Search Results (284)

Asphalt plant reclaimed powder is a common solid waste in road engineering. Reusing reclaimed powder as filler holds significant importance for environmental protection and resource conservation. The key factors affecting the feasibility of reclaimed powder reuse are its acidity/alkalinity and cleanliness. Traditional evaluation methods, such as the methylene blue test and plasticity index, can assess reclaimed powder properties to guide its recycling. However, these methods suffer from inefficiency, strong empirical dependence, and high variability. To address these limitations, this study proposes a rapid and precise evaluation method for reclaimed powder properties based on Fourier transform infrared spectroscopy (FTIR). To do so, five field-collected reclaimed powder samples and four artificial samples were evaluated. Scanning electron microscopy (SEM), X-ray fluorescence spectroscopy (XRF), and X-ray diffraction (XRD) were employed to characterize their microphase morphology, chemical composition, and crystal structure, respectively. Subsequently, FTIR was used to establish correlations between key acidity/alkalinity, cleanliness, and multiple characteristic peak intensities. Representative infrared characteristic peaks were selected, and a quantitative functional group index (Is) was proposed to simultaneously evaluate acidity/alkalinity and cleanliness. The results indicate that reclaimed powder primarily consists of tiny, crushed stone particles and dust, with significant variations in crystal structure and chemical composition, including calcium carbonate, silicon oxide, iron oxide, and aluminum oxide. Some samples also contained clay, which critically influenced the reclaimed powder properties. Since both filler acidity/alkalinity and cleanliness are affected by clay (silicon/carbon ratio determining acidity/alkalinity and aluminosilicate content affecting cleanliness), this study calculated four functional group indices based on FTIR absorption peaks, namely the Si-O-Si stretching vibration (1000 cm⁻¹) and the CO₃²⁻ asymmetric stretching vibration (1400 cm⁻¹). These indices were correlated with conventional testing results (XRF for acidity/alkalinity, methylene blue value, and pull-off strength for cleanliness). The results show that the Is index exhibited strong correlations (R² = 0.89 with XRF, R² = 0.80 with methylene blue value, and R² = 0.96 with pull-off strength), demonstrating its effectiveness in predicting both acidity/alkalinity and cleanliness. The developed method enhances reclaimed powder detection efficiency and facilitates high-value recycling in road engineering applications. Full article

This study investigates the bond behavior of fabric-reinforced cementitious matrix (FRCM) composites with three common masonry substrates—solid clay bricks (SBs), perforated bricks (PBs), and concrete hollow blocks (HBs)—using knitted polyester grille (KPG) fabric. Through uniaxial tensile tests of the KPG fabric and FRCM system, along with single-lap and double-lap shear tests, the interfacial debonding modes, load-slip responses, and composite utilization ratio were evaluated. Key findings reveal that (i) SB and HB substrates predominantly exhibited fabric slippage (FS) or matrix–fabric (MF) debonding, while PB substrates consistently failed at the matrix–substrate (MS) interface, due to their smooth surface texture. (ii) Prism specimens with mortar joints showed enhanced interfacial friction, leading to higher load fluctuations compared to brick units. PB substrates demonstrated the lowest peak stress (69.64–74.33 MPa), while SB and HB achieved comparable peak stresses (133.91–155.95 MPa). (iii) The FRCM system only achieved a utilization rate of 12–30% in fabric and reinforcement systems. The debonding failure at the matrix–substrate interface is one of the reasons that cannot be ignored, and exploring methods to improve the bonding performance between the matrix–substrate interface is the next research direction. HB bricks have excellent bonding properties, and it is recommended to prioritize their use in retrofit applications, followed by SB bricks. These findings provide insights into optimizing the application of FRCM reinforcement systems in masonry structures. Full article

