Stone Relics Research Articles

Water vapor condensation prevention and risk rating evaluation based on Yang Can’s tomb

Temperature and humidity variations in burial stone relics can easily cause water vapor condensation, which is an important factor leading to their deterioration. However, the water vapor condensation mechanism and the evaluation of risk ratings have always been difficult problems in the protection of cultural relics. In this study, the water vapor condensation mechanism in Yang Can's tomb was comprehensively investigated through on-site monitoring, indoor experiments and software simulations, on the basis of which a physical model of water vapor condensation in this tomb was established and a water vapor condensation risk rating assessment method was proposed. The proposed method considers the difference between the dew point and wall temperatures within the tomb (dew–wall temperature difference) and the duration of water vapor condensation, and corresponding preventive and control measures were formulated for different risk ratings. The study revealed that when the wall temperature of the chamber is lower than the dew point temperature, water vapor starts to condense. The larger the dew–wall temperature difference is, the greater the risk of condensation. In addition, specific water vapor condensation prevention and control measures were proposed for Yang Can's tomb, and the prevention and control effects were simulated. The simulation results showed that favorable prevention and control effects could be achieved, and the proposed measures could be applied in practice. This study holds notable significance for investigating the water vapor condensation mechanism and evaluating the risk ratings of burial stone relics and provides a theoretical basis and reference for water vapor condensation prevention and control in burial stone relics.

Characteristics of the Temperature and Humidity Variations of Burial-Type Stone Relics and a Fitting Model

Burial stone relics remain in a humid, semi-enclosed environment for long periods, and temperature and humidity variations can cause deterioration acceleration. Yang Can’s tomb was selected as the research object, and field monitoring and simulations were performed to investigate the characteristics of temperature and humidity variations, after which the simulation results were evaluated. The monitoring results showed that solar radiation, rainfall, wind speed, and depth of entry are important factors affecting the variation in the temperature and humidity of burial stone relics. The temperature outside the chamber is greatly affected by seasonal variations, while the humidity inside the chamber is influenced by seasonal variations, so appropriate measures should be implemented inside and outside the chamber during different seasons to alleviate deterioration. On the basis of the above analysis, a temperature and humidity model for the interior chamber of burial stone relics was established in COMSOL software 5.6, combined with a porous medium heat transfer model and computational fluid dynamics (CFD) model. The temperature and humidity inside the chamber can be calculated by the temperature and humidity outside the chamber. This study provides data support for hydrothermal, condensation and other related studies of burial stone relics.

Quaternary ammonium silane modified Nanolime for the consolidation and antifungal of stone relics

Cultural relics such as wall paintings and stone relics face a decrease in mechanical strength and contamination from microbial growth. Nanolime (NL), as an exceptional inorganic nanomaterial used in the consolidation of cultural heritages, has been investigated for more than two decades. However, it has limited antibacterial properties. Here, we opted for dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (DC5700) to modify the surface of NL particles, praparing an organic–inorganic hybrid nanomaterial (NL-DC5700) that provides long-lasting antifungal effects for stone samples without sacrificing its consolidation effect. Characterizations demonstrate that DC5700 grafts onto the surface of NL particles through the formation of covalent bonds via dehydration condensation between the siloxane of DC5700 and the hydroxyl of NL, forming an organic shell layer that uniformly wraps the NL particles. NL-DC5700 can endow stone samples with near superhydrophobicity (NL, 25.4° and NL-DC5700, 142.0°) and durable antifungal effects over 90 days, superior to those of pure NL. NL-DC5700 shows no unacceptable impact on the appearance, porosity, or microstructure of the stone specimens. Our work explores the antifungal effect of NL-based materials and provides fresh insights into the development of versatile conservation materials for stone relics.

A hyperspectral evaluation approach for quantifying salt-induced weathering of sandstone

Salt-induced weathering is a common phenomenon in stone relics, and its traditional artificial evaluation of severity is greatly affected by subjective consciousness and lacks systematic standards. Here, we propose a hyperspectral evaluation method for quantifying salt-induced weathering on sandstone surfaces in laboratory tests. Our novel approach consists of two parts: data acquisition of microscopic observations of sandstone in salt-induced weathering environments, and machine learning technology for a predictive model. We first obtain the microscopic morphology of sandstone surfaces by near-infrared hyperspectral imaging technique. Then, a salt-induced weathering reflectivity index is proposed according to analyses of spectral reflectance variation. Next, a principal components analysis-Kmeans (PCA-Kmeans) algorithm is applied to bridge the gaps between the salt-induced weathering degree and the associated hyperspectral images. Furthermore, machine learning technologies, such as Random Forest (RF), Support Vector Machine (SVM), Artificial Neural Network (ANN), and K-Nearest Neighbors (KNN), are trained for better evaluating the salt-induced weathering degree of sandstone. Tests demonstrate that the RF algorithm is feasible and active in weathering classification based on spectral data. The proposed evaluation approach is finally applied to the analysis of salt-induced weathering degree on Dazu Rock Carvings.

