Search Results (759)

The eruption of the Cumbre Vieja volcano on 19 September 2021 resulted in the deposition of over 20 million cubic meters of tephra, posing significant environmental and logistical challenges in the affected areas. This study aimed to explore the valorization of volcanic ash (VA) by evaluating its potential use in producing sustainable mortar by incorporating it as a replacement for cement or sand. Various experimental mixtures were prepared with different proportions of VA which substituted either cement or sand, and these mixes were characterized through a mechanical and microstructural campaign. Additionally, shrinkage was evaluated for the mixtures which showed good mechanical results. The results suggest that partially replacing cement with up to 15% ground VA as well as substituting sand with up to 25% VA are promising strategies for the production of sustainable mortar mixes. This research contributes to the understanding of the influence of VA in cementitious matrices and offers a novel approach for integrating locally available geomaterials into infrastructure design in volcanic active regions. Full article

Every year, a billion tires are discarded worldwide, with only a small percentage being recycled. This leads to significant environmental hazards, such as fire risks and improper disposal. Silty sand also presents technical challenges due to its poor shear strength, susceptibility to erosion, and low permeability. This study explores the incorporation of crumb rubber derived from waste tires into silty sand to enhance its mechanical properties. Crumb rubber particles of varying sizes (3–6 mm, 5–10 mm, and 10–20 mm) were mixed with silty sand at 0%, 3%, 6%, and 9% percentages, respectively. Triaxial compression tests of unconsolidated and consolidated undrained tests with cell pressures of 100, 300, and 500 kPa were conducted. The deviatoric stress, shear stress, and stiffness modulus were investigated. The results revealed that the addition of crumb rubber significantly increased the deviatoric and shear stresses, especially at particle sizes of 5–10 mm, with contents of 3%, 6%, and 9%. Additionally, the stiffness modulus was notably reduced in the mixture containing 6% crumb rubber tire. These findings suggest that incorporating crumb rubber tires into silty sand not only improves silty sand performance but also offers an environmentally sustainable approach to tire waste recycling, making it a viable strategy for silty sand stabilization in construction and geotechnical engineering performance. Full article

The Kekeya oilfield is located at the southwestern edge of the Tarim Basin, in the southern margin of the Yecheng depression, at the western end of the second structural belt of the northern foothills of the Kunlun Mountains. It is one of the important oil and gas fields in western China, with significant oil and gas resource potential in the X4-X5 section of the Xihepu Formation. This study focuses on the edge of the alluvial fan depositional system, employing various techniques, including core data and well logging data, to precisely characterize the sand body architecture and comprehensively analyze the reservoir architecture in the study area. First, the regional geological background of the area is analyzed, clarifying the sedimentary environment and evolutionary process of the Xihepu Formation. Based on the sedimentary environment and microfacies classification, the sedimentary features of the region are revealed. On this basis, using reservoir architecture element analysis, the interfaces of the reservoir architecture are finely subdivided. The spatial distribution characteristics of the planar architecture are discussed, and the spatial distribution and internal architecture of individual sand body units are analyzed. The study focuses on the spatial combination of microfacies units along the profile and their internal distribution patterns. Additionally, a quantitative analysis of the sizes of various types of sand bodies is conducted, constructing the sedimentary model for the region and revealing the control mechanisms of different sedimentary architectures on reservoir properties and oil and gas accumulation patterns. This study pioneers a quantitative model for alluvial fan fringe in gentle-slope basins, featuring the following: (1) lobe width-thickness ratios (avg. 128), (2) four base-level-sensitive boundary markers, and (3) a retrogradational stacking mechanism. The findings directly inform reservoir development in analogous arid-climate systems. This research not only provides a scientific basis for the exploration and development of the Kekeya oilfield but also serves as an important reference for reservoir architecture studies in similar geological contexts. Full article

