Sand Samples Research Articles

Rapid, graded sand preparation method using grain size distribution results for cement mortar testing

Adhering to ASTM C109/C109M-20 standards ensures quality in cement mortar specimens. However, achieving the required sand gradation per ASTM C778-21 can be challenging. This paper presents a faster method for adjusting sand gradation without compromising ASTM quality standards. The proposed method involves analyzing six silica sand samples of different gradations, pre-screening sands, using Excel Solver for optimal mixture ratios, making automated gradation tweaks with precise calculations, and validating the gradation to ensure ASTM compliance. After making the adjustments, compressive strength tests were conducted on mortars with the modified sands, and the results were compared with those of standard-graded sand. Based on statistical analysis, the new method yielded reliable outcomes with compressive strengths similar to standard sands. This innovation offers a more efficient alternative, paving the way for streamlined practices in civil engineering.

The comparative plastisphere microbial community profile at Kung Wiman beach unveils potential plastic-specific degrading microorganisms.

Plastic waste is a global environmental issue that impacts the well-being of humans, animals, plants, and microorganisms. Microplastic contamination has been previously reported at Kung Wiman Beach, located in Chanthaburi province along with the Eastern Gulf of Thailand. Our research aimed to study the microbial population of the sand and plastisphere and isolate microorganisms with potential plastic degradation activity. Plastic and sand samples were collected from Kung Wiman Beach for microbial isolation on agar plates. The plastic samples were identified by Fourier-transform infrared spectroscopy. Plastic degradation properties were evaluated by observing the halo zone on mineral salts medium (MSM) supplemented with emulsified plastics, including polystyrene (PS), polylactic acid (PLA), polyvinyl chloride (PVC), and bis (2-hydroxyethyl) terephthalate (BHET). Bacteria and fungi were identified by analyzing nucleotide sequence analysis of the 16S rRNA and internal transcribed spacer (ITS) regions, respectively. 16S and ITS microbiomes analysis was conducted on the total DNA extracted from each sample to assess the microbial communities. Of 16 plastic samples, five were identified as polypropylene (PP), four as polystyrene (PS), four as polyethylene terephthalate (PET), two as high-density polyethylene (HDPE), and one sample remained unidentified. Only 27 bacterial and 38 fungal isolates were found to have the ability to degrade PLA or BHET on MSM agar. However, none showed degradation capabilities for PS or PVC on MSM agar. Notably, Planococcus sp. PP5 showed the highest hydrolysis capacity of 1.64 ± 0.12. The 16S rRNA analysis revealed 13 bacterial genera, with seven showing plastic degradation abilities: Salipiger, Planococcus, Psychrobacter, Shewanella, Jonesia, Bacillus, and Kocuria. This study reports, for the first time of the BHET-degrading properties of the genera Planococcus and Jonesia. Additionally, The ITS analysis identified nine fungal genera, five of which demonstrated plastic degradation abilities: Aspergillus, Penicillium, Peacilomyces, Absidia, and Cochliobolus. Microbial community composition analysis and linear discriminant analysis effect size revealed certain dominant microbial groups in the plastic and sand samples that were absent under culture-dependent conditions. Furthermore, 16S and ITS amplicon microbiome analysis revealed microbial groups were significantly different in the plastic and sand samples collected. We reported on the microbial communities found on the plastisphere at Kung Wiman Beach and isolated and identified microbes with the capacity to degrade PLA and BHET.