Multi-Analytical Characterization of Stone Relics from Meili Section of the Ancient Tea Horse Road in Yunnan, China

The stone relics in the Meili section of the ancient Tea Horse Road in Yunnan, China, are important for Sino-Tibetan cultural heritage. However, these relics were exposed to the risk of hydraulic erosion due to the construction of a hydroelectric power station, and thus protecting these relics is now imperative. Preliminary investigations and analyses of stone relics are crucial for their subsequent conservation and restoration. Thus, in this study, multi-analytical characterization including the microstructure, mineralogical characteristics, elements, and chemical compositions of the stone relics was conducted using optical microscopy (OM), scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), polarized light microscopy, x-ray diffraction (XRD), and attenuated total reflection-Fourier transform-infrared spectroscopy (ATR-FTIR). In addition, the contaminants and pigments on the surfaces of the stone relics were identified and analyzed by Raman spectroscopy. OM, SEM and Raman spectroscopy indicated that the surface contaminants mainly comprised of moss and soil dust, and some of the stone relics exhibited porosity and weathering. Polarized light microscopy revealed that the mineralogical morphology of stone samples mainly appeared as allotriomorphic, hypidiomorphic, and colloform structures. ATR-FTIR, and XRD confirmed that the stone relics mainly consisted of quartz, muscovite, illite, and chlorite. In addition, Raman spectroscopic analysis showed that the pigments on the relic surfaces included chalk, barium white, langite, green earth, amorphous carbon black, chrome red, and chrome yellow. The findings of this study may provide scientific support for the conservation of the stone relics.

Study on the Mechanical Properties and Durability of Hydraulic Lime Mortars Based on Limestone and Potassium Feldspar

Natural hydraulic lime (NHL) can be used as an inorganic cementitious material, as it exhibits low shrinkage, salt-alkali resistance, moderate strength, and good durability with cultural relics. There has been increasing interest in NHL, as it is considered an appropriate material for the restoration and reinforcement of architectural cultural relics. In this study, limestone and potassium feldspar were mixed and calcined at different ratios and high temperatures, and artificial hydraulic lime (HL) was produced. According to the X-ray diffraction (XRD) results, the resulting products after high-temperature calcination were mainly composed of calcium oxide, dicalcium silicate (C2S), and dicalcium aluminosilicate (C2AS). As a compromise, when potassium feldspar accounted for 30% of the total mass, HL contains a more suitable air-hardening component and hydraulic component. Scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS) analyses show that the phases of calcium carbonate (CaCO3) and hydrated calcium silicate (C-S-H) gradually increased with prolonged curing time for HL. To study the partial mechanical properties and durability of HL, a comparison was made with NHL. The mechanical properties were investigated with the flexural and compressive strengths and shrinkage. The results show that HL has higher strength than NHL, but NHL has smaller shrinkage. Accelerated aging tests indicated that HL and NHL5 led to higher resistance to water immersion, fluctuations in temperature and humidity, sulphate decay, an alkali environment, and frost–thaw action than NHL2. HL has excellent mechanical properties and durability and can be considered a conservation material for stone relics in the future.

Biological Disease Survey of Open Stone Relics in Ningbo Area

Biological Disease Survey of Open Stone Relics in Ningbo Area

Weathering Characteristics of White Marble Relics Around the Hall of Supreme Harmony (Taihe Dian) in the Forbidden City

Fangshan Hanbaiyu is a typical white marble in China that was mainly used in high-grade royal buildings represented by the Forbidden City. Over centuries of natural erosion, most marble artifacts have undergone a variety of deterioration. Based on the deterioration investigation of a total of 726 balusters, 559 dragon heads, and 698 frieze panels around the Hall of Supreme Harmony (Taihe Dian), nondestructive testing technology, including portable x-ray fluorescence, colorimeter, and surface hardness tester, were also used to evaluate the weathering degree and analyze the relationship between the deterioration patterns and the type and spatial distribution of marble components. The results show that the temperature difference stress caused by solar radiation and the erosion caused by rainwater are the main reasons for the weathering. This explains why the components facing the South and East are more deteriorated. In addition, an evaluation method for stone relics deterioration based on three indicators (surface integrity, surface color, and surface hardness) of stone relics was established, and the health index of 12 typical marble components was calculated by this method, the values showed a good linear correlation with the field survey, which can provide a useful reference for subsequent investigation and assessment of the deterioration of the marble relics.