The eastern North Pacific Ocean coastline (from the Salish Sea to the western Aleutian Islands) is highly glaciated with relic sediment deposits scattered throughout a highly contoured and variable bathymetry. Oceanographic conditions feature strong currents and tidal exchange. Sand wave fields are prominent features within these glaciated shorelines and provide critical habitat to sand lance (Ammodytes spp.). Despite an awareness of the importance of these benthic habitats, attributes related to their structure and characteristics remain undocumented. We explored the micro-bathymetric morphology of a subtidal sand wave field known to be a consistent habitat for sand lance. We calculated geomorphic attributes of the bedform habitat, analyzed sediment composition, and measured oceanographic properties of the associated water column. This feature has a streamlined teardrop form, tapered in the direction of the predominant tidal current. Consistent flow paths along the long axis contribute to well-defined and maintained bedform morphology and margin. Distinct patterns in amplitude and period of sand waves were documented. Strong tidal exchange has resulted in well-sorted medium-to-coarse-grained sediments with coarser sediments, including gravel and cobble, within wave troughs. Extensive mixing related to tidal currents results in a highly oxygenated water column, even to depths of 80 m. Our analysis provides unique insights into the physical characteristics that define high-quality habitat for these fish. Further work is needed to identify, enumerate, and map the presence and relative quality of these benthic habitats and to characterize the oceanographic properties that maintain these benthic habitats over time. Full article

Beach Sand Mycobiome is currently among the most important health challenges for viticulture in the world. Remarkably, the study of fungal communities in coastal beach sand and recreational waters remains underexplored despite their potential implications for human health. This research aimed to assess the prevalence of fungal species and the antifungal susceptibility profiles of fungi recovered from the beaches of the Persian Gulf and the Sea of Oman. Sand and seawater samples from 39 stations distributed within 13 beaches along the coastline were collected between May and July 2023. The grown isolates were identified at the species level based on morphological characteristics and DNA sequencing. Antifungal susceptibility testing was performed according to the Clinical Laboratory Standards Institute guidelines. Of 222 recovered isolates, 206 (92.8%) filamentous fungi and 16 (7.2%) yeast strains were identified. Sand-recovered fungi comprised 82.9%, while water-originated fungi accounted for 17.1%. The DNA sequencing technique categorized 191 isolates into 13 genera and 26 species. The most recovered genus was Aspergillus (68.9%), and Aspergillus terreus sensu stricto was the commonly identified species (26.14%). Voriconazole was the most effective antifungal drug against Aspergillus species. Research on fungal contamination levels at these locations could provide a foundation for establishing regulatory frameworks to diminish fungal risks, thereby enhancing public health protection. The ecological significance of fungal communities in sandy beaches to human infections remains to be explored, and earlier reports in the literature may motivate researchers to focus on detecting this mycobiome in natural environments where further investigation is warranted. Ultimately, our discovery serves as a reminder that much remains to be learned about pathogenic fungi and underscores the need for vigilance in areas where emerging pathogens have not yet been identified. Full article

The sedimentary characteristics and model of the shallow-water delta front are of great significance for the development of oil and gas reservoirs. At present, there are great differences in the understanding of the distribution patterns of estuary dams in the shallow-water delta front. Therefore, this paper reveals the distribution characteristics of estuary dams through the detailed dissection of the Qing 1 Member in the Daqingzijing area and establishes a completely new distribution pattern of estuary dams. By using geological data such as logging and core measurements, sedimentary microfacies at the shallow-water delta front are classified and logging facies identification charts for each sedimentary microfacies are developed. Based on the analysis of single-well and profile facies, the sedimentary evolution laws of the Qing 1 Member reservoirs are analyzed. On this basis, the sedimentary characteristics and model of the lacustrine shallow-water delta front are established. The results indicate that the Qing 1 Member in the Daqingzijing area exhibits a transitional sequence from a delta front to pro-delta facies and finally to deep lacustrine facies, with sediments continuously retrograding upward. Subaqueous distributary channels and estuary dams constitute the skeletal sand bodies of the retrogradational shallow-water delta. The estuary dam sand bodies are distributed on both sides of the subaqueous distributary channels, with sand body development gradually decreasing in scale from bottom to top. These bodies are intermittently distributed, overlapping, and laterally connected in plan view, challenging the conventional understanding that estuary dams only occur at the bifurcation points of underwater distributary channels. Establishing the sedimentary characteristics and model of the shallow-water delta front is of great significance for the exploration and development of reservoirs with similar sedimentary settings. Full article