Pore Water Conversion Characteristics during Methane Hydrate Formation: Insights from Low-Field Nuclear Magnetic Resonance (NMR) Measurements

Understanding the conversion characteristics of pore water is crucial for investigating the mechanism of hydrate accumulation; however, research in this area remains limited. This study conducted methane hydrate formation experiments in unconsolidated sands using an in-house low-field nuclear magnetic resonance (NMR) system. It focused on pore water conversion characteristics and influencing factors such as initial water saturation and sand particle sizes. Results show that methane hydrate formation enhances the homogeneity of the effective pore structure within sand samples. The conversion rate of pore water is significantly influenced by differences in heat and mass transfer capacity, decreasing as initial water saturation and sand size increase. Pore water cannot be fully converted into hydrates in unconsolidated sands. The final conversion ratio of pore water in water-poor sand samples nears 97%, while in water-rich sand samples, it is only 65.80%. Sand particle size variation has a negligible impact on the final conversion ratio of pore water, with ratios exceeding 94% across different particle sizes, differing by less than 3%.

Dynamic behavior and characteristics of geogrid-reinforced sand under cyclic loading

This paper evaluated the benefits of geogrid-reinforced sand samples and investigated the effect of different factors contributing to the dynamic behavior, which included the geogrid type, arrangement of reinforcement, confining pressure and dynamic stress amplitude. Four geogrids of different aperture geometries (two biaxial geogrids and two triaxial geogrids) produced by 3D printing technology were used. The research was experimentally carried out by conducting dynamic triaxial tests to investigate the axial cumulative strain, dynamic elastic modulus and damping ratio of the samples. The test results demonstrated the potential benefit of installing geogrids in subgrade soils. Less axial cumulative strain, damping ratio and larger dynamic elastic modulus were measured under cyclic loading for geogrid-reinforced samples compared to those unreinforced samples. The geogrid type and reinforcement arrangement had noticeable impacts on the samples’ dynamic performance. Of the four model geogrids tested, the triaxial geogrid with triangle aperture performed consistently better than the other three. Under large confining pressures and dynamic stress amplitudes, there was no appreciable improvement in the dynamic performance of the samples reinforced with the two triaxial geogrids. The results also showed that the double reinforcement arrangement consistently yielded better improvement. This study explored preliminarily the feasibility of applying 3D printing technology in geotechnical model tests, which shed light on the understanding of dynamic response of geogrid-reinforced soil and the optimization of geogrids.

Analysis of Soil Permeability Batu Bulan Dam’s Right Secondary Irrigation Canal in Sumbawa, Indonesia

The assessment of soil and water conditions is crucial in planning and management of an irrigation system. This study focused primarily on investigating the fine aggregate flow absorption conditions of the soil from the secondary irrigation canal of the Batu Bulan Dam’s right bank in Sumbawa Regency, Indonesia. Soil permeability level was determined in a laboratory setting using standard water absorption parameters of an irrigation canal. Analysis of specific gravity and absorption of fine aggregate showed that sand sample (A) had a bulk specific gravity of 2.53, a saturated surface dried specific gravity of 2.55, and a water absorption of 0.92 percent. Sand sample (B) had a specific gravity of 2.53, a saturated surface dried specific gravity of 2.56 and an absorption rate of 1.02%. According to the characteristics of fine aggregate (sand) standard, the specific gravity range is between 1.6 and 3.3. Thus, the mud content value of the sand samples follows the standards set by SNI. The sand sample (A) exhibited a water absorption rate of 0.92%, whereas sand sample (B) displayed a water absorption rate of 1.02%. As per the Fine Aggregate Inspection Standard, the upper limit for water absorption in fine aggregate is prescribed as 3% of dry weight for concrete with abrasion and 5% of dry weight for non-abrasive concrete. Thus, the mud content value of the sand samples complies with SNI standards. The results suggest that future irrigation strategies should consider the distinct characteristics of native aquifers, the routes of groundwater movement, and the conveyance of soil nutrients to ensure the sustainability of agricultural development in secondary irrigation areas adjacent to reservoirs.