Exfoliation of stone cultural relics under the microclimate in the Yongling Mausoleum of the Former Shu Dynasty

Many degradation processes of cultural heritage objects are associated with unsuitable microclimatic conditions. One of the most ubiquitous deteriorations is the crystallization of salts in pores, which can accelerate the erosion rate of masonry historical relics. In this study, the microclimate of the burial tomb and exfoliation of sandstone in the Yongling Mausoleum of the Former Shu Dynasty in Chengdu were monitored for 1 year to determine the development of the degradation. We established a connection between the monitoring data and exfoliation variations of the stone with time. To predict the deterioration of the stone, a three-dimensional computational finite element model was used to simulate the detailed process of the thermo-hygrometric performance that led to salt crystallization and artwork deterioration. Two results were obtained. In the simulation of the microclimate, the temperature ranged from 15 to 22.6 °C, and the relative humidity was heterogeneous and varied between 60 and 100%. The other was the relationship between the microclimate and exfoliation. It was found that the exfoliation was more severe in the higher relative humidity areas where the water vapor frequently interacted with the relics. The crystallization and hydration of sulfate produced stress, which damaged the stone relics. These results provide a rationale analysis and a reference for better management of the environmental interactions and reduction of the environmental impacts in the subsequent scientific conservation of ancient Chinese cultural relics in tombs.

Preparation of Poly(methyl methacrylate-co-butyl acrylate) Modified by Vinyltriethoxysilane and Its Properties for Stone Relics Protection

Preparation of Poly(methyl methacrylate-co-butyl acrylate) Modified by Vinyltriethoxysilane and Its Properties for Stone Relics Protection

Study of internal moisture condensation for the conservation of stone cultural heritage

The natural moisture condensation is considered an important decay factor for stone relics. If protection is only concerned with the conditions under which water forms on the surface, it can cause liquid water to form inside the stone relics over and over again. In this situation, it can lead to considerable damage to the stone relics in fact. In order to investigate the condensed water inside the stone relics, critical conditions have been calculated and a verification experiment has been conducted. The process of the moisture from a gaseous to a liquid state has been studied by several ways, such as the temperature and relative humidity analysis, the resistance and moisture analysis. The situation of both fresh and weathered sandstone samples is considered and analyzed. The results show that the liquid water was produced inside the stone relics before it was formed on the surface when the temperature and humidity gradient distribution from the rock surface to the inner rock is reduced. At last, this paper provides useful guidance to eliminate the harmful effects of the condensed water.

Polydopamine-Modified Nanolime with High Kinetic Stability in Water for the Consolidation of Stone Relics.

As a promising inorganic nanomaterial for the conservation of arenaceous sandstone-based relics such as wall painting, ancient building, stone heritage etc., nanolime (NL) has drawn increasing attention in recent years. Usually, NL needs to be dispersed into an alcoholic solution when applied. Nevertheless, a back-migration phenomenon of NL to the surface of the stone and delayed carbonation of NL enabled by alcohol do not guarantee good preservation effects. Dispersing NL into water can avoid the above issues. However, NL water suspension shows extremely poor kinetic stability, greatly restricting the penetration of NL into stone relics as well as bringing unfavorable impacts to the treated stone heritage. Here, we develop a facile method to synthesize polydopamine (PDA)-modified NL (PDA@NL). Characterizations demonstrate that PDA is uniformly distributed on the surface of NL particles though hydrogen bonds. In addition, the presence of PDA reduces the size of NL particles and achieves the highest specific surface area of NL reported to date. More importantly, water suspension of PDA@NL is far more stable than that of pure NL. The kinetic stability mechanism of PDA@NL in water is attributed to the lessened spatial interactions between NL particles, which is realized by the coverage of PDA on the surface of NL particles. Furthermore, the coverage of PDA does not inhibit carbonation. Within 105 h, NL in PDA@NL completes carbonation and obtains 93.7% calcite, which is comparable to that of NL suspension. Permeability tests prove that the PDA@NL suspension penetrates far deeper through stone specimens compared with the NL suspension. Additionally, PDA@NL presents good consolidation performances for stone samples. Our work opens a new direction for the modification of NL that will boost the studies of NL-modified materials as well as the conservation of cultural heritage.

