To study the degree of strength parameter deterioration (DSPD) of Lushi swelling rock in the high slope area under wetting-drying cycles, 114 samples are remodeled. Wetting-drying cycle and triaxial tests are conducted to comprehensively analyze the influence of dry density, wetting-drying cycle path, and number of wetting-drying cycles on the strength deterioration characteristics of Lushi swelling rock. Using the fitting analysis and function superposition methods, the DSPD model of Lushi swelling rock under wetting-drying cycles is established, which considers the previous four influencing factors. The influence of the DSPD of Lushi swelling rock on the stability of high slopes under rainfall seepage and circulation conditions is studied. Lushi swelling rock exhibits significant strength deterioration characteristics under wetting-drying cycles. The overall DSPD for cohesion is higher than that of the internal friction angle. Under rainstorm conditions, strength deterioration leads to a shallower depth of the critical slip surface of the slope and a smaller safety factor. After eight rounds of rainfall seepage and circulation, the safety factor gradually decreases by approximately 14%-28%. This study provides and verifies the DSPD model of Lushi swelling rock under wetting-drying cycles, and the results could provide a basis for disaster prediction and the optimization design of swelling rock slopes.

This study investigates salt weathering in the indoor, humid environment of China's Jinsha earthen site. Methods such as digital microscope, scanning electron microscopy (SEM), ion chromatography (IC), energy dispersive spectroscopy (EDS), and laser particle size analysis were employed to collect and analyze samples from four heavily weathered walls. The sampling approach took into account differences in depth and height and prioritized the extraction from various weathering layers to unveil the attributes, causes, and mechanisms of salt weathering. The findings indicate that the Jinsha site's eastern segment suffered salt-induced damage, such as powdering, salt crusts, and blistering, due to the presence of gypsum and magnesium sulfate. These salts were primarily sourced from groundwater. Groundwater ions ascended to the site's surface via capillary action, instigating various forms of salt damage. Salt damage severity has a direct link to salt and moisture content. The degradation patterns can be categorized into powder and multi-layered composite deterioration, both seems related to soil particle composition. Powder deterioration tends to occur when the sand content exceeds 40%. This research proposes preservation strategies that focus on managing groundwater and conducting environmental surveillance. These measures are designed to effectively address and mitigate the risks associated with salt damage.

Weathered granite soil (WGS) is highly water-sensitive and widely distributed across southern China, where the region's rainy climate contributes to geological hazards such as collapsing erosion, landslides, and ground subsidence. This study aims to elucidate the impact of this rainy climate on the deterioration of WGS by investigating the suffosion characteristics of granite residual soil (GRS) and completely weathered granite (CWG) at various stages of weathering. The research explores how suffosion affects their mechanical properties and microstructural features. A series of suffosion tests were conducted under controlled water pressure, followed by one-dimensional consolidation tests, cyclic triaxial tests, scanning electron microscopy, X-ray diffraction, and X-ray fluorescence analyses to analyze the deterioration mechanisms at both macro- and micro-scales. The results show that suffosion leads to the loss of fine particles and overall settlement of the soil samples. Microscopically, Mica is almost entirely lost, iron cementation is disrupted, and clay minerals, along with quartz and feldspar debris, are eroded, causing microstructural damage. The loss of minerals at the micro-scale exacerbates the formation of pores and cracks, increasing WGS porosity and promoting the progression of suffosion. On the macro-scale, suffosion alters the physical properties of WGS, with fine particle migration and loss leading to soil skeleton deformation, reduced stiffness, and decreased compressibility. Furthermore, a suffosion index is proposed, correlating microstructural changes with macroscopic mechanical parameters. This study has practical and theoretical significance for slope stability, collapsing erosion prevention, and surface subsidence mitigation in WGS in southern China.