Mechanical transport revealed by optical textures of heavy minerals in aeolian sand: A case study in the Badain Jaran Desert, Northwestern China

Determining whether and to what extent the relative abundance of heavy minerals in original detrital assemblage has been modified by mechanical transport is beneficial for understanding regional historical climate changes and acquiring modern sediment provenance information. Utilizing the frequency of surface mechanical optical textures of heavy minerals may be an effective approach to address this question. However, the connection between the frequency surface mechanical optical textures of heavy minerals and the variations in the relative abundance of these minerals remains uncertain. In this study, 12 modern aeolian sand samples were collected from the Badain Jaran Desert in hyper arid region of northwestern China, characterized by weak weathering to analyze their relative contents of five major heavy minerals. Then, 3796 transparent heavy mineral grains were photographed under the parallel light of a polarizing microscope, and the frequency of 13 surface mechanical optical textures were calculated. The results reveal that the variations in the relative abundance of heavy minerals are substantially influenced by mechanical transport. The decrease in the relative abundance of heavy minerals with weak mechanical stability primarily attributed to mechanical collision. Conversely, the variations in the relative abundance of heavy minerals with strong mechanical stability are primarily influenced by mechanical abrasion. Therefore, mechanical transport impact on the relative abundance of heavy minerals in regions with weak chemical weathering. Establishing heavy mineral characteristic indices for provenance studies using the relative abundance of mechanically unstable minerals may not directly indicate transport distance but rather the strength of wind forces, which have significant potential in palaeo wind regime studies. This study expands the research field of sediment surface micromorphology and has potential applications in inferring past climate changes and determining modern sediment provenance.

Source of arsenic pollution in southern Indus alluvial plain aquifers, Pakistan

Aquifers in Indus alluvial plain are naturally polluted by arsenic (As). Millions of population in Pakistan use groundwater for drinking is exposed to As ingested diseases. Present investigations were focused on the mobilization mechanism of As in the alluvial aquifers, in Matiari district of Pakistan, which is mainly covered by alluvial sediments of Holocene and Pleistocene age. These sediments are weathered from Himalayas and its neighboring regions and are primarily deposited by Indus River. About 94 samples of groundwater were collected from various localities of Matiari district. Physico-chemical data revealed that 60% of wells exceed 10 μg/L, WHO permissible standard for drinking water. Low nitrate and neutral to near neutral pH and negative Eh in most of the wells are indicative of reducing conditions in the aquifers. Ancient courses of Indus river and domestic and agricultural wastes could be an important source of organic matter. Microbiodegradation of organic matter has created reducing conditions in the aquifer, which trigger the reduction of sedimentary iron oxyhydroxides and the mobilize As in shallow aquifers of Matiari. A borehole was also drilled to decipher the lithological and geochemical characteristics of aquifer material. Elemental, petrographic and SEM-EDS data revealed that sediments are comprised of brown aquitard clay and well sorted grey fine sand. Arsenic in sand and clay samples ranged between 0.8 and 3.9 mg/kg and 0.3–3.2 mg/kg respectively. Dominant minerals in the aquifers sediments are phlogopite and biotite. Leaching of these minerals under reducing conditions is likely to provide higher concentration of As in the groundwater of the area.

The Effect of Operating Variables on the Performance of Column Flotation of Silica Sand

This paper presents the results of a study performed on silica sand samples to determine the effect of operating parameters (collector type and dosage, solids content in the pulp, pulp pH and air flow rate) on the concentrate grade and mass recovery in laboratory-scale column flotation. Through the analysis of variance (ANOVA), it was determined that the pulp pH had a significant impact on all four of the observed grade parameters (mass contents of SiO2, Al2O3, Fe2O3 and TiO2 in the concentrate). Air flow rate had a significant impact on the mass contents of SiO2 and Al2O3. The solids content in the pulp only significantly affected the mass content of Fe2O3. The mass recovery was significantly influenced by the pulp pH, with a high level of significance (p-value (p) = 0.002917), as well as by the air flow rate (p = 0.010285). On the basis of a model of the relationship between the respective grade parameters and tested operating variables, it was determined that with the use of the Aeromine 3030C collector (at a dosage of 500 g/t) the highest-grade concentrate regarding the mass contents of SiO2, Al2O3 and TiO2 was achieved with a pulp pH within a range from 2.4 to 3 and an air flow rate above 26 L/h. The lowest mass content of Fe2O3 in the concentrate was achieved at a pulp pH in a range from 2.2 to 2.8 and a solids content in the pulp between 2.0% and 3.5%.