Glass microspheres are essential components in horizontal road markings due to their retroreflective properties, enhancing visibility and safety under low-light conditions. Traditionally produced from soda-lime glass made with high-purity silica from sand, their manufacturing raises environmental concerns amid growing global sand scarcity. This study explores the viability of rice husk ash (RHA)—a high-silica byproduct of rice processing—as a sustainable raw material for microsphere fabrication. A glass composition containing 70 wt% SiO₂ was formulated using RHA and melted at 1500 °C. Microspheres were produced through flame spheroidization and characterized following the Brazilian standard NBR 16184:2021 for Type IB beads. The RHA-derived microspheres exhibited high sphericity, appropriate size distribution (63–300 μm), density of 2.42 g/cm³, and the required acid resistance. UV-Vis analysis confirmed their optical transparency, and the refractive index was measured as 1.55 ± 0.03. Retroreflectivity tests under standardized conditions revealed performance comparable to commercial counterparts. These results demonstrate the technical feasibility of replacing conventional silica with RHA in glass microsphere production, aligning with circular economy principles and promoting sustainable infrastructure. Given Brazil’s significant rice production and corresponding RHA availability, this approach offers both environmental and socio-economic benefits for road safety and material innovation. Full article

Traditional playground settings are often less effective in fostering STEAM (Science, Technology, Engineering, Arts, and Mathematics)-related activities, as fixed play structures tend to restrict the diversity of play behaviors and inhibit children’s ability to engage in self-directed, imaginative exploration. Using a research-through-design methodology, this study investigated how playground design (temporary landscape interventions) influences children’s engagement in informal STEAM learning activities and enhances the STEAM learning affordances of the playground. Conducted at an early learning center in Lubbock, Texas, the research involved GIS-based Environment–Behavior Mapping (E-B Mapping) and video analysis of 21 preschool-age children to compare pre- and post-intervention STEAM learning behaviors. The intervention incorporated fourteen nature-based landscape elements—such as sand and water play areas, sensory gardens, loose parts, art areas, etc.—to enhance affordances for informal STEAM activities. The results showed a marked decrease in passive behaviors and a notable rise in constructive play; collaborative interactions; and STEAM-related activities such as building, hypothesizing, observing, and experimenting. Engagement shifted away from fixed play structures to more diverse and naturalized play settings. The findings underscore the critical role of integrating diverse landscape settings and elements into playgrounds in enriching STEAM learning experiences for young children. Full article

The durability and fire resilience of concrete structures are increasingly critical in modern construction, particularly under elevated-temperature exposure. With this context, the current study explores the thermal and microstructural characteristics of geopolymer-based ultra-high-performance concrete (G-UHPC) incorporating quartz powder (QP) and silica fume (SF) after exposure to elevated temperatures. SF was used at 15% and 30% to partially replace the precursor material, while QP was used at 25%, 30%, and 35% as a partial replacement for fine sand. The prepared specimens were exposed to 200 °C, 400 °C, and 800 °C, followed by air cooling. Mechanical strength tests were conducted to evaluate compressive and flexural strengths, as well as failure patterns. Microstructural changes due to thermal exposure were assessed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Among the prepared mixtures, the 30SF35QP mixture exhibited the highest compressive strength (156.0 MPa), followed by the 15SF35QP mix (146.83 MPa). The experimental results demonstrated that G-UHPC underwent varying levels of thermal degradation across the 200–800 °C range yet displayed excellent resistance to thermal spalling. At 200 °C, compressive strength increased due to enhanced geopolymerization, with the control mix showing a 29.8% increase. However, significant strength reductions were observed at 800 °C, where the control mix retained only 30.8% (32.0 MPa) and the 30SF25QP mixture retained 28% (38.0 MPa) of their original strengths. Despite increased porosity and cracking at 800 °C, the 30SF35QP mixture exhibited superior strength retention due to its denser matrix and reduced voids. The EDS results confirmed improved gel stability in the 30% SF mixtures, as evidenced by higher silicon content. These findings suggest that optimizing SF and QP content significantly enhances the fire resistance and structural integrity of G-UHPC, providing practical insights for the design of sustainable, high-performance concrete structures in fire-prone environments. Full article