To enhance agricultural soil health and soil organic carbon (SOC) sequestration, it is important to accurately measure SOC. The aim of this study was to compare common methods for measuring SOC in soils in order to determine the most effective approach among different agricultural land types. The measurement methods of loss-on-ignition (LOI), automated dry combustion (Dumas), and real-time near-infrared spectroscopy (NIRS) were compared. A total of 95 soil core samples, ranging in clay and calcareous content, were collected across a range of agricultural land types from forty-eight fields across five farms in the Southwest of England. There were similar and positive correlations between all three methods for measuring SOC (ranging from r = 0.549 to 0.579; all p < 0.001). On average, permanent grass fields had higher SOC content (6.6%) than arable and temporary ley fields (4.6% and 4.5%, respectively), with the difference of 2% indicating a higher carbon storage potential in permanent grassland fields. Newly predicted conversion equations of linear regression were developed among the three measurement methods according to all the fields and land types. The correlation of the conversation equations among the three methods in permanent grass fields was strong and significant compared to those in both arable and temporary ley fields. The analysed results could help understand soil carbon management and maximise sequestration. Moreover, the approach of using real-time NIRS analysis with a rechargeable portable NIRS soil device can offer a convenient and cost-saving alternative for monitoring preliminary SOC changes timely on or offsite without personnel risks from the high-temperature furnace and chemical reagent adopted in the LOI and Dumas processes, respectively, at the laboratory. Therefore, the study suggests that faster, lower-cost, and safer methods like NIRS for analysing initial SOC measurements are now available to provide similar SOC results as traditional soil analysis methods of the LOI and Dumas. Further studies on assessing SOC levels in different farm locations, land, and soil types across seasons using NIRS will improve benchmarked SOC data for farm stakeholders in making evidence-informed agricultural practices. Full article

Stylolites, common dissolution surfaces in carbonate rocks, form due to localized stress-induced pressure-solution during burial compaction or tectonic contraction. Their morphology and growth are influenced by dissolution kinetics, rock heterogeneity, clay content, burial depth, stress evolution, diagenesis, and pore fluid availability. This study applies the stylolite roughness inversion technique (SRIT), a proven paleopizometer that quantifies the principal vertical stress (σ_v = σ₁) prevailing in strata in the last moments of bedding-parallel stylolites (BPS) formation, to the Late Cretaceous Bagh Group carbonates in the Narmada Basin, India, to estimate their burial paleo-depth. Using the Fourier Power Spectrum (FPS), we obtained 18 σ₁ values from a collection of 30 samples, enabling us to estimate paleo-burial depths for the Bagh Group ranging from 660 to 1320 m. As the Bagh Group burial history is unknown, but as there is no subsequent sedimentary deposition above it, we relate this ca. 1.3 km burial depth to the now eroded thickness of the deposits related to Deccan volcanism at the end of the Cretaceous time, implying a quasi-instantaneous development of the BPS population in the strata. This research highlights the robustness of SRIT for reconstructing burial histories in carbonate sequences and that it can be a reliable way to reconstruct the thickness of eroded deposits in well-constrained geological history. Full article

The cements industry is increasingly under pressure to reduce carbon emissions while maintaining performance standards. Limestone calcined clay cement (LC³) presents a promising low-carbon alternative; however, its performance depends significantly on the type and reactivity of clay used. This study investigates the effect of three common low-grade clay minerals—kaolinite, montmorillonite, and illite—on the behavior of LC³ blends. The clays were thermally activated and characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray fluorescence spectroscopy (XRF), and Blaine air permeability testing to evaluate their mineralogical composition, thermal behavior, chemical content, and fineness. Pozzolanic reactivity was assessed using the modified Chapelle test. Microstructural development was examined through scanning electron microscopy (SEM) of the hydrated specimens at 28 days. The results confirmed a strong correlation between clay reactivity and hydration performance. Kaolinite showed the highest reactivity and fineness, contributing to a dense microstructure with reduced portlandite and enhanced formation of calcium silicate hydrate. Montmorillonite demonstrated comparable strength and favorable hydration characteristics, while illite, though less reactive initially, showed acceptable long-term behavior. Although kaolinite delivered the best overall performance, its limited availability and higher cost suggest that montmorillonite and illite represent viable and cost-effective alternatives, particularly in regions where kaolinite is scarce. This study highlights the suitability of regionally available, low-grade clays for use in LC³ systems, supporting sustainable and economically viable cement production. Full article