Physico-chemical alteration of pyroxene in coastal environments: Empirical constraints from New Zealand and the Azores

Developing approaches to determine the modes of transport and weathering of mafic detrital minerals in natural sedimentary environments is critical to our understanding of sediment production, dispersal and provenance, as well as carbon capture under natural and enhanced weathering regimes. We integrated the characterisation of morphological and surface textures with the surface composition of recent detrital clinopyroxene grains concentrated in a sandy coastal area from the western North Island of New Zealand and a rocky shore area of Santa Maria Island in the Azores Archipelago. Using the compactness shape descriptor, 341 grains were subdivided into elongated, elongated angular, euhedral, angular and subangular groups, with each group further characterised using morphological and microtextural indicators of abrasion, breakage and dissolution/chemical weathering. In both studied environments, the clinopyroxenes are dominated by elongated to angular shapes with flat cleavage surfaces and conchoidal fractures. This is consistent with dominant subaqueous transport by rivers and longshore currents for New Zealand, and dominant wave action with limited sediment supply by rivers along the rocky shore of Santa Maria. More abundant subabraded and abraded shapes with bulbous and elongated depression microtextures are observed in New Zealand, which indicates additional effects by aeolian transport that are not seen in Santa Maria. Consistent with semi-quantitative EDS spot analyses that document fresh clinopyroxenes surfaces, chemical weathering textures are very rare to absent. In Santa Maria, sampling of recent beach sand was complemented by ∼125 kyr-old palaeobeach clinopyroxenes, but these yielded similar textural results without evidence for chemical weathering. However, the surface of these older clinopyroxenes includes small adhering smectite (typically <50 μm in width and a few μm in thickness) interpreted to reflect incipient cementation with buffering of acidic fluids by more reactive lithic fragments in the deposits. The lack of chemical weathering but pervasive evidence for mechanical breakage of clinopyroxenes indicate that, at the sand size, these minerals break faster than they dissolve due to frequent subaqueous and/or aeolian reworking in the studied high-energy environments and temperate climatic conditions.

The Liquefaction Behavior of Leachate-Contaminated of Sand under Cyclic Loads

Uncontrolled solid waste affects the stress-strain behavior of the sand as well as causes an environmental problem. In this research, the effect of leachate on the dynamic behavior of sand has been studied and the results were compared with clean sand with different saturation degrees. The modified split molds at 50 mm diameter and 100 mm height were used to prepare the leachate-contaminated sand. Both contaminated and clean sand samples were prepared by dry pluviation method. After preparation, the sand samples in the modified mold were put in the leachate wastewater to keep for different cure times. Then they were installed on the dynamic triaxial test system at 0.1 Hz and the same cyclic stress ratio. During the saturation process to prevent the structure of contaminated sands from being disturbed, samples were not passed through CO2 and distilled water. Stress-controlled cyclic tests were conducted at on both clean and contaminated sand consolidated at 100 kPa isotropically. After consolidation phase the measured B values varied between 0.45-0.93. Results show that leachate-contaminated sands are more liquefiable depending on cure time at the same saturation value and saturated clean sand samples and partially saturated leachatecontaminated sand samples show similar liquefaction behavior under the same cyclic ratio.

