| During a thousand years’degradation, the murals in Mogao Grottoes suffered from plenty of damages. The change of the microclimate and mural surroundings are the main factors to destroy the murals slowly and play key roles in the damages development. Hence, this research discussed mural damages development due to microclimate, main works and conclusions are shown below:1. The investigation on field on environment monitoring in Mogao Grottoes was carried out, including the area of the monitoring caves, date, locations of the sensors and so on. The blister and mural color change as the typical damages were analyzed in quantification. The data in this chapter provided the basis on the improvement of monitoring the microclimate, mural surroundings and simulating experiments in later works.2. According to the temperature and relative humidity data in history, the influences of the area of caves, floors and the location in the same floor on the temperature and relative humidity were analyzed. The smaller area and lower floor of the caves were, the more obviously changed of the relative humidity.The factor of the location in the same floor less affected the microclimate in the cave. The approach of grid division was utilized for collecting the temperature and relative humidity data and then the data was disposed with the software of Surfer 10.0 to acquire the distribution diagram of the temperature and relative humidity in the caves. At last, the method for the sensor locations in the cave was confirmed.3. The supporting layer, mural plaster and pigment were identified with integrated analytical methods, such as XRD, Raman spectroscopy. The results showed that the components of supporting layer and mural plaster were quartz, calcite and other minerals. The pigment mainly included minium, hematite, cinnabar, atacamite, lasurite, which are common mineral pigments on the ancient murals. The pH, conductivity, salt content and the types of soluble salt were analyzed. The results revealed that the mural plaster is neutral and the salt contents are about 1%-5%, which mainly concluded sulfate, sodium salt and chloride.4. The simulating experiments were carried out to measure the time when the moisture was through the different layers of mural in various relative humidity. It found that with the relative humidity increased, the speed of the moisture through the mural layers also increased. The time of moisture through the painted layer was about 9-19s, through the painted layer was about 35-53s and thorough the mural plaster layer (20mm) was about 88-218min. The results provided the reference when the frequency of the environment monitoring would be confirmed.5. The mural plaster with different contents of sulfate sodium were disposed in various freeze-thaw cycles, which indicated that the samples with 3% salt content were destroyed after one freeze-thaw cycle. The compressive strength of samples with no salt,1% and 2% salt contents decreased with the salt content increased. The simulating experiments of mural blister with different salt content and relative humidity were carried out. The results found that sodium chloride was the main factor on mural blister appearance. The diameter of mural blister increased with salt contents increased in various relative humidity environments. The samples with 15% water content and in 30% relative humidity, the mural blister appeared fastest in all relative humidity environments. The factors of mural disruption, such as salt/water ratios, drying and watering cycles, soil/sand ratios were analyzed in quantization with Matlab software approach. When the salt content was moderate and the soil/sand ratio was 3:1, the mural disruption developed fastest. Moreover, when the salt/water ratio was 2:10, the simulated mural disruption was similar with that on the mural in Mogao Grottoes and this ratio was also the key to control the water and soluble salt in the mural in the future. |
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