Evaluation of Salt-Induced Damage to Aged Wood of Historical Wooden Buildings

Abstract

Salt is a common cause of damage to building materials used in cultural and historical buildings. The damage to aged wood in historical wooden buildings has not been extensively studied, resulting in the need for a more detailed analysis. In this work, Yingxian Wooden Pagoda, a typical historical wooden structure, was taken as the research object. Multichemical analyses were conducted to evaluate and understand the salt-induced damage to the aged wood using a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer, sulphur K-edge X-ray absorption near-edge structure spectroscopy, X-ray fluorescence spectroscopy, X-ray powder diffraction, and attenuated total reflectance fourier transformed infrared spectroscopy. The results showed the presence of invasive salt crystallisations and ions in the aged samples. The source of these invasive elements was deduced by identifying the type, amount, and valency of the elements; they were found to be derived from environmental factors such as acid rain and atmospheric pollutant. The unique damage mechanism and route induced by salt in historical buildings made of wood were summarised; the damage was attributed to the accumulation of sulphate salt causing hydrolysis of the carbohydrates and salt crystallisation resulting in mechanical damage. This interdisciplinary study is significant for decision making in studies related to the preservation and evaluation of historical wooden buildings.

Alkaline Delignification of Tropical Hardwoods: A promising Approach for Sustainable Material Development

“…Chemical degradation weakens wood by breaking down its structural components, which reduces its mechanical properties. Another relevant factor that can affect the mechanical properties is foreign inorganic components (such as sulfur, calcium, sodium, and chlorine), which can cause hydrolysis of some carbohydrates and the formation of minerals crystals resulting in mechanical changes (Mi et al 2020). According to the ash composition results Andiroba, Sande, and Choiba signi cantly increased their inorganic elements (Table 2).…”

“…Accumulation of minerals can deform tracheid and ray cells and burst wood cell walls due to macroscopic swelling, which affects the mechanical performance of wood (Mi et al 2020), thus chemical pretreatment with mineral accumulation alters the properties of deligni ed wood. The non-uniform impregnation of the center and ends of the wood with the NaOH/Na 2 SO 3 aqueous solution explains the differences in sodium content distribution between Sande, Andiroba, and Choiba hardwoods.…”

“…Mineral impregnation of wood cell walls, involving uptake of ions and water at the molecular level, can cause mechanical damage through the accumulation of crystallizing ions. (Mi et al 2020).…”

Deterioration of Microstructures and Properties in Ancient Architectural Wood from Yingxian Wooden Pagoda (1056 AD) during Natural Aging

“…Wood, a natural and organic biomaterial, has been extensively utilized in human life for thousands of years in various applications, including in tools, furniture, vehicles, weapons, and architecture [1][2][3][4]. Ancient timber constructions, as architectural wooden artifacts, are of exceptional historical, cultural, anthropological, economic, artistic, archaeological, and scientific value [2,[4][5][6][7].…”

“…Ancient timber constructions, as architectural wooden artifacts, are of exceptional historical, cultural, anthropological, economic, artistic, archaeological, and scientific value [2,[4][5][6][7]. The Yingxian Wooden Pagoda (1056 AD), located in Shanxi province, China, is a particularly remarkable example, as it is the oldest and highest extant pure-wooden structure in the world, with a height of 67.58 m (Figure 1a) [3,5,8]. It has attracted extensive attention and research due to the mystery of standing for a millennium [3,[8][9][10][11][12].…”