Damage Characteristics of Sandstone Subjected to Coupled Effect of Freezing‐Thawing Cycles and Acid Environment

Abstract

In order to figure out the damage characteristics and mechanisms of sandstone under coupled effect of acid erosion and recurrent freezing-thawing cycles, sulfuric acid is chosen as acid solution, and sandstone, representative stone in Sichuan province, is chosen as a sample to conduct the freezing-thawing cycling test. In the meantime, chemical component of the solution is also tested and recorded in the progress of freezing-thawing cycling. Then, the nuclear magnetic resonance (NMR) test and magnetic resonance images (MRI) test on samples are conducted with the help of the AniMR-150 NMR imaging system. After a series of tests, the sample’s appearance, dry mass, porosity, T2 spectrum, solution’s pH, solution’s metallic ion concentration, and magnetic resonance images are obtained and analyzed. The results show that dry mass loss and porosity grow with F-T cycles increase and pH value decrease. Montmorillonite, illite, and clay in sandstone react with sulfuric acid solution; as a consequence, K+, Mg2+, Fe3+, and Al3+ separate out, and the solution’s pH and concentration of K+, Mg2+, Fe3+, and Al3+ increase with F-T cycles. Acid erosion and F-T cycling lead to the generation of new micropores and expansion of micropores at the beginning; when the acid solution is exhausted, new micropores generate under the effect of freezing-thawing cycling, and micropores in samples keep developing and expanding with the increase of freezing-thawing cycles. Coupled effect of acid corrosion and recurrent freezing-thawing cycling causes much more serious deterioration to sandstone samples than acid corrosion.

Experimental Study on Physicomechanical Properties of Deep Sandstone by Coupling of Dry‐Wet Cycles and Acidic Environment

“…e inherent properties of rock are changed due to the specimen has been immersed in different solutions for 5 days (stage I). erefore, the values of m and F of the soaked specimen are calculated according to formulas (16) and (17), as shown in Table 6. According to the constitutive model (19), the uniaxial mechanical parameters of sandstone are calculated and compared with the test values.…”

“…With the advancement of research, the testing range of mechanical parameters extends to tensile strength [12], shear properties [13,14], and fracture characteristics [15]. With the development of microtechnology and the leap of detection technology, scanning electron microscopy (SEM) [16], nuclear magnetic resonance (NMR) [17], computed tomography (CT) [17], and acoustic emission (AE) [18] technologies are now often used to study the microchanges of rocks under dry-wet cycles.…”

Rock Features and Alteration of Stone Materials Used for the Built Environment: A Review of Recent Publications on Ageing Tests

“…Experiments with burying in guano, which can have saline and acid effects, have described reactivity of lithologies with calcium phases in limestone and basalt [9]. According to Deng et al [36], clay minerals can react with acid solutions, enhancing the microporosity and susceptibility to freeze-thaw of sandstones.…”

NMR Experimental Study on Dynamic Process of Pore Structure and Damage Mechanism of Sandstones with Different Grain Sizes under Acid Erosion

“…Miao et al [9] performed uniaxial and triaxial compression tests and splitting tests on granite samples after acid solution erosion at different pH values and flow rates. Deng et al [10] studied the damage characteristics and mechanisms of sandstones subjected to acid erosion and repeated freeze-thaw cycles. Fang et al [11] studied the combined effects of chemical erosion and freeze-thaw cycles on the compressive failure characteristics of yellow sandstones.…”

“…SEM can describe rock micropore structures but can only test a relatively small extent of the rock surface and so cannot provide overall pore structure information nor dynamically observe changes in pore structure. Use of CT can provide a complete threedimensional view of rock samples but can only be used for real-time observations and cannot determine the characteristics of the rock microstructure [10] and is uneconomical [30]. NMR is a nondestructive testing technique.…”