Quantitative evaluation of weathering degree through Fuzzy-AHP method and petrophysics analysis for sandstone carvings

The assessment of weathering degree of sandstone carvings plays an important role in scientific conservation. However, the current state of weathering assessment research cannot meet the needs of scientific evaluation. The Jurassic sandstones used in this study were selected, and soluble salt and acid simulation experiments were performed on standard samples. Non-destructive methods are used to determine the weight, surface hardness, ultrasonic velocity, and water absorption. Furthermore, mineral composition and petrophysical properties are analyzed in the laboratory on small specimens. It is revealed that the main mineral, such as quartz and feldspar, is shown by oblate and prolate in shape. The moisture content of rock samples has a significant impact on their compressive strength. The deterioration process increases the porosity of the rock. As the number of cycles increases, so does the quality, surface hardness, and ultrasonic velocity. Water absorption coefficient, on the other hand, increases over cycles. In addition, the Fuzzy-AHP method is adopted to further evaluate degree of weathering on experiment samples. The macroscopic results show that the weathering degree is 0.3271 for sodium sulfate solution, indicating moderate weathering; 0.1951 for pH = 1 sulfuric acid and 0.1060 for pH = 2 sulfuric acid, showed low weathering; and 0.0516 for pH = 3 sulfuric acid and 0.0421 for pH = 4 sulfuric acid, inferring very low weathering.