Adapted ageing tests for the evaluation of alabaster used in the restoration of Bishop’s Palace of Tarazona

Abstract

The advanced condition of deterioration of the column’s bases of the courtyard of the Bishop’s Palace of Tarazona (Spain) built in the middle of 16th century required its restoration with Aragonese alabaster. Thus, adapted ageing tests were developed to simulate the environmental conditions in which the stones were and will be exposed. These tests were thermal fatigue by temperature variations, acid rain and water stagna­tion by immersion tests and a combination of both agents of decay. The results indicated that alabaster did not experimented deformation after thermal fatigue but a progressive dehydration to bassanite. This process entailed an increase of porosity and consequently a loss of structural properties. The dissolution was measured as a lineal weight and volume loss while porosity and capillary uptake remained stable. The conclusions of this study establish the importance of restoration protocols to maintain the alabaster integrity when used and exposed to rainwater and insolation.

Investigating the Geoenvironmental and Climatic Impacts on the Facades of Historical Houses in Killit (Dereiçi) Village, Mardin

“…The impact of water on the stone has led to mass losses on the stone surface and mortar voids between the joints in the Savur region, resulting in the problem of 'missing part'. Several studies have highlighted the detrimental effects of water on limestone-based materials, including surface erosion, mortar voids, and missing parts (Alves et al, 2021;Ergüler & Shakoor, 2009;Bustamante et al, 2020;Iucolano et al, 2019;Beck & Al-Mukhtar, 2014;Bonazza et al, 2017;Gulotta et al, 2018).…”

“…Beck & Al-Mukhtar (2014) observed that there is a significant erosion in the limestone with wetting-drying cycles. Bustamante et al, (2020) found a mass loss of more than 14% on stone surfaces that are heavily exposed to water. Winkler (1997) observed that the side exposed to rain shows significant erosion in stone structures, while the material is preserved on the protected side.…”

Effects of Water on Natural Stone in the Built Environment—A Review

“…An example of significative mass redistribution was observed by Beck and Al-Mukhtar [67] with the formation by wetting-drying cycles of a calcite patine in limestone. Tests with alabaster (gypsum-rich material) performed by Bustamante et al [68] attained a mass loss slightly below 14% in conditions of immersion and shaking, using water with "natural" pH (i.e., the pH of water in equilibrium with atmospheric CO 2 without human contributions; pH = 5.6), which was prepared by mixing tap water (pH around 7) and distilled water (pH = 4.5). Visual observations in this last study showed some noticeable dissolution with clay-filled fissures developing a positive relief.…”

Deterioration analysis of historical village house structure in Mersin Kanlıdivane archaeological area by UAV method

“…Other situations in the literature caused by the effect of water were reported as mass loss problems in stones exposed to cycles simulating sunlight, evaporation, condensation [15][16][17][18][19][20][21][22][23]. Lubera [24] reported six stone types (fine-grained conglomerate, breccia, limestone, sandstone, amphibolite, and two granites) in the study, with the effect of water about 6% in breccia samples, 0.5% in limestone and 4% in fine-grained conglomerate samples.…”