Sand Research Articles

Flow resistance over heterogeneous roughness made of spanwise-alternating sandpaper strips

The Reynolds number dependent flow resistance of heterogeneous rough surfaces is largely unknown at present. The present work provides novel reference data for spanwise-alternating sandpaper strips as one idealised case of a heterogeneous rough surface. Experimental data are presented and analysed in direct comparison with drag measurements of homogeneous sandpaper surfaces and numerical simulations. Based on the homogeneous roughness data, the related challenges and sensitivities for the evaluation of roughness functions from experiments and simulations are discussed. A hydraulic channel height is suggested as an alternative measure for the drag impact of rough surfaces in internal flows. For the investigated heterogeneous roughness, it is found that turbulent flow does not exhibit a fully rough flow behaviour, indicating that the assignment of an equivalent sand grain height as commonly applied for homogeneous roughness is not possible. A prediction of the drag behaviour of rough strips based on an average between rough and smooth drag curves appears promising, but requires further refinement to capture the impact of turbulent secondary flows and spatial transients linking smooth and rough surface parts. While turbulent secondary flow induced by the roughness strips yield significant spanwise variation of the mean velocity profile for the investigated rough strips, we show that the spanwise averaged velocity profiles collapse reasonably well with a smooth or homogeneous rough wall flow. This allows to extract a global roughness function from the spanwise averaged flow field in good agreement with the one deduced from global pressure drop measurements.

Pengaruh Pemanfaatan Kulit Kerang Sebagai Pengganti Sebagian Agregat Halus dengan Menggunakan Pasir Pantai Terhadap Kuat Tekan Beton dan Mutu K-200

The influences of shells utilization as smooth aggregate replacement by using sands beach on the concrete compressive strength and the quality of k-200, the use of smooth aggregate substitutes, such as manually broken clam shells and beach sand obtained from Paciran, Lamongan Regency. The mixture used in making concrete is concrete with quality K-200 (fc'16.60 Mpa). Concrete sand will be replaced by 50% with beach sand, and mixed variations will be carried out with the addition of shells by 10%, 15%, and 20%. The test results show that the average compressive strength of normal concrete is 16.60 Mpa. For a mixture with shell waste by 10% and sea sand by 50%, the average compressive strength value is 15.09 Mpa. In a mixture with shell waste by 15% and sea sand by 50%, the average compressive strength value is 14.62 Mpa. While in a mixture with shellfish waste of 20% and sea sand of 50%, the average compressive strength value is 14.13 Mpa. The concrete variant with the highest average compressive strength value is the normal variant with a value of 16.60 Mpa, while the concrete variant with the lowest average compressive strength value is the variant with shell waste of 20% and sea sand of 50%, with a value of 14.13 Mpa.

Field Observations of Hydrostatic Pressure Deviations in a Nearshore Sediment Bed

AbstractMomentary liquefaction (ML), an instantaneous loss of effective stress between individual sand grains, is caused by the upward vertical pressure gradient of the excess pore‐water pressure in the sediment during the passage of a wave. Few field experiments have provided detailed observations of vertical pressure gradients within a sediment bed. Here, a novel autonomous pressure‐profiling instrument, the Pressure Stick, was deployed in the surf zone of an ocean beach in Rye, New Hampshire. The Pressure Stick has eight time‐synced absolute pressure sensors distributed over a 70 cm distance to measure absolute pressure in the water column and in the sediment bed. The absence of direct measurements of the sediment‐water interface location and sediment porosity limit direct observations of ML but allow for an examination of the hydrostatic pressure deviations. Observed upward vertical pressure head gradients within the sediment exceed the assumed effective weight of the sediment. Exceedances of two ML thresholds are observed within 16 cm of the sediment‐water interface and consistently occur at the onset of steeper and larger wave crests. Individual waves are characterized with an approximation of the Sleath parameter and the depth normalized wave height. The ML thresholds are exceeded 1%–40% of the time when the Sleath parameter is greater than 0.1 and 1%–33% of the time when the depth normalized wave height is greater than 0.4. These results suggest that wave steepness and nonlinearity may be necessary to induce large vertical pressure gradients that substantially deviate from hydrostatic pressure.