In recent years, the application of green, low-carbon geopolymer cementitious materials in engineering construction has increased. However, the winter freezes and spring thaws in northwest China often result in structural deterioration. To investigate the freeze-thaw (F-T) resistance and microstructure change of the solidified soil with steel slag-fly ash geopolymer (SF-GP), a series of mechanical and microscopic tests were conducted under the condition of F-T cycle. The objective of these tests was to systematically analyze the F-T resistance and disintegration changes of geopolymer-solidified loess after undergoing F-T cycles. The results indicated that the deterioration degree of the solidified soil would increase as the number of F-T cycles increased; yet, the addition of SF-GP could effectively reduce the deterioration degree of the solidified soil. After seven F-T cycles, the unconfined compressive strength and cohesion value of samples with geopolymer additions of 0%, 10%, and 20% decreased by 23.4%, 16.5%, and 12.0%, respectively, and 51.0%, 42.6%, and 42.1%, respectively. After 15 cycles, the reductions were 34.0%, 21.7%, and 25.3%, respectively, and 83.4%, 67.3%, and 67.1%, respectively. The incorporation of SF-GP effectively reduced both the disintegration rate and the total amount of disintegration, which increased with the number of F-T cycles. The mechanical properties of the solidified soil were analyzed from a microscopic perspective and the change of physical image, allowing a deterioration prediction model between the mechanical properties of the solidified soil, number of F-T cycles, and amount of SF-GP to be established. Overall, the study findings can serve as a foundation and theoretical guideline for studies on the deterioration of geopolymer-solidified soil in cold regions as well as practical engineering applications.

Research on the performance of solidified soil in capillary water absorption seawater environments is necessary to reveal the durability under conditions such as above seawater level in coastal zones. Taking soda residue-ground granulated blast furnace slag-carbide slag (SR-GGBS-CS) and cement as marine soil solidifiers, the deterioration characteristics of solidified soil resulting from capillary seawater absorption were elucidated systematically through a series of tests including capillary water absorption, unconfined compressive strength, swelling, local strain, and crystallization. The microscopic mechanism was analysed through nuclear magnetic resonance and X-ray diffraction tests. The results showed that cement-solidified soil exhibited higher water absorption and faster swelling compared with SR-GGBS-CS solidified soil in the one-dimensional seawater absorption state. In the three-dimensional seawater absorption state, solidified soil with low GGBS dosage experienced a significant transition from vertical shrinkage to swelling during the capillary water absorption process, leading to a substantial decrease in strength after 7 days of crystallization. Cement-solidified soil displayed non-uniform and anisotropic swelling, along with the formation of more external salt crystals. Overall, the soil solidified with 25% SR, 10% GGBS, and 4% CS demonstrated robust resistance to capillary absorption deterioration in a seawater environment due to its minimal water absorption and swelling, uniform surface strain, weak salt crystallization, and limited strength deterioration caused by capillary water absorption.

Ground granulated blast furnace slag (GGBS), calcium carbide slag (CS), and phosphogypsum (PG) were combined in a mass ratio of 60:30:10 (abbreviated as GCP) to solidify dredged sludge (DS) with high water content. The long-term strength characteristics of solidified DS under varying curing agent dosage and initial water contents, as well as its durability under complex environmental conditions, were investigated via a series of mechanical and microstructural tests. The superior performance of GCP-solidified DS (SDS-G) in terms of strength and durability was demonstrated in comparison to solidified DS using ordinary Portland cement (SDS-O). The results indicated that the unconfined compressive strength (UCS) of SDS-G was approximately 3.0-4.5 times greater than that of SDS-O at the same dosage and curing ages, exhibiting a consistent increase in strength even beyond 28 days of curing. Additionally, the strength and deformation modulus (E50) of SDS-G increased initially and then decreased during wet-dry cycles, with reductions in mass, volume, and strength significantly were smaller than those observed in SDS-O. Furthermore, the reductions in UCS and E50 induced by freeze-thaw cycles were considerably smaller for SDS-G than for SDS-O, with strength losses of 50.7 % and 88.3 %, respectively, after 13 freeze-thaw cycles. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses revealed that the enhancements observed in SDS-G were attributed to the formation of ettringite (AFt), which effectively fills larger pores between agglomerated soil particles, thereby creating a denser and more stable microstructure in conjunction with hydrated calcium aluminosilicate (C- (A)-S-H) gels.