Understanding the effects of permafrost degradation through a multiphysics approach

Permafrost is a multiphase porous media that can host matter in all three states (solid, liquid, and gas). The equilibrium between the states of matter within the pore space is largely driven by salinity, pressure, and temperature. The complex interactions between the different thermodynamic processes can lead to a complex pore system that is altered at each subsequent thaw and freeze cycle. The dynamic changes imposed on this porous media alter the mechanical and electrical properties of the samples. These changes can thus be quantified and monitored using ultrasonic and electrical resistivity measurements. The experimental results presented in this work document the impacts of a thawing event on unconsolidated quartz sand samples that are partially saturated with a brine solution. The electrical resistivity and ultrasonic data are acquired simultaneously throughout the experiment, and the spatiotemporal changes within the solid matrix are captured by time-lapse X-ray computed tomography (CT). A total of 39 different samples are investigated. The two independent variables chosen for this study are the grain size and the salinity of the brines. The results indicate a clear transition in electrical and elastic properties as the material in the pore space transitions between two different states. Further results indicate that these transitions are the result of the alteration of the pore network itself. In addition, the study of P-wave velocity, ice fraction, and X-ray CT of two different types of ice that coexist within the pore network is documented. Given the distinct impact of two different types of ice on this cryogenic porous media, it is imperative to thoroughly comprehend the existence of different ice types before undertaking the electroelastic investigation of permafrost.

Radiological hazards assessment of building materials used in Swakopmund, Namibia

A Canberra coaxial High Purity Germanium (HPGe) gamma-ray spectrometry detector was used to measure activity concentrations of radionuclides in commonly used building materials in Swakopmund, Namibia. The activity concentrations in, Bq.kg−1, for 226Ra, 232Th and 40K in all sample groups of building materials (cement, sand, cement bricks and roof tiles) were found to be in the range of 18.002–499.266, 14.069–132.508 and 162.794–1747.260, respectively. The average activity concentration of 40K was found to be two times higher than the critical level of 500 Bq.kg−1 in sand, cement bricks, clay bricks and roof tiles. The measured activity concentrations were used to estimate average dose rates and radiological hazard parameters. The absorbed dose rate (D) both due to indoor and outdoor exposure was higher than the international acceptable safe limits in all sample groups while the annual effective dose equivalent (AEDE) due to indoor exposure was higher in sand, cement bricks and clay brick samples. AEDE due to outdoor exposure was within acceptable safe limits for all sample groups. Radium equivalent (Raeq), external hazard (Hex) and gamma (Iγ) hazard indices were found to be higher than the acceptable safe limit only in clay bricks samples. The internal hazard (Hin) index was only higher than the acceptable safe limit in cement and clay bricks while the alpha (Iα) index was higher in sand, cement bricks and clay bricks. The Excess Lifetime Cancer Risk (ELCR) exceeded the acceptable safe limits in all sample groups. Our study showed that most of the computed radiological parameters were significantly higher than prescribed safe limits in most of the samples and therefore may pose a health risk to the inhabitants of Swakopmund.

Formation of secondary microplastics during degradation of plastics originating from the MV X-Press Pearl maritime disaster

AbstractThe MV X-Press Pearl maritime incident had a profound impact on the marine and coastal ecosystems along the west coast of Sri Lanka. Considerable quantities of plastic pellets, specifically nurdles or pellets measuring less than 5 mm and estimated at 1680 tonnes, were released into the Indian Ocean. A notable portion of these plastic pellets/primary microplastics (MPs), has the potential to degrade into secondary MPs. The objective of this study was to investigate and understand the degradation process of plastic pellets into secondary MPs under the extreme conditions of fire and exposure to chemicals during the MV X-Press Pearl maritime disaster. Beach sand samples were collected from 40 locations along the affected west coast of Sri Lanka, at both mean sea level and the berm. An additional 20 samples were collected for a background study covering the entire coastline of Sri Lanka. The Wet Peroxide Oxidation (WPO) process was employed to separate microplastics, and observations of secondary MP quantities were recorded. Fourier Transform Infra-Red Spectroscopic (FTIR) analysis was carried out to identify functional groups of MPs. The variance in average values of secondary MPs at mean sea level (large MPs (i.e. size &gt; 0. 5 mm) = 33 ± 56 items per 1 mm2 and total MPs (i.e. observed through microscope under 40× magnification) = 61 ± 66 items per 1 mm2) and the berm (large = 61 ± 154 items per 1 mm2 and total MPs = 106 ± 165 items per 1 mm2) suggested significant dispersal of large quantities of MPs to other areas in the Indian Ocean with oceanic currents. The baseline average value of secondary total MPs in other coastal areas of the country was approximately 53 ± 66 items per 1 mm2. The positive correlation between large and total secondary MPs and plastic pellets pollution index indicates that a considerable amount of plastic pellets were degraded into secondary MPs within 6 to 8 days after the accident, under the influence of nitric acid and heat/fire. These secondary MPs are mainly composed of low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE), as identified by FTIR observations. Consequently, these lightweight polymers have the potential to spread across a wider region, posing a severe environmental threat on a global scale as a transoceanic marine pollutant.