Environmental Factor Accelerate the Deterioration of Tuff Stone Heritage: A Case Study of a Stone House in Southeast China

Water plays an important role in the deterioration of rocks. Often, the condensation cannot be ignored in addition to the rain and seepage, especially for stone relics built with tuff in humid areas. As part of this study, a century-old stone house in southeastern China was investigated alongside the microclimate, including temperature, humidity, and rainfall in the study area. Results showed that the main types of deterioration in this house were detachment, with some areas exhibiting surface hardness decreased by more than 50%. This decay was caused in part by condensation on the inner walls of the stone house during the rainy season. According to statistics, more than two-thirds of the time the rainy season produces condensate on the inner wall, which is primarily found on the north side of the house because there is less solar radiation. Conversely, the stress caused by severe temperature differences on the south side contributes more to the deterioration of rock. Environmental conditions with high humidity and strong temperature differences will accelerate the deterioration process of tuff stone with high porosity. Consequently, it is recommended that stones built by tuff in such a humid environment take rainproof measures and maintain good air circulation to reduce the adverse effects of condensation.

Conservation of surface gypsification stone relics using methanol solution of barium hydroxide as a novel treating agent

Conservation of surface gypsification stone relics using methanol solution of barium hydroxide as a novel treating agent

In-situ growth synthesis of nanolime/kaolin nanocomposite for strongly consolidating highly porous dinosaur fossil

Due to the excellent compatibility and ageing-resistantperformance, nanolime (NL) as a promising inorganic material is applied to consolidate aged sandstones and other arenaceous rocks based cultural heritage, such as wall paintings and stone relics. However, sometimes, NL does not assure a good consolidation strength for cultural relics. The existing researches on enhancing its consolidation strength are costly, time-consuming or still involving organic polymers. Here, utilizing inexpensive kaolin nanosheets as platform, we design and facilely synthesize a new nanolime/kaolin (N-K) nanocomposite by in-situ growth of Ca(OH)2 nanoparticles on the surface of kaolin nanosheets. The kinetic stability of this nanocomposite is comparable to the NL. Application experiment shows that the consolidation strength of the N-K nanocomposite in the highly porous pterosaur fossil (65%, porosity) is stronger than that of NL. The reason is due to the incorporation of kaolin nanosheets into the CaCO3 network after carbonation. For the first time, this work reports a new N-K inorganic nanocomposite and will facilitate the development of NL-based inorganic materials for the conservation of cultural heritage.

Mitigasi Bencana di Situs Cidanghyang, Pandeglang: Pencegahan Terhadap Potensi Kerusakan

The existence of the inscription is seen as the main indicator of Indonesia's entry into historical times. The seven Sanskrit inscriptions from Tarumanegara are written evidence of the establishment of a Hindu kingdom in western Java at the beginning of the fifth century AD under the rule of King Purnawarman. One of the inscribed stone relics known as the Munjul inscription, located far from the royal capital around the Citarum estuary between Jakarta and Bekasi, which testifies to the vastness of the territory and the influence of Tarumanegara rule. Carved on the top of andesite rock in situ at the Ci Danghyang meander, a tributary of the Ci Liman river that flows into the Sunda Strait, the Munjul inscription is in a vulnerable position to natural disasters, especially the unpredictable river overflows. Considering the importance of the Cidanghyang inscription as a cultural heritage that has been registered as RNCB 20161025 01 001351, this study aims to reveal the natural phenomenon resent condition that has the potential to change, damage, and even eliminate objects and the surrounding environment. By identifying the impact of river overflow in recent years, it is hoped that this research can obtain field information about potential direct and indirect threats to cultural heritage. The results of these observations can provide a rational basis for formulating disaster mitigation policies on the Ci Danghyang river which has a direct impact on the inscription site as a preventive step in the framework of a cultural resource management system.

A Novel Method of Preparing a Standard Weathered Sandstone Specimen: A Case Study of Red Sandstone from the Leshan Giant Buddha (Sichuan, China)

ABSTRACT In the laboratory study of the restoration and conservation of weathered stone relics, it is necessary to prepare standard weathered stone specimens for selection, effectiveness evaluation, and lifetime prediction of the conservation materials since the naturally weathered stone cannot meet testing requirements. This paper introduces a novel method of preparing the weathered sandstone specimen. Firstly, a systematic investigation was conducted on naturally weathered sandstone samples to obtain the essential information. The standard sand with the same particle size distribution as moderately weathered sandstone was selected as raw material. The influence of the types of cement materials, addition order of raw materials, number of hammering strikes during preparation, and the CO2–curing time on the physical properties (i.e., dry density, water absorption, total porosity, and compressive strength) was studied. Finally, the proposed method was proved to be effective, reproducible, and capable of inducing controllable microstructural, physical, and mechanical alterations by control of the variables in the preparation process to achieve an expected weathering degree. Moreover, the obtained specimens exhibited good precision in compressive strength values, and similar physical properties to the naturally weathered sample, so it is believed that the specimen could be used for the testing of conservation materials.