Fossil hailstone imprints in Mesoproterozoic (1.7 Gyr) quartzite of the Tombador Formation (Chapada Diamantina Group), Brazil

Fossil pockmarks, 2.5-4 cm in diameter, 3-8 mm deep, with raised, asymmetrical borders are preserved in Mesoproterozoic quartzite representing fluvial and eolic lithofacies of the Tombador Formation (Chapada Diamantina Group) deposited 1.7 billion years ago in what is now northeastern Brazil. Indentations created by projecting 2-4 cm diameter ice pellets into moist beach sand were of the same type - with raised, asymmetrical borders and equivalent diameters and depths – strongly supporting the hypothesis that the fossil features represent impressions of paleohailstone impacts. These well-defined and well-preserved paleohailstone impressions represent the oldest known features of their type in the world, and the first records from South America.

Morpho-dynamic Induced Rip Currents in Klayar Beach, Pacitan, East Java, Indonesia

Klayar Beach (KB), Pacitan, East Java, Indonesia is a rugged coast with a narrow sand beach, a relatively small embayment with rocky headlands, and a very exotic view as a coastal tourism destination. Despite its attractiveness, KB poses a hazard due to rip currents. From 2009 to 2022, KB visited more than 3 million people, and more than 30 people were reported dead due to drowning in rip currents. This paper presents the result of fieldwork to investigate morpho-dynamic driven rip current hazard of the study area. This study carried out bathymetric and topographic mapping and sediment sampling. The last 10 years’ wave data was used for predicting hydrodynamic parameters. The study shows a good correlation between a variety of incoming significant wave heights and tide fluctuation vs. rip current velocity. The existence of headland plays a significant role in rip current formation in the study area. The headland influences either shadow or deflected rip currents formation for the incoming wave angle. The study also indicates that the type of rip current in the KB is structural boundary controlled, and the most important thing to be alerted for promoting beach safety in this area is that this rip current is predicted permanently to occur.

Construction of Recreation Opportunity Spectrum of River Beach IGS in Mountain City: A Case Study of the Two Rivers and Four Banks of Chongqing

Construction of Recreation Opportunity Spectrum of River Beach IGS in Mountain City: A Case Study of the Two Rivers and Four Banks of Chongqing

Occupancy and detectability of a critically threatened lizard endemic from sandy coastal plains areas of Rio de Janeiro State, Brazil

AbstractLiolaemus lutzae is a small liolaemid lizard critically endangered and restricted to coastal restinga (salty sand dune habitats covered by herbaceous and shrubby vegetation by seaside) habitats of the state of Rio de Janeiro in Brazil. This lizard has been predicted to be extinct by 2080. We studied some of the environmental factors that influence occupancy by the species and detectability by the observer, in addition to investigating which populations remain occupying the areas along its original geographical distribution. We sampled 25 different beach habitats of restinga areas in the state, by 100‐meter replicates of linear transects. The estimated probability of occupancy was 69% (0.69 ± 0.05), and the estimated detectability was 50% (0.50 ± 0.03). The detection model with the best fit contained only the air temperature variable. Occupancy was best described by four variables: number of disturbance sources on the transect, vegetation cover in a 50‐meter buffer, exposed sand cover substrate in a 20‐meter buffer, and built‐up area cover in a 50‐meter buffer. No observations of L. lutzae were made in eight of the 25 restinga areas sampled along the original distribution of the lizard. In seven of these areas, the species had its populations extirpated many years ago, based on the 2007/2008 monitoring data. Conversely, in one area where the species was frequently observed during field surveys and different ecological studies on the species made in last decade, it was not recorded in the present study, indicating a possible recent population extirpation. We recommend that conservation measures be urgently implemented to mitigate anthropogenic impacts on the areas of the remaining populations of this lizard throughout its range, especially preserving the structure and functions of the remaining vegetation of beach habitat along restinga areas.