In-situ chemical oxidation (ISCO) is a common method to remediate chlorinated ethene contaminants in groundwater. Monitoring the effectiveness of ISCO can be hindered because of insufficient observations to assess oxidant delivery. Advantageously, potassium permanganate, one type of oxidant, provides the opportunity to use its strong electrical signal as a surrogate to track oxidant delivery using time-series borehole geophysical methods, like electromagnetic (EM) induction logging. Here we report a passive ISCO (P-ISCO) experiment, using potassium permanganate cylinders emplaced in boreholes, at a chlorinated ethene contamination site, Naval Air Station Pensacola, Florida. The contaminants are found primarily at the base of a shallow sandy aquifer in contact with an underlying silty-clay confining bed. We used results of the time-series borehole logging collected between 2017 and 2022 in 4 monitoring wells to track oxidant delivery. The EM-induction logs from the monitoring wells showed an increase in EM response primarily along the contact, likely from pooling of the oxidant, during P-ISCO treatment in 2021. Interestingly, concurrent natural gamma-ray (NGR) logging showed a decrease in NGR response at 3 of the 4 wells possibly from the formation of manganese precipitates coating sediments. The coupling of time-series logging and well-chemistry data allowed for an improved assessment of passive ISCO treatment effectiveness. Full article

The deformation control of surrounding rock in the combustion air zone is crucial for the safety and efficiency of underground coal gasification (UCG) projects. Coal-bearing sandstone, a common surrounding rock in UCG chambers, features a brittle structure composed mainly of quartz, feldspar, and clay minerals. Its mechanical behavior under high-temperature and dynamic loading is complex and significantly affects rock stability. To investigate the deformation and failure mechanisms under thermal–dynamic coupling, this study conducted uniaxial impact compression tests using a high-temperature split Hopkinson pressure bar (HT-SHPB) system. The focus was on analyzing mechanical response, energy dissipation, and fragmentation characteristics under varying temperature and strain rate conditions. The results show that the dynamic elastic modulus, compressive strength, fractal dimension of fragments, energy dissipation density, and energy consumption rate all increase initially with temperature and then decrease, with inflection points observed at 400 °C. Conversely, dynamic peak strain first decreases and then increases with rising temperature, also showing a turning point at 400 °C. This indicates a shift in the deformation and failure mode of the material. The findings provide critical insights into the thermo-mechanical behavior of coal-bearing sandstone under extreme conditions and offer a theoretical basis for designing effective deformation control strategies in underground coal gasification projects. Full article

Metabolism, the network of biochemical reactions that powers life, arose under conditions radically different from those on Earth today. Investigating its origins reveals how initially simple chemical processes gradually integrated nucleic acid and then protein catalysts, becoming progressively more complex and regulated until they evolved into the enzyme-rich systems observed in modern organisms. Here, we integrate multiple perspectives on the origin of metabolism, focusing primarily on an evolutionary trajectory from an RNA-based world, where ribozymes, metal ions, coenzymes, small peptides, and other small organic molecules worked in concert, to enzyme-driven metabolic networks. We also address the longstanding debates on whether these early metabolic pathways were largely autotrophic or heterotrophic, and consider so-called “pre-metabolisms” (non-enzymatic networks) as an alternative conceptual framework. We discuss key examples such as the Wood–Ljungdahl (W–L) pathway and the reverse tricarboxylic acid (TCA) cycle, both posited to function under early Earth conditions. Finally, we examine how the environment (e.g., minerals, clays, hydrothermal vents) shaped early metabolism, describe unresolved questions about the Last Common Ancestor’s catalytic repertoire and propose future directions that link geochemical insights with molecular biology and synthetic approaches. Full article

Shallow arable soils (<35 cm depth) are classified as marginal for common agriculture but may still support biomass production from industrial crops like fiber hemp, which has a low indirect land-use change risk. However, little is known about hemp’s performance under such conditions. Therefore, this study investigated the biomass yield and quality of fiber hemp and other crops on a shallow (<35 cm), stony (>15% stone content), and clay-rich (>50% clay content) soil at 800 m above sea level in Southwest Germany (2018–2021). A randomized field trial tested different row widths and nitrogen (N) fertilization levels to assess low-input options for the given type of marginal land. Across years and row widths, hemp achieved average grain dry matter (DM) yields of 1.3 Mg/ha at a fertilization rate of 40 kg N/ha and 1.6 Mg/ha at 120 kg N/ha (with on average 30.9 ± 1.4% crude fat content across treatments). The average stem DM yields accounted for 5.11 Mg/ha (40 kg N/ha) and 6.08 Mg/ha (120 kg N/ha), respectively. Reduced N fertilization (40 kg/ha) lowered DM yields by up to 16% compared to full fertilization (120 kg/ha), but the effect was not significant and weaker at wider row spacing (45 cm). Additionally, maize reached acceptable DM yields (>17 Mg/ha). These findings suggest that shallow soils classified as marginal require reassessment, as they may offer viable opportunities for sustainable industrial hemp cultivation and contribute to a bio-based economy. Full article