BackgroundArchaeological limestone artifacts are subject to several deterioration factors that can cause harm while they are buried in soil, such as wet salt soil. Thus, one of the biggest challenges is restoring limestone artifacts that have been discovered from excavations. Understanding the nature of limestone after extraction and the resulting alterations, such as the stone's structural instability and the high salt content of the artifacts, are prerequisites for the restorer. In 1974 AD, King Ramesses III's gate was excavated from the ancient Heliopolis Temple in Cairo. The stones were removed from the soil and left on display outdoors at the same excavation site, where they were subject to seasonal variations in temperature and environmental changes. The main objective of the research is to select the best consolidating materials suitable for the pieces of limestone stone artifacts discovered from archaeological excavations due to their special nature, which affects them as a result of their presence in burial soil for long time. Selecting appropriate consolidating materials with appropriate characteristics was important. In order to withstand a range of environmental circumstances. The characteristics of the ancient stones at the King Ramesses III Gate site were investigated and analyzed to ascertain their true state, and their percentage of damage was calculated by contrasting them with the identical natural limestone that had not been subjected to any harmful influences. After that, experimental samples were used, and the efficacy of the treatment materials was assessed.ResultExperimental study aims to evaluate the effectiveness of some traditional and nano composites materials to improving the properties of stone artifacts extracted from archaeological excavations. Three consolidating solutions were used as follows, paraloid B72 dissolved in acetone 3%, and Calcium hydroxide nanoparticles dissolved in paraloid polymer with acetone at concentrations of 1% and 3%, in addition to nano calcium carbonate dissolved in paraloid polymer with acetone 1% and 3%. The efficiency of the consolidate materials were evaluated using a scanning electron microscope SEM, as well as measuring the water contact angle, in addition to color change testing and measuring the physical and mechanical properties.ConclusionNano materials are considered better than paraloid B72 as a consolidated material and the best outcomes results were obtained with a nano calcium carbonate dissolved in paraloid polymer with acetone 3%.

To enhance the applicability of multiple solid waste road base materials in seasonally frozen soil areas and reduce the negative impact of red mud (RM) on the environment owing to its strong alkalinity, this paper utilizes untreated bayer method RM, fly ash (FA), and phosphogypsum (PG) as raw materials for preparing the road base materials. The mechanical properties, leaching characteristics, and Freeze-thaw (F-T) resistance of the materials from different solid waste systems were investigated through F-T cycle tests, unconfined compressive strength (UCS) tests, and leaching tests. The hydration, sodium solidification, and F-T deterioration mechanisms were revealed using an X-ray diffractometer and a scanning electron microscope. Results indicated that when the mix ratio of RM: FA: PG: cement was 64:28:2:6 (RFP2), the specimen exhibited the best F-T resistance. After 10 F-T cycles, the compressive strength retention rate (BDR) of the specimen was 91.43 %, and the Na+ leaching concentration was 390 mg/L, which still met the Chinese standard. The main hydration products of the material include C-S-H gel and ettringite crystals. These crystals and gels are intertwined and connected to form a dense mesh structure, which improves the material's F-T resistance and sodium solidification effect. The F-T cycle results in the expansion of cracks within the material, which leads to the destruction of the adhesion of the cementitious products, thus causing a deterioration of the strength of the specimen and the reduction of the sodium solidification effect.

Earthen sites, such as the Great Wall of China, are important elements of cultural heritage, but are at high risk of erosion due to environmental changes. In this study, unmanned aerial vehicle low-altitude oblique photography was used to assess the erosion of the Ming Great Wall in Gansu Province. The erosion characteristics (height, depth, area, and ratio) were quantified using a 3D point-cloud model. Combined with onsite sampling and analysis, the deterioration distribution was examined, and the progression of damage summarised using historical images. The degree of erosion in the rammed earth Great Wall was linked to the soluble salt content in the soil. The degree of deterioration of the walls indicates a significantly larger hollowing area on the southern side than on the northern side, and a slightly larger area on the western side than on the eastern side. This paper addresses the challenges of assessing and quantifying erosion development in specific segments and provides a risk assessment of erosion at any point in each segment. It also provides a valuable reference and scientific support for the protection and restoration projects of the Great Wall during the Ming period.

Given the insufficiency in research on the mechanism of fine particle impact on gravelly soil subgrade deterioration, a series of saturated gravelly soil consolidated drained triaxial shear tests was conducted using the GDS triaxial testing system under varying fines contents and effective confining pressures to investigate the effect of fine particle contamination on the static shear characteristics of gravelly soil. The results indicate that: (1) As the fines content increases, the stress-strain curve development pattern transitions from strain softening to strain hardening, with a critical threshold at a fines content of Fc=15%. (2) The addition of fine particles leads to a decrease in the principal stress ratio, brittleness index, peak strength, cohesion, and internal friction angle of the gravelly soil, while the degradation indices increase. The relationship between the degradation indices of peak strength and cohesion and fines content can be described by quadratic functions, and the degradation index of the internal friction angle by a cubic function. (3) With increasing fines content, critical state parameters decrease. The effective stress path shows retracing behavior, becomes shorter, and shifts to the left. (4) The addition of fine particles results in a decrease in the secant modulus, and the volumetric strain-axial strain curve changes from contractive-dilative to purely contractive.