Pasir Kencana Beach Tourism Management System Pekalongan City

Abstract. One of the tourism potentials located in Pekalongan City is Pasir Kencana Beach which is located in Panjang Wetan Village, North Pekalongan District. Pasir Kencana Beach is approximately ±4km or approximately ±15 minutes from the center of Pekalongan City. This beach has previously attracted a lot of interest from local and out-of-town tourists because of its beautiful sunset views in the afternoon. The Golden Sands tourist location is close to the port, fish auctions and nearby beach tourist attractions so it is very strategic and easy to reach. Pasir Kencana Beach is generally used as a family tourist destination. Golden sand beach used to have an area of beach sand that sparkled like gold, but as sea levels rose or tidal disasters caused the embankments to be damaged, some facilities were poorly maintained and the playground area was submerged when heavy rains arrived, so revitalization or repair of tourist attractions was needed to bring them back to life. Beach tourism can increase the number of visitors and economic growth in the surrounding area.
 In an effort to support the development of the Marine Tourism Area in the Pekalongan City area into an integrated beach tourism destination, a development concept is needed through infrastructure development which includes aspects of Accessibility, Amenities and Attractions (3A). The infrastructure development components include repairing roads to tourist areas, structuring coastal tourist areas which include facilities and infrastructure supporting the area such as: construction of public spaces (rest areas, parking, ticketing, play areas, toilets, landmarks, green open spaces, street furniture, as well as management of drainage, solid waste, waste and others.

Optimization of Urease Amount for Calcite Precipitation in Indian Desert Sand Using Biologically Inspired Method

Optimization of Urease Amount for Calcite Precipitation in Indian Desert Sand Using Biologically Inspired Method

Candida spp. are Largely Alien in Beach Mycosands

Only recently microbial impurity of beach sand has become an essential issue, particularly during the COVID-19 and in the post-Covid period when a large number of beachgoers are infected not only by the virus but also with other microbes. Besides the bacterial and viral microbes, fungal contamination of beach sand has also been studied in detail in the recent past. Although few Candida spp. have been isolated from the beach sand, the growths of common pathogenic Candida spp. like Candida albicans has not been studied so far. In this study, we used two species of pathogenic Candida – Candida albicans and Candida parapsilosis to observe their growth patterns in sea sand. Growths of both species were inhibited in sea sand. It eliminates the possibility of long survival of these species in sea sand and thus their existence mainly appears as surface contamination.

Aerosolized Particulate Matter and Blunting of Ciliary Dynamic Responses: Implications for Veterans and Active Duty Military in Southwest Asia.

Respiratory diseases such as chronic rhinosinusitis and asthma are observed at increased rates in active duty and veteran military members, and they are especially prevalent in individuals who have been deployed in Southwest Asia during Operation Iraqi Freedom and Operation Enduring Freedom. Particulate matter, specifically the fine-grain desert sand found in the Middle East, may be a key source of this pathology because of deleterious effects on mucociliary clearance. With IRB approval, human sinonasal tissue was grown at an air-liquid interface and cultures were exposed to different types and sizes of particulate matter, including sand from Afghanistan and Kuwait. Ciliary dynamic responses to mechanical stimulation and ATP application were assessed following particulate exposure. Particle size of the commercial sand was substantially larger than that of the sand of Afghan or Kuwaiti origin. Following exposure to particulate matter, normal dynamic ciliary responses to mechanical stimulation and ATP application were significantly decreased (P < .01), with corresponding decreases in ATP-induced calcium flux (P < .05). These changes were partially reversible with apical washing after a 16-h period of exposure. After 36 h of exposure to Middle Eastern sand, ciliary responses to purinergic stimulation were completely abolished. There is a neutralization of the dynamic ciliary response following chronic particulate matter exposure, similar to ciliary pathologies observed in patients with chronic rhinosinusitis. Aerosolized particulate matter endured by military personnel in the Southwest Asia may cause dysfunctional mucociliary clearance; these data help to explain the increased prevalence of respiratory pathology in individuals who are or have been deployed in this region.