The transport and fate of antibiotics are significantly influenced by co-existing colloidal and nanosized substances, such as clay particles. Montmorillonite, a common clay mineral with a thin nano-sheet-like structure, enhances antibiotic (e.g., ciprofloxacin) mobility due to its strong adsorption properties. Nevertheless, little is known about how ciprofloxacin systematically influences the charging and aggregation properties of montmorillonite. This study examines the effect of ciprofloxacin on the electrophoretic mobility and hydrodynamic diameter of Na-montmorillonite under varying pH levels and NaCl concentrations. Results show ciprofloxacin promotes aggregation and alters the surface net charge of Na-montmorillonite at acidic to neutral pH, where ciprofloxacin is positively charged. At higher pH levels, where ciprofloxacin is negatively charged, no significant effects are observed. The observed aggregation behaviors align with predictions based on the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. Specifically, the slow aggregation regime, the fast aggregation regime, and the critical coagulation concentration are identified. The relationship between critical coagulation ionic strength and electrokinetic surface charge density is well explained by the DLVO theory with the Debye–Hückel approximations. Additionally, non-DLVO interactions are inferred. At low NaCl and ciprofloxacin concentrations, minimal changes in aggregation and surface charge suggest dispersed montmorillonite may facilitate ciprofloxacin transport, raising environmental concerns. Full article

Coastal areas are essential for global ‘blue carbon’ burial, significantly impacting the global carbon cycle. To better understand the carbon burial capacity, impact factors, and response mechanisms of surface sediments in different coastline regions, this study investigated the surface sediments of the Spartina alterniflora vegetation, transition, and bare flat areas along Jiangsu coast in China. The results indicated significant changes in organic carbon (OC), inorganic carbon (IC), and various physicochemical property indicators between the three coastal environments. There were also significant differences in the important impact factors of OC and IC in each region. In areas of vegetation, OC and IC influenced each other, while nitrogen (N), clay, and sand were common impact factors. The pH only had a significant impact on OC. In the bare flat area, the important impact factors of OC and IC were identical: OC/IC, clay, salinity (SAL), and sand. However, the important impact factors of OC and IC in the transition area have undergone significant changes. The important impact factors of OC were N, total phosphorus (TP), total sulfur (TS), SAL, and sand. The partial least squares regression analysis results of IC were poor, and there were no important impact factors. This study refined the spatial distribution patterns and response mechanisms to the important impact factors of carbon in different coastal subregions, providing a basis for accurately evaluating the role of coastal wetlands in mitigating global climate change. Full article

This study clarifies the religious traditions underlying the façade-type clay architectural models unearthed from ancient Western Asia by analyzing their iconography apropos each period. The façade-type models considered in this study are one-storied, with a distinct façade, one large opening, and the cella crafted in the niche, three-dimensional, or jar style. The analysis reveals (a) the distribution areas of the most common niche style shifted from the third millennium BC Mesopotamia, through the Middle and Late Bronze Ages and the early Iron Age Levant area, to the Iron Age IIB–C Phoenician areas; (b) the jar style is known only from the second millennium BC Levant and eventually merged with the niche style; and (c) the three-dimensional style is found sporadically. The earlier examples have either a male or a female figure inside the gate, although some have neither. The Levantine examples are without figural representations or with a bird, lions, and female figurines. It may be concluded that two competing religious traditions continued for three millennia, wherein the models with a male figure or without figures represent the tradition of the sovereign god originated in Sumer, whereas those with female figures and decorative motifs reflect the Inana-Ištar cult. Full article