A review of naturally occurring radioactive elements in coastal regions of Bangladesh

Extensive and systematic study has been carried out globally to get a thorough understanding of the underlying dynamics of radionuclides in the environment. This study was aimed to examine the natural radioactivity level in coastal areas of Bangladesh by combining the main research carried out on environmental radioactivity, predominantly employing established nuclear methods and methodologies during the past. The concentrations of important radionuclides, including 226Ra, 232Th, 40K, 238U, and 235U, were measured in those investigations. Soil samples showed the highest concentration of 226Ra at Inani Beach, Cox's Bazar (21°8ʹ N latitude, 92°4ʹ E longitude), with a value of 61.66 Bqkg-1. On the other hand, Cox's Bazar Sea Beach has the lowest 226Ra concentration at 10.8 Bqkg-1. In contrast, Cox's Bazar had the highest 226Ra activity in the sand and silt samples (147.93 Bqkg-1), whereas Kuakata Sea Beach (21° 48ʹ N latitude and 90° 10ʹ E longitude) had the lowest (2.82 Bqkg-1). The research found that 226Th activity varied from 1085.99 Bqkg-1 to 27.4 Bqkg-1 in soil samples from Cox's Bazar Sea Beach. In Cox's Bazar, the sand and silt samples showed the highest 226Th activity at 1085.9 Bqkg-1. In contrast, Kuakata Sea Beach has the lowest radioactivity at 9.22 Bqkg-1. Soil samples showed that 40K content was highest at Inani Beach (21°13ʹ N latitude and 92°3ʹ E longitude), Cox's Bazar (1304.11 Bqkg-1) and lowest at Cox's Bazar Sea Beach (25.16 Bqkg-1). The sand and silt sample from Kuakata Sea Beach had the greatest 40K activity, measuring 852 Bqkg-1. However, the sample from Cox's Bazar Sea Beach had the lowest amount (21.9 Bqkg-1). Soil samples from Cox's Bazar Sea Beach showed 238U activity of 455.99 Bqkg-1 and 110.84 Bqkg-1, respectively. The highest 238U activity sand sample was found in Cox's Bazar, measuring 460.5 Bqkg-1. The Patenga region (22°14ʹ N  latitude and 91°47ʹ E longitude) in Chattogram has the lowest radioactive level, 45.2 Bqkg-1. The study's findings have been meticulously recorded as crucial foundational knowledge for forthcoming investigations on radionuclides in this coastal area. A comprehensive evaluation of prior published analyses of naturally occurring radioactive elements in the coastal regions of Bangladesh has shown that the level of activity is completely non-hazardous. The experimental areas' soils are ideal for a variety of agricultural and other purposes. Bangladesh J. Nuclear Agric, 37(2): 135-152, 2023

Chromene-chromene Schiff base as a fluorescent chemosensor for Th4+ and its application in bioimaging of Caenorhabditis elegans

