Sand Granulometry Research Articles

Are there differences in the kinetic parameters of the vertical jump performed by beach volleyball players on different types of sand?

Beach volleyball (BV) is an intermittent sport characterised by short-duration and highly demanding activities with low intensity periods. Establishing if players' jump ability is influenced by sand granulometry is a useful information for sport scientists, coaches and players. This study aimed to assess the possible differences in the kinetics parameters of the vertical jump on different types of sand performed by BV players. Twelve elite female players performed six countermovement jumps (CMJs) in three different surface conditions (fine sand, reference, coarse sand) in a random counterbalanced order (216 jumps). A generalised mixed model approach detected differences for CMJ model in total duration (p: 0.016), eccentric phase duration (p: 0.007), concentric phase duration (p: 0.011), time to peak power (p: < 0.001), time to peak force (p: 0.014), maximum rate force development concentric phase (p: 0.004), maximum velocity (p: 0.028) and peak power eccentric (p: 0.018). Coarse sand decreases the time spent jumping compared to fine sand, without a penalty to jump height. Coaches and athletes should take this information into account to enhance their understanding of practice strategies and game conditions. One might anticipate a faster pace in games played on coarse sand and a slower pace on fine sand.

The baseline for micro- and mesoplastic pollution in open Baltic Sea and Gulf of Riga beach

Microplastic pollution has become widespread, occurring even in areas with low anthropogenic impacts, small human populations, and low tourism intensity. Marine beach sand represents the interface between inland and marine environments and acts like a fingerprint of all the processes happening within the onshore catchment and in the sea, driven by marine hydrodynamic processes. An extensive dataset is required from different coastal ecosystems to understand microplastic pollution. Here, we set the baseline for micro- and mesoplastic pollution distribution in 24 beaches along the Latvian coastline (Northern Europe, Baltic states), filling the existing knowledge gap and contributing to the global understanding of microplastic particles presence, transport, and the processes governing its dynamics. We also highlight citizen science as a fundamental tool to support data collection and raise awareness about microplastic pollution, as samples were collected by up to 250 volunteers during organized campaigns. To improve the understanding of the driving forces responsible for plastic pollution distribution along beaches, we analyzed sand granulometry, sample location, hydrodynamic variables (waves and currents), and tourism/leisure intensity. Our results demonstrate that the semi-closed Gulf of Riga beach environment contains fewer micro- and mesoplastic particles (0.10 particles/kg dry sand) compared to the open Baltic Sea (0.16 particles/kg dry sand). For microplastic size fraction particularly, a separate cluster can be distinguished showing a higher microplastic concentration and greater presence of fibers associated with coarser beach sand in the open Baltic Sea and eastern part of the Gulf of Riga. Recreational activity was not observed to have any statistically significant effect on microplastic distribution. We have concluded that hydrodynamics is an important factor for microplastics distribution and accumulation, but the impacts are of local scale, and results vary significantly among existing studies.

Investigating the Influence of Distributor Type, Particle Size and Rice Husk Percentage on Fluidized Beds through Cold Fluidization Experiments

This work studies a fluidization system through cold experiments by using a mixture of rice husk and sand to investigate three parameters: type of bed distributor (perforated plate and plate with Tuyere-type injectors), sand granulometry (mean diameters of 324 µm and 647 µm) and rice husk mass ratio (from 1% to 10% of rice husk). The results reveal that the perforated distributor plate achieved a lower minimum fluidization velocity. However, the plate with Tuyere injectors generated better mixing, thus reducing possible stagnation points. An increase in the mean diameter of the sand raises the minimum fluidization velocity but also facilitates the formation of preferential channels. As for the rice husk mass ratio, values of over 5% cause stagnation points and preferential channels. It was also found that the relation between minimum fluidization velocity and rice husk ratio follows an exponential behavior, and an equation was developed to better describe their relation.

Effect of dry abrasion treatments on composite surface quality and bonded joints shear strength