The Nevşehir coals are located in the Central Anatolian Crystalline Complex (CACC), Türkiye, and no reports exist on trace element, nitrogen, and carbon isotope composition data of the Nevşehir coals. The present study aims to geochemically characterise the Nevşehir coals to determine their trace elemental enrichment patterns and possible sources. Nevşehir coals are found within Late Miocene Kızılöz Formation (Arafa Member) rocks. These coals are part of the huminite maceral group; the dominant maceral group is ulminites. The minerals in coals are inorganic, such as oxidised framboidal pyrite, iron oxide minerals, quartz, clay, and carbonate minerals. Coals have great potential regarding trace elements. Benefits might arise from mining and using some of the critical elements derived from coal. Compared with the world coal average, the coal samples in this study are enriched in As (149.25 μg/g), V (245 μg/g), Cr (159 μg/g), Ga (18 μg/g), Ni (216 μg/g), Th (17 μg/g), Zn (143 μg/g), and U (54 μg/g). The arsenic content in this study is associated with inorganic components such as oxidised framboidal pyrite. Vanadium in coal is mainly associated with aluminosilicates and organic matter. Chromium originates from the clay minerals within coals. Uranium in coal is mainly associated with organic matter. Nickel and zinc in coal are predominantly associated with sulphides. The δ¹⁵N contents of the samples are comparable to those of several references, including plants, terrestrial creatures, and organic nitrogen. The δ¹³C–δ¹⁵N isotopic range and average values for four coal samples ranged from −25.66‰ to −25.91‰ (−25.80‰) and 3.6‰ to 4.3‰ (3.9‰), respectively, demonstrating that C3 type modern terrestrial vegetation was common in the palaeomires of the studied coal seams. Full article

The use of basalt fibers, which are employed in various fields, such as construction, automotive, chemical, and petrochemical industries, the sports industry, and energy engineering, is also increasingly common in soil reinforcement studies, another application area of geotechnical engineering, alongside their use in concrete. With this growing application, scientific studies on soil reinforcement with basalt fiber have also gained momentum. This study establishes the effects of basalt fiber on the liquid limit, plastic limit, and strength properties of soils, and the relationships among the liquid limit, plastic limit, and unconfined compressive strength of the soil. For this purpose, 12 mm basalt fiber was used as a reinforcement material in kaolin clay at ratios of 1.0%, 1.5%, 2.0%, 2.5%, and 3.0%. The prepared samples were subjected to liquid limit, plastic limit, and unconfined compressive strength tests. As a result of the experimental studies, the fiber ratio that provided the best improvement in the soil properties was determined, and the relationships among the liquid limit, plastic limit, and unconfined compressive strength were established. The experimental results were then used as input data for an artificial intelligence model. The used neural network (NN) was trained to obtain basalt fiber-to-kaolin ratios based on the liquid limit, plastic limit, and unconfined compressive strength. This model enabled the prediction of the fiber ratio that provides the maximum improvement in the liquid limit, plastic limit, and compressive strength without the need for experiments. The NN results were in great agreement with the experimental results, demonstrating that the fiber ratio providing the maximum improvement in the soil properties can be identified using the NN model without requiring experimental studies. Moreover, the performance and reliability of the NN model were evaluated using 5-fold cross-validation and compared with other AI methods. The ANN model demonstrated superior predictive accuracy, achieving the highest correlation coefficient (R = 0.82), outperforming the other models in terms of both accuracy and reliability. Full article

With the development of the offshore wind industry in China, the amount of offshore wind turbines has increased rapidly. Large-diameter steel monopile foundations of offshore wind turbines have been widely adopted in China with lots of marine clay located. However, the conventional offshore wind monopile bearing capacity prediction from the American Petroleum Institute (API) based on the small-diameter flexible pile field test is inaccurate with the rigid mechanism of large-diameter monopile causing economically loss. The piezocone penetration test (CPTU) is a common marine in situ test to exactly acquire soil parameters. Therefore, a CPTU-based offshore wind monopile rigid mechanism inference method is proposed. A creative numerical offshore wind power monopile and CPTU combined model is established through COMSOL. A self-compiling parameter function is applied to soil modeling and an innovative mobile boundary function is created to simulate CPTU penetration. Through the model, real-time CPTU data can be acquired when monopile is applied with different horizontal loads. The peripile soil stress change can be timely detected by CPTU. Through CPTU data, the monopile rigid bearing mechanism is verified. A rigid rotation center is found at the 60% point of the inserted monopile. The method is an important foundation for the next step of monopile bearing capacity research. Full article