The manuscript presents the synthesis of a new di-chromene Schiff base (COM-CH) by combining 7-(diethylamino)-2-oxo-2H-chromene-3-carbohydrazide and 4-oxo-4H-chromene-3-carbaldehyde, and its characterization using various analytical techniques. The probe COM-CH functional group contains a hard donor atom that selectively complexes with Th4+ ions. This report investigated COM-CH's sensing ability towards Th4+ chromogenic and fluorogenic methods in ACN: H2O (8:2, v/v) with Th4+ ions. The COM-CH-Th4+ complex was excited at 430 nm, resulting in a bright emission band at 475 nm with a 45 nm Stokes shift. The COM-CH probe demonstrated the highest performance at pH 4.0 to 8.0, with a sensitivity of 18.7 nM. The complex formation of COM-CH with Th4+ was investigated using NMR, FTIR spectrometry, and density functional theory calculations. The COM-CH and Th4+ are bound with 2:1 stoichiometry and an association constant of 1.92 × 108 M−2. The probe's performance enabled the analysis of monazite sand and water samples for Th4+ content. The probe successfully detected Th4+ content in Caenorhabditis elegans, marking the first Th4+ detection in animal models.

Experimental study on dynamic angle of repose formation: Effect of granular type and water content

The experiment of granular in rotating cylinder is a common experiment to study granular material behaviour. In this study, we investigate the effect of granular type and water content on the dynamic angle of repose in a rotating cylinder. Rice seed, mung bean, and sand are used as samples. Experimental results show each sample has a different dynamic angle of repose that is related to the shape of the sample. We also study the effect of the water content on the sand sample. The addition of water content has no significant effect on the dynamic angle of repose. This occurs because the water content used has passed the critical point.

Applicability of waste foundry sand stabilization by fly ash geopolymer under ambient curing conditions

Recently, utilizing industrial waste in the construction industry has gained significant attention to meet sustainability demands and mitigate the adverse environmental impacts caused by the construction industry. This study evaluates the engineering properties of waste foundry sand as a target material after stabilization with an environmentally friendly stabilizing agent (fly ash geopolymer), focusing on achieving adequate strength under ambient curing conditions as a feasible choice for road bases in geotechnical applications. While fly ash geopolymer application is typically linked with temperature curing, this research explores its application under ambient curing to enhance feasibility and reduce production costs. The fly ash geopolymer was synthesized by activating fly ash using a combination of sodium hydroxide and sodium silicate. The experimental program investigated the geopolymer-stabilized waste foundry sand at varying dosages of 7, 15, and 25 %, examining physical properties, non-destructive tests, mechanical properties, XRD phase analysis, and SEM observation. The results demonstrated that increasing fly ash dosage significantly enhanced the physical properties, mechanical properties, and microstructure of the geopolymer-stabilized waste foundry sand samples. Dry density improved from 1.75 to 2.02 g/cm3; longitudinal wave velocity increased from 897.3 to 2028.4 m/s, and unconfined compressive strength rose from 109 to 5261 kPa. Notably, only samples with 25% fly ash achieved the requisite strength to satisfy the road base limit (4100 kPa). These outcomes instill confidence in the potential use of waste foundry sand as a construction material and transition it from mere filling material to a valuable resource, furthermore encouraging the adoption of fly ash geopolymer as an environmentally friendly stabilizing agent in geotechnical applications.