Spatial and temporal distributions of microbial diversity under natural conditions on the sandstone stelae of the Beishiku Temple in China

Climate and environmental conditions are the main driving factors that are responsible for the biological colonization and deterioration of stone heritage materials, especially for open-air sites. It is critical to determine the relationships among climate, microbial communities, and potential biodeterioration to conserve stone relics. In this study, samples were collected from two severely biodeteriorated stelae that are located in the open air at the Beishiku Temple, China. The genes of 16S/p23S rRNA targeting bacteria and algae and of the ITS1 region for fungi were analysed by using the Illumina MiSeq platform. Additionally, lichens were examined and described. The results showed that the bacterial community compositions varied with seasonal variations and that the dominant phyla were Actinobacteria, Cyanobacteria, and Proteobacteria. Most of the fungi were affiliated with Ascomycota, and some of them were lichenized types and were related to the lichens that had already formed on the stelae. Chlorophyta and Cyanobacteria were the dominant algal groups that inhabited the stelae surfaces. Xanthoria and Lecanora were the most dominant genera, which belong to foliose lichen and crust-like lichen, respectively. PCoA analysis showed that the bacterial and algal community structures, rather than those of fungi, were closely correlated with climate parameters. Temperature, precipitation, and wind speed were the main factors that were associated with changes in bacterial communities, while pH was closely associated with increased diversity of bacteria and algae. This study presents basic insights into the lithic microbial ecology in open-air stone monuments and may guide management decisions for their protection and preventative conservation.

Highly sensitive terahertz non\u2010destructive testing technology for stone relics deterioration prediction using SVM-based machine learning models

The hollowing deterioration of stone relics required effective non-destructive testing (NDT) methods for their timely restoration and maintenance. To this end, a new NDT method based on terahertz (THz) technology by using support vector machine (SVM)-based machine learning models was developed to assess and diagnose the hollowing deterioration of the Yungang Grottoes. According to experiment design, a series of hollowing deterioration samples with various thicknesses of hollowing deterioration were prepared and then measured by using THz time-domain spectroscopy (THz-TDS). Based on the THz-TDS results of 30 randomly selected samples, a SVM-based hollowing deterioration prediction model (SVM-HDPM) was established by analyzing the relationship between the hollowing samples and the THz spectral information. The reliability and accuracy of the model was further proved by verified and compared with using the THz spectral data of the remaining 10 samples. The experimental results with the linear kernel function greatly demonstrated that the SVM-HDPM can have superior prediction accuracy, implying that the model is feasible for the prediction the hollowing deterioration of the stone relics. Moreover, one data preprocess was introduced into SVM-HDPM to meet the needs of field-based test. The predicted results of five different hollowing deterioration with different flaked stone thickness revealed good performance with very low mean square error (MSE) value. Therefore, it is believed that the proposed method can be regarded as an effective NDT technique with practical applications in analyzing cultural relics and have promising future prospects in inspection stone relics-like ancient heritage for hidden flaws.

The Adverse Effects of TiO2 Photocatalycity on Paraloid B72 Hybrid Stone Relics Protective Coating Aging Behaviors under UV Irradiation.

The incorporation of photocatalytic nanomaterials into polymer coatings is used to protect stone relics from weathering. However, the photocatalytic nanomaterials might generate excess free radicals to degrade the polymer matrix. In this work, a certain amount of TiO2 nanoparticles were dispersed into Paraloid B72 and applied onto sandstone relics to explore the adverse effects of TiO2 nanoparticles on Paraloid B72 under ultraviolet (UV) irradiation. To fulfill this goal, the effects of TiO2 on pore formation and the structure of Paraloid B72 was studied by scanning electron microscopy (SEM). Moreover, the surface chemical composition, pore structure, surface roughness and surface wettability were explored via Fourier transform infrared (FTIR) spectroscopy, SEM, optical profilometer and water contact angle measurement under UV irradiation. Results showed that the incorporation of TiO2 nanoparticles prohibited the generation of pores in Paraloid B72 and there were no pores formed when the content of TiO2 exceeded 0.8 wt%. The water contact angle of origin Paraloid B72 and TiO2/Paraloid B72 decreased with the prolonging UV irradiation. Moreover, TiO2 nanoparticles were extracted from the matrix and the pores cannot be detected with the prolonging UV irradiation time under a higher content of TiO2. These research findings might promote the understanding of using photocatalytic nanomaterials in developing stone relics’ protective coating.