Simulation of Screening Performance of Linear Vibrating Screen for Sand Sorting Based on Discrete Element Method

Screening technology has been widely used in the grading of granular materials, in order to improve the screening efficiency and screening quality of sand particles, a linear vibrating screening device was designed. Analyzing the motion state of the vibrating screen, it is found that the factors affecting the screening efficiency and screening quality, mainly include: vibration frequency, amplitude and screen surface inclination angle. Taking sand grains as the research object, the Hertz-Mindlin with JKR contact model was chosen to analyze the influence of individual factors on the screening performance, and the discrete element method was applied to simulate and analyze the screening process of the material, and the screening efficiency of the material was used as a measure to obtain the vibration parameter set of the optimal screening performance. It is found that the best vibration parameter set of linear vibrating screen is: vibration frequency f=25Hz, amplitude A=4mm, screen surface inclination angle φ=4^°, at this time the screening efficiency can reach 95.77%. This study proves that the discrete element method has good reliability for the screening of particles, and it can be used to carry out efficiency analysis in the pre-production stage of the screening device, and provide corresponding reference for the design and parameter optimization of the vibrating screen.

Mineralisation of CO2 in wood biomass ash for cement substitution in construction products

This study extends our exploration of the potential of biomass ashes for their CO2-reactivity and self-cementing properties. The ability of three hardwood-based biomass ashes to mineralise CO2 gas and partially replace CEM I in mortars was investigated. The three hardwoods were English oak (Quercus rober), English lime (Tilia x europaea), and beech (Fagus sylvatica). The woody biomass wastes were incinerated at 800°C to extract their key mineral phases, which are known to be reactive to CO2 gas to form carbonates. The selected biomass ashes were analysed for their CO2-reactivity, which was in the range of 32–43% (w/w). The ashes were used to replace CEM I at 7 and 15% w/w and this “binder” was mixed with sand and water to produce cylindrical monolithic samples. These monoliths were then carbonated and sealed cured over 28 days. The compressive strength, density and microstructure of the carbonate-hardened monoliths were examined. The ash-containing monoliths displayed mature strengths comparable to the cement-only reference samples. The CO2 uptake of oak containing monoliths was 7.37 and 8.29% w/w, for 7 and 15% ash substitutions, respectively. For beech and English lime they were 4.96 and 6.22% w/w and 6.43 and 7.15% w/w, respectively. The 28 day unconfined compressive strengths for the oak and beech ashes were within the range of ~80–94% of the control, whereas lime ash was 107% of the latter. A microstructural examination showed carbonate cemented sand grains together highlighting that biomass ash-derived minerals can be very CO2 reactive and have potential to be used as a binder to produce carbonated construction materials. The use of biomass to energy ash-derived minerals as a cement replacement may have significant potential benefits, including direct and indirect CO2 emission savings in addition to the avoidance of landfilling of these combustion residues.

The Impact of Relocation Policy on the Quality of Life of Residents in the Yellow River Beach Area

Background and Aim: The Relocation Plan for Residents of the Yellow River Beach Area in Shandong Province has yielded positive outcomes, but the relocation process also entails significant changes in agricultural production methods, adjustments in family economic structures, reconstruction of rural political power relations, conflicts, and integration of cultural values, as well as disintegration and reconstruction of social relations. These issues can potentially impact the quality of life of the residents. Materials and Methods: This qualitative research investigates the issues arising from the relocation policy, assesses the effects of the policy, and provides recommendations on enhancing the living standards of residents in the Yellow River beach area. This research involved conducting on-site interviews with 10 villagers and 5 members of a village committee from a village in Caiyuanji Township and a relevant literature review. Results: It was found that the relocation policy for the Yellow River beach area is a positive livelihood policy, as villagers have relocated from dilapidated cottages to modern new communities. However, there remain some challenges, including the high cost of living for farmers, issues related to the division of rights among rural village committees, and conflicts in farmers' values. Conclusion: Thus, this paper offers personal recommendations for the Yellow River Mudflat Relocation Project, including increasing investment in supporting industries for agriculture, promoting correct values among villagers, targeting poverty alleviation efforts, and adjusting the power structure of village committees.