In order to enhance the adhesion properties of composites for further use in structural bonding applications, the effect of different surface treatments on flax/epoxy composite surface topography, surface arithmetic mean height (Sa), surface free energy ( γ s ) and composite to composite bonded joints shear strength (τ) was studied in this research. The main goal of this work was to evaluate the efficiency of abrasion surface treatments, such as sandblasting and sanding in enhancing composites’ adhesion quality compared to traditional mechanical surface treatments such as peel ply. Surface topography was evaluated using an optical microscope. Surface arithmetic mean height (Sa) was estimated via a mechanical surfscan. Surface free energy ( γ s ) was determined using the contact angle method along with the two-component Owens-Wendt model. Composite bonded joints shear strength was evaluated using the single lap shear joint test (SLJ). Trials revealed that specimens treated with sandblasting presented the highest composite bonded joints shear strength (τ). These specimens were characterized by a non-homogeneous surface topography, the highest surface arithmetic mean height (Sa) along with the highest surface free energy ( γ s ) and surface free energy dispersive component ( γ s d ).Unlike peel ply, sandblasting and sanding caused fiber exposure at the surface level. Sand granulometry used for sandblasting had an effect on the composite surface quality and its bonded joints shear strength. Linear regression revealed that composite bonded joints shear strength increases with the increase of the surface free energy dispersive component ( γ s d ). Abrasion treatments such as sandblasting significantly enhanced the adhesion properties of the composite compared to peel ply. Yet it did cause some side effects such as flax fiber damage and sand residue. These side effects could be reduced by opting for less harsh abrasive sand and more sophisticated cleaning processes.

Analysis of water droplet penetration in earth plasters using X-ray microtomography

Earth plasters are a very interesting solution for the coating of earthen construction, in terms of embodied energy, technical efficiency, while keeping the hygroscopic properties of the wall, unlike very little permeable coatings, as the cement-based ones. An experimental campaign has been conducted on several earth plasters which differs by their sand granulometry, earth origin and earth to sand ratio, leading to controlled surface topography and bulk properties. A novel X-ray microtomography technique adapted to such material has been relevant to observe directly the penetration of a water damping droplet inside the plaster with the 2D radiograph method, and enhance the understanding of the role of the surface and the bulk structure on it. A 3D scanning method was useful to understand the microstructure of the different samples and analyse their differences in terms of porosity. Two custom-made MATLAB codes have been developed in order to follow the droplet parameters inside the material, such as the spread, the penetration depth and the relative quantity of water along the time. Results show the consistent role of the surface topography on the water inertial penetration, while the penetration rate due to diffusion is directly linked to the bulk properties, and can be assimilated to a classic diffusion solution. The determination of the drying rate in the earth plasters highlights that the plasters which prevent the water to penetrate too deeply are also the ones which dry the slower, leading to a questioning on the role researched in an efficient coating material.

Utilization of Upgraded Recycled Concrete Aggregates and Recycled Concrete Fines in Cement Mortars

Waste concrete is the most predominant constituent material among construction and demolition waste. Current waste concrete recycling is limited to the use of recycled concrete aggregates as a road-base material and less as aggregates in new concrete mixes. Further, the production of recycled concrete aggregates results in the generation of a high amount of fines, consisting mainly of cement paste particles. Hence, this study aims to produce the cement mortars using the upgraded recycled concrete aggregates (sand granulometry) for the total replacement of natural aggregates and recycled concrete fines activated through a thermal treatment method as a partial cement substitution material. Cement mortar specimens were tested for their compressive and flexural strength, density and water absorption performance. The results showed that the combined usage of upgraded recycled concrete sand for total replacement of primary crushed sand and recycled concrete fines as partial cement replacement material is a promising option to produce cement mortars.

Influence of Particle and Grain Size on Sand Filtration: Effect on Head Loss and Turbidity

Sand filtration is an eco-friendly method to treat either drinking water or wastewater ; it requires only natural granular media. It is also easy to use and to maintain ; the only problem they face is clogging that affects filter performance, that can be detected when head loss or turbidity increase. The purpose of this work is to see what are the factors that influence the performance of filter operation, for this, we used a pilot consisting on a circular column filled with sand (from South Algeria), where various parameters were tested; pressure, flow rate, sand granulometry, suspended matters and particle concentration of the water which is filtered. After eighteen weeks of operation, we have found that head loss increases by decreasing granulometry and increasing flow rate, pressure, particle size, and concentration. However, turbidity increases by decreasing particle size and increasing granulometry and particle concentration. Turbidity and head loss have different behaviour towards the same parameter; that is why it is necessary to take them into account in order to find a compromise between acceptable head loss / turbidity for a good functioning of the filter.

Possibility to use waste tire waste in the composition of mixtures for the manufacture of cement blocks

The modern lifestyle has led to an increase in the amount of solid waste in the world, and waste tires are one of the most generated. Annually billions of tons of waste tires are produced, so in this study, we sought to reuse them to make materials for civil construction. For this, a laboratory research was carried out where samples were made in 50 x 100 mm cylinders with traces of 0, 10, 15 and 20% (by weight) of waste, in addition to cement, natural sand and water. The granulometric distribution of waste tires and sand was also carried out. And, with the samples in cylinders, the physical and mechanical properties were evaluated, such as water absorption and apparent density, in addition to the analysis of the mechanical resistance to compression and the modulus of elasticity. The results showed that the granulometric distribution of the tire residue fits as a fine aggregate, similar to the sand granulometry. The water absorption rate of the waste specimens was less than 10%. However, the mechanical resistance decreases proportionally as the amount of tire waste has increased. However, when analyzing the behavior of the stress x strain curves, the specimens containing residues, became more flexible, as they are capable of supporting loads beyond the maximum stress. In this way, the resistance and the ability to absorb energy were increased. We concluded that it is possible to incorporate certain quantities of waste tires in blocks for civil construction, but without a structural function.