This study establishes a multiphysics coupling model of acoustics, mechanics, and electrostatics through COMSOL, systematically explores the sound field distribution and stress–strain characteristics of tailing particles in sand silos under different frequencies of ultrasonic radiation, and proposes an optimization scheme for the sound field. The simulation results show that under 28 kHz ultrasonic radiation, the amplitude of sound pressure in the sand silo (173 Pa) is much lower than that at 40 kHz (1220 Pa), which can avoid damaging the original settlement mode of the tail mortar. At the same time, the periodic fluctuation amplitude of its longitudinal sound pressure is significantly greater than 25 kHz, which can promote settlement by enhancing particle tensile and compressive stress, achieving the best comprehensive effect. The staggered placement scheme of the transducer eliminates upward disturbance in the flow field by changing the longitudinal opposing sound field to oblique propagation, reduces energy dissipation, and increases the highest sound pressure level in the compartment to 130 dB. The sound pressure distribution density is significantly improved, further enhancing the settling effect. This study clarifies the correlation mechanism between ultrasound parameters and tailings’ settling efficiency, providing a theoretical basis for parameter optimization of ultrasound-assisted tailing treatment technology. Its results have important application value in the optimization of tailings settling in metal mine tailing filling. Full article

Additive manufacturing (AM) has brought significant breakthroughs to the construction sector, such as the ability to fabricate complex geometries, enhance efficiency, and reduce both material usage and construction waste. However, several challenges must still be addressed to fully transition from conventional construction practices to innovative and sustainable green alternatives. This study investigates the use of non-cementitious traditional mixtures for green construction applications through 3D printing using Liquid Deposition Modeling (LDM) technology. To explore the development of mixtures with enhanced physical and mechanical properties, natural pine and cypress wood shavings were added in varying proportions (1%, 3%, and 5%) as sustainable additives. The aim of this study is twofold: first, to demonstrate the printability of these eco-friendly mortars that can be used for conservation purposes and overcome the challenges of incorporating bio-products in 3D printing; and second, to develop sustainable composites that align with the objectives of the European Green Deal, offering low-emission construction solutions. The proposed mortars use hydrated lime and natural pozzolan as binders, river sand as an aggregate, and a polycarboxylate superplasticizer. While most studies with bio-products focus on traditional methods, this research provides proof of concept for their use in 3D printing. The study results indicate that, at low percentages, both additives had minimal effect on the physical and mechanical properties of the tested mortars, whereas higher percentages led to progressively more significant deterioration. Additionally, compared to molded specimens, the 3D-printed mortars exhibited slightly reduced mechanical strength and increased porosity, attributable to insufficient compaction during the printing process. Full article

Biopolymers, owing to their environmentally friendly and sustainable characteristics, have become a promising alternative for soil stabilization in geotechnical engineering. The application of protein-based biopolymers as binders for soil stabilization is less prevalent in geotechnical engineering compared to polysaccharide-based biopolymers. This study explores the potential of gelatin, a protein-based biopolymer derived from animal collagen, for stabilizing silty sand and improving its geotechnical properties. Gelatin was mixed into the soil at concentrations ranging from 0.25% to 2% of the dry weight of soil, and its effects on various soil characteristics were evaluated. The tests conducted include liquid limit, plastic limit, compaction behavior, and unconfined compressive strength (UCS); the addition of 1% gelatin led to an approximate 1.69 times increase in the strength of the unamended soil. After 28 days of curing, the UCS improved by approximately 5.03 times compared to the untreated soil, and the treated soil exhibited increased resistance to deformation under load. Microstructural analysis using scanning electron microscopy (SEM) revealed that gelatin facilitated the formation of a cohesive matrix, enhancing particle bonding and reducing void spaces within the soil. Carbon footprint analysis (CFA) conducted on an isolated footing stabilized with gelatin showed that the carbon emissions were reduced by 99.8% and 99% compared to traditional stabilizers such as lime and cement. Additionally, the interaction between the biopolymer and the fine-grained soil is distinctly evident in the FTIR and XRD analysis through hydrogen bonding and the formation of cementitious compounds. Full article

