of field microscope and scanning electron microscope(SEM) were used to observe the structure of “Baihuimian and organic-tempered daub” floor. In order to further solve the problems of sample production materials, production process analysis and technical principle, the means of X-ray Diffractometer(XRD), Fourier transform infrared spectrometer(FT-IR), thermal analysis(TGA-DSC), energy dispersive spectrometer (EDS) were used to analyze and detect “Baihuimian”, organic-tempered daub and “Baihuimian and organic-tempered daub” floor. The results showed that the main ingredients of “Baihuimian” are silica dioxide and calcium carbonate obtained by carbonization of loess-doll after calcination; The “Baihuimian” has three layers, which should be smeared for three times, and the thickness of each layer of “Baihuimian” is basically the same and not more than 1 mm; The substrate of “Baihuimian” is organic-tempered daub, in which the straw fiber can strengthen and inhibit cracking. When daubing the “Baihuimian”, the lime water infiltrated into organic-tempered daub and calcium hydroxide itself carbonated to produce calcium carbonate, which contributed to the stability and strength of organic-tempered daub structure. The two building materials are still closely combined, with only 10~20 μm distance between them, which indicates that at least in the late Neolithic Age, Chinese ancestors had widely mastered the compound building material and its construction technology. This study is of great significance to understand the understanding and utilization of natural materials by ancient Chinese ancestors and to sort out the development of traditional architectural science and technology civilization.
Key words：Neolithic Age；Xunyi Xitou site；“Baihuimian”；Organic-tempered daub；Composite building material