Sandblasting parameter variation effect on galvanized steel surface chemical composition, roughness and free energy

The aim of this paper is to investigate the effect of variant sandblasting parameters such as pressure, angle and sand granulometry on galvanized steel surface chemical composition, roughness and free energy for the purpose of increasing its adhesion properties for further use in structural bonding applications. Two sandblasting pressures (5 × 105 Pa, 6 × 105 Pa), two sandblasting angles (75°, 90°), and three glace sand granulometries (200/300, 90/150, 70/110) were tested. Surface chemical composition was evaluated using a scanning electron microscope, surface roughness was measured using a mechanical surfscan and surface free energy was determined using the contact angle method along with the two component Owens-Wendt model. Trials revealed that the sandblasting method has an effect on the surface free energy, wettability, chemical composition and roughness. As the sandblasting pressure and glace sand granulometry increased, the surface average roughness (Ra) increased. Specimens treated with the lowest glace sand granulometry had the highest surface free energy (γst). Glace sand granulometry had a more significant effect on the galvanized steel surface properties than that of the sandblasting pressure and angle. Sandblasting angle variation affected the surface chemical composition and wettability rather than the roughness. Sand residue presented at the level of the treated surface varied according to the sandblasting setting which might have affected the surface free energy and wettability along with the roughness.

Crushed concrete waste influence on dune sand mortar performance. Contribution to the valorization

In the region of South Algeria, there is a significant presence of quality aggregates. However, excessive use of these materials can result in significant environmental impacts. For these reasons, it would be advisable to use other substitute materials such as dune sand and construction waste to preserve these resources and avoid excessive pollution of the environment. The aim of this work is to valorize the concrete waste to make it a useful material to correct the dune sand granulometry, in order to manufacture mortars with satisfactory performances in terms of consistency and mechanical strength. To obtain this objective, a methodology for the formulation of mixtures based on the progressive substitution of dune sand by the studied waste was adopted. Several tests were then carried out to examine the effect of the incorporation of waste on the main properties of the mortar fresh and in the cured state. These characteristics were compared to those of the control mortar (consisting only of alluvial sand, cement and water). The results obtained show that the inclusion of the waste used can improve the workability and compactness of the mortars studied and increase their compressive strengths in the short and long term. Moreover, it has been observed that its incorporation induces a decrease in tensile strength.

The role of grain size and inoculum amount on biocrust formation by Leptolyngbya ohadii

Cyanobacteria are widespread prokaryotic organisms that represent feasible biotechnological tools to set up valid approaches to counteract desertification. Their peculiar physiological traits, and their resilience to abiotic stresses, allow their application on abiotically constrained soils to trigger their stabilization. A successful cyanobacteria inoculation results in the formation of cyanobacterial biocrusts, complex microbial communities characterized by tangled filament meshes imbued in a matrix of self-secreted extracellular polysaccharides (EPS) that keep loose sediments and aggregates firmly in place. However, the capability to form stable cyanobacterial biocrusts is not common to all the species, and a mix of factors can hamper the process, notably inoculum amount, and substrate characteristics.The aim of this work was to assess the influence of inoculum quantity and substrate granulometry on the physical stability of cyanobacterial biocrusts induced by inoculating the strain Leptolyngbya ohadii in a microcosm experiment, under laboratory conditions. After applying three different initial inoculum amounts on two different sand granulometries (medium and coarse sand), we assayed aggregate stability, physical stability and surface hydrophobicity on the resulting biocrusts during a 30-day incubation. Also, the features and the role of the EPS synthesized by L. ohadii were studied following their isolation, characterization, and direct application on the sand. The two EPS fractions produced by the strain, one more soluble and easily released in the surrounding medium (released polysaccharides, RPS) and one solidly attached to the filaments (glycocalyx EPS, G-EPS), were separately tested.Cyanobacterial biocrusts visibly formed in all the microcosms after 15 days. However, we observed a strong effect of sand granulometry in affecting aggregate stability and tensile strength, both of which appeared weaker on coarse sand. A higher amount of initial inoculum was necessary to produce stable biocrusts on coarse sand compared to