This study investigates the development of a fully rubberized fine-aggregate engineered geopolymer composite (R-EGC) by replacing quartz sand with waste rubber particles (RPs). The influence of the rubber aggregate-to-binder mass ratio (A/B) on the performance of the R-EGC was systematically examined from both macroscopic and microscopic perspectives. Quantitative analysis of crack width and number was conducted using binarized image-processing techniques to elucidate the crack propagation patterns. Moreover, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were employed to analyze the interfacial transition zone (ITZ) between the rubber aggregates and the geopolymer matrix under varying A/B ratios, aiming to explore the underlying failure mechanisms of the R-EGC. The research results indicated that the flowability of the R-EGC decreased gradually with increasing A/B ratio. The flowability of R-0.1 was 73.5%, outperforming R-0.2 and R-0.3 (66% and 65%, respectively). R-0.1 achieved the highest compressive strength of 35.3 MPa (compared to 31.2 MPa and 28.4 MPa for R-0.2 and R-0.3, respectively). R-0.3 demonstrated the most effective crack-control capability, with a tensile strength of 3.96 MPa (representing increases of 11.9% and 3.7% compared to R-0.1 and R-0.2, respectively) and the smallest crack width of 104 μm (indicating reductions of 20.6% and 43.5% compared to R-0.1 and R-0.2, respectively). R-0.2 exhibited the best ductility, with an ultimate tensile strain of 8.33%. Microstructural tests revealed that the interfacial transition zone (ITZ) widths for R-0.1, R-0.2, and R-0.3 were 2.47 μm, 4.53 μm, and 1.09 μm, respectively. An appropriate increase in the ITZ width was found to be beneficial for enhancing tensile ductility, but it compromised the crack-control ability of the R-EGC, thereby reducing its durability. Overall, this study clarifies the fundamental influence of the A/B ratio on the mechanical performance of the R-EGC. The findings provide valuable insights for future research in this field. Full article

Substrate is an important component of a fish’s habitat environment. Fish preferences for substrate influence their growth and development, feeding, hiding, schooling, and reproduction. To explore the habitat preference of Brachymystax tsinlingensis, this study was conducted on the preferences of B. pre-smolts, post-smolts, and juveniles for three substrate colors, white, blue, and black, and four substrate types, sand (<0.5 cm in diameter), small gravel (1–2 cm in diameter), medium gravel (5–7 cm in diameter), and large gravel (12–16 cm in diameter), which were investigated in light (10–60 lx) and dark (no light) environments. The results showed that the individual populations of B. tsinlingensis in three periods of time had a clear preference for substrate color, preferring black substrate and staying away from blue substrate under both light and dark environmental conditions; B. tsinlingensis pre-smolts and post-smolts preferred sandy substrate, and juveniles preferred medium gravel substrate. The choice of substrate color and substrate type by B. tsinlingensis is a manifestation of the living environment characteristics of this species, which is conducive to their hiding, better avoidance of enemies, and improvement of their survival rate. Based on the research results and the early biological characteristics of B. tsinlingensis, it is recommended to use black or dark substrate during the cultivation of B. tsinlingensis fry. During the larval fish stage, a sandy substrate environment should be provided. During the juvenile fish stage, a medium-gravel environment should be provided. Full article

The sustainable development of geotechnical infrastructure necessitates using durable, efficient, and environmentally resilient reinforcement materials. This study investigates the pullout performance of geostraps to assess their potential as a sustainable alternative to conventional geosynthetics. This study focuses on the pullout performance of geostraps, flexible, polymeric reinforcement materials. There has not been a thorough study of their pullout resistance, which directly affects the stability and durability of reinforced soil structures. Pullout tests were conducted on sandy soil in a controlled environment. The experimental findings from the pullout test were then validated in a numerical model. The model was used to determine the pullout resistance of different grades of geostraps for comparative analysis. This helped to identify the possible application areas based on the pullout capacity of various grades. The results obtained for the geostraps were then compared with those in the established literature on geogrids. Initially, the pullout resistance of the M65 geostrap was up to 20% higher than that of a biaxial geogrid. This makes it a suitable option for reinforced earth applications. However, the maximum pullout resistance of geogrids was up to 8% higher than that of geostraps when subjected to a surcharge of 17 kN m⁻² in poorly graded sand. This study highlights the potential of geostraps as reinforcement materials, particularly in challenging environments where conventional geosynthetics may underperform. Future research may explore their behaviour with different soil types and other controlled environmental factors to establish their broader applicability and design charts. Full article