Examining the socio-ecohydrological status of St. Martin's Island in Bangladesh

One of the most popular tourist destinations is St. Martin's Island, which features a unique state of the socio-ecological environment of Bangladesh. However, tourists, other outsiders, and the island's growing human population significantly influence the overall standard of the socio-ecological environment, which is narrowly described in existing literature. The research aims to assess the state of the socio-ecological environment, particularly the quality of water, soil,flora and fauna, housing, economic activities, cropping pattern, and key degradation of the island. A questionnaire survey was used to assess housing patterns and ownership, drinking water sources, pollutants, vegetation, cropping patterns, and environmental issues. Furthermore, water samples from coastal regions and tube wells were obtained from 138 sampling points examined in the renowned laboratory of leading Bangladesh Council of Scientific and Industrial Research (BCSIR). Measurements were made of five physiochemical parameters such as pH, Total Dissolved Solids (TDS), Electrical Conductivity (EC), arsenic, and chlorine. The profile-based soil and sand samples were assessed based on Organic matter, Total Soluble Salt, pH, and CaCO3. The study found the saltwater along the coast of the island had a range of electrical conductivity from 371 to 7830, TDS from 194 to 8692 ppm, Cl concentration from 0.50 to 2.49 mg/l, arsenic content from 0.00 to 0.49, and pH from 5.50 to 8.09. The findings indicate that semi-brick accounted for 40% of the settlement while brick made up 19.7%, and 37.9% of the settlement was used for residential purposes, and 34.8% of it was made up for commercial purposes (e.g., hotels, resorts, restaurants etc.). Most hotels and residential areas used tube well water, and the study found that pollution from nearby and distant communities was the major cause of the environmental deterioration on island.

Occurrence, distribution, and composition of black sand along the Red Sea, Egypt

Black sand along the Red Sea is often composed of volcanic minerals and heavy minerals. The Red Sea region is known for its unique geological features, and black sand beaches can be found in various areas along its shores. The study presents a comprehensive semi-quantitative chemical analysis of black sand samples collected from various locations along the red sea, revealing significant variations in their elemental compositions. The main oxides were identified in each sample, determined through X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses, indicate diverse mineralogical compositions. The spatial distribution of minerals at each site is depicted through mapping. Additionally, Fourier-transform infrared (FTIR) spectra offer information on the functional groups present in the samples, revealing the existence of hydroxyl groups, aliphatic compounds, and adsorbed water molecules. For Qusier-Elsharm Alqbly, Safaga, Marsa Alam, Gabal Alrosass, Hurghada Titanic, Hurghada Elahiaa, Gemsa, and Ras Elbehar samples, the results highlight the presence of various minerals, such as Quartz, Calcite, Titanium Dioxide, Magnetite, Hematite, Aluminum Oxide, Zirconium Dioxide, Chromium (III) Oxide, and others, providing insights into the geological characteristics of each location. The differences in mineral content among the examined sites are linked to the geological and mineralogical makeup of the source rocks upstream and midstream in the basins that discharge into the surveyed regions. So, variations in black sand concentrations among different locations offer insights into the geological and mineralogical diversity of the studied areas along the Red Sea coast. This study addresses the existing knowledge gap by focusing on the preliminary exploration and description of the occurrence, distribution, and composition of black sand along the Red Sea in Egypt. whereas the results provide valuable insights into the geological diversity of black sand deposits in the surveyed areas, underscoring the need for additional research and interpretation of these variations. Therefore, the in-depth examination of mineralogical composition and crystal structures establishes a foundation for future investigations in the field of geology and earth sciences.

Measurement of the Optical Constants of Sand Samples Using Ellipsometry on Sand-Adhesive Composites.

In order to model the propagation of light through a sand cloud, it is critical to have accurate data for the optical constants of the sand particles that comprise it. The same holds true for modeling propagation through particles of any type suspended in a medium. Few methods exist, however, to measure these quantities with high accuracy. In this paper, a characterization method based on spectroscopic ellipsometry (SE) that can be applied to a particulate material is presented. In this method, a polished disc of an adhesive compound is prepared, and its optical constants are measured. Next, a mixture of the adhesive and a sand sample is prepared and processed into a polished disc, and SE is performed. By treating the mixture as a Bruggeman effective medium, the optical constants of the particulate material are extracted. For verification of the proposed method, it is first applied to pure silica powder, demonstrating good agreement between measured optical constants and literature values. It is then applied to Arizona road dust, a standard reference material, as well as real desert sand samples. The resulting optical constant data is input into a rigorous scattering model to predict extinction coefficients for various types of sand. Modeling results are compared to spectroscopic measurements on static sand samples, demonstrating good agreement between predicted and measured spectral properties including the presence of a Christiansen feature near a wavelength of 8 µm.