Counterface soil type and loading condition effects on granular/cohesive soil – Geofoam interface shear behavior

Soil – geofoam interfaces have been studied through an extensive experimental program by performing multiple series of interface shear tests using two different granular soils (i.e. beach sand and construction material sand) and one cohesive soil (i.e. bentonite clay) as well as a soil mixture containing 75% sand and 25% clay by dry weight at distinct loading conditions (i.e. normal stresses (σ): 25, 100, 250; low, moderate, high loading conditions, respectively). Using the shear stress versus horizontal displacement curves obtained, some important engineering design parameters including peak shear stress, residual shear stress, interface sensitivity (i.e., peak/residual ratio) and displacement required to reach peak stress have been determined and the variations in those interface mechanical properties as a function of loading condition and counterface soil type have been investigated. It was shown that the peak as well as residual shear stresses increased with an increase in normal stress for all the interface systems tested. Further, the granular soil (sand) interfaces demonstrated relatively larger frictional strengths (both peak and residual) as compared to both the cohesive soil (clay) interface and the sand/clay admixture soil interface. Additionally, the higher the angularity of granular soil particles became, the larger the interface shear strengths (peak and residual), when sheared against geofoams, developed in light of experimental results attained as a result of interface shear tests on different material combinations. For comparison, the detected peak strength at average for the construction material sand, the beach sand, and the sand/clay admixture soil interfaces as compared to the bentonite clay interface were improved 59.8%, 43.4%, and 20.3%, respectively. Additionally, the detected residual strength at average for the construction material sand, the beach sand, and the sand/clay admixture soil interfaces as compared to the bentonite clay interface were improved 53.9%, 28.6%, and 15.4%, respectively.

Morphodynamics of a composite sand-cobble beach in response to extratropical cyclone Fiona and seasonal wave variability

Climate change is driving higher coastal water levels, and models project accelerated future sea-level rise and coastal storm intensification. These dynamics paired with anthropogenic coastal alterations will drive drastic coastal change worldwide. Composite beaches with mixed sediment sizes warrant detailed study as these exhibit complex morphodynamics in response to changing hydrodynamics due to the distinct transport thresholds of different sediment types. This study uses a novel multi-method approach to investigate a composite sand-cobble beach in Atlantic Canada experiencing a shortening seasonal sand-covered period. Hydrodynamic forcing and associated beach changes were monitored over a focused eight-month period, while satellite-based visual imagery and reconstructed wave data were analyzed over longer periods. Results show that intra-annual wave energy changes drive sand dynamics, with reduced summer wave energy facilitating short-term deposition. Long-term positive trends were identified in late spring wave heights, which likely contribute to the shortening sand-covered period. Seasonal dynamics were overwhelmed by extratropical cyclone Fiona, which made landfall on September 24, 2022, generating significant wave heights up to 6.8 m in the bay, mobilizing sediment, and steepening cobble berms. A new index approach based on visual imagery facilitated the investigation of beach sand appearance/disappearance using the relative redness of sand compared to cobble. Finally, the UAV-based surveys yielded high-resolution orthomosaics and LiDAR-based elevation mapping, and highlighted pronounced longshore variability in erosion and deposition during Fiona. The beach mostly recovered to pre-storm conditions in <4 months, which indicates that proposed beach nourishment activities may only experience temporary success. The longer-term results showing a conversion of sand to cobble suggest that loss of sandy beach habitat is likely to increase, even without shoreline migration or coastal squeeze driven by sea-level rise.

Green and durable engineered cementitious composites (GD-ECC) with recycled PE fiber, desert sand, and carbonation curing: Mixture design, durability performance, and life-cycle analysis

While engineered cementitious composites (ECC) exhibit superior properties to conventional concrete, using expensive synthetic fibers and large volumes of cement results in a higher cost and carbon footprint. In this study, in order to enhance material sustainability, a green and durable ECC (GD-ECC) was developed with greener raw ingredients, especially recycled polyethylene (PE) fiber and desert sand, as well as with carbonation curing. The durability properties of GD-ECC were experimentally evaluated, followed by a life cycle assessment of a potential bridge deck application to verify the life-cycle reduction in the carbon footprint of civil infrastructure. The results show that the developed GD-ECC exhibits a tensile strength of 3.3 MPa, tensile ductility of 7.7%, and tight crack width of less than 60 µm. The embodied carbon and cost of GD-ECC are comparable to that of conventional concrete due to the recycled fiber and desert sand. Besides, the reinforced GD-ECC exhibited superior corrosion resistance and was predicted to have a service life double that of reinforced mortar. Finally, the life-cycle assessment of a potential bridge deck application indicated that the life-cycle material cost and carbon footprint were reduced by half when replacing conventional joints with GD-ECC link slabs.

Prediction of Beach Sand Particle Size Based on Artificial Intelligence Technology Using Low-Altitude Drone Images

Coastal erosion is caused by various factors, such as harbor development along coastal areas and climate change. Erosion has been accelerated recently due to sea level rises, increased occurrence of swells, and higher-power storm waves. Proper understanding of the complex coastal erosion process is vital to prepare measures when they are needed. Monitoring systems have been widely established around a high portion of the Korean coastline, supported by several levels of governments, but valid analysis of the collected data and the following preparation of measures have not been highly effective yet. In this paper, we use a drone to obtain bed material images, and an analysis system to predict the representative grain size of beach sands from the images based on artificial intelligence (AI) analysis. The predicted grain sizes are verified via field samplings. Field bed material samples for the particle size analysis are collected during two seasons, while a drone takes photo images and the exact positions are simultaneously measured at Jangsa beach, Republic of Korea. The learning and testing results of the AI technology are considered satisfactory. Finally, they are used to diagnose the overall stability of Jangsa beach. A beach diagnostic grade is proposed here, which reflects the topography of a beach and the distribution of sediments on the beach. The developed beach diagnostic grade could be used as an indicator of any beach stability on the east coast of the Republic of Korea. When the diagnostic grade changes rapidly at a beach, it is required to undergo thorough investigation to understand the reason and foresee the future of the beach conditions, if we want the beach to function as well as before.

Aspects of energy, exergy, economy, and environment for performance evaluation of modified spherical solar still with rotating ball and phase change material

This study explores advancements in solar distillation, introducing a modified spherical solar still with a rotating ball to overcome traditional limitations of low productivity. The study conducted a comprehensive set of experiments in Kafrelsheikh, Egypt (31.1107° N, 30.9388° E) to compare the performance of the modified spherical distiller with that of the conventional spherical solar still. The evaluation encompassed various aspects, including energy, exergy, economic, and environmental dimensions. Key factors investigated within the study encompassed a range of rotation speeds (0.25, 0.5, 0.75, 1, 1.25, and 1.5 rpm), the introduction of a black jute wick material stretched over the rotating ball, and the utilization of a thermal storage material beneath the rotating ball. Two thermal storage materials were investigated with three arrangements (desert sand, copper grits, and mixture of both). The study's findings have unveiled that the optimal rotation speed for MSSS was 0.75 rpm, where the yield was augmented by 40 %. While incorporating wick material enhanced the distillate of the modified spherical distiller by 57 % when operating at 0.75 rpm. The best operating conditions for the modified spherical distiller were operating at 0.75 rpm and using wick and mixture of copper grits and desert sand, where the distillate reported 7160 ml/m2.day versus 3525 ml/m2.day for conventional spherical distiller, which means that the distillate was improved by 103 % and efficiency reached 59.5 %. Moreover, the exergy efficiencies for the conventional and modified spherical distillers at 0.75 rpm with thermal storage material, are 3.1 % and 4.2 %, respectively. Also, the cost of producing one liter of distilled water for conventional spherical distiller, modified spherical distiller, and modified spherical distiller with thermal storage material was determined to be $0.066, $0.043, and $0.024, respectively. Finally, the environmental parameter for modified spherical distiller with thermal storage material amounted to 27.7 tons of CO2 annually. Furthermore, the enviroeconomic parameter (Z') for the conventional spherical distiller and modified spherical distiller with thermal storage material stood at 335 and 365 per year, respectively.

Implications of sand grains’ mobility and inundating area to landslides at different slope angles

Implications of sand grains’ mobility and inundating area to landslides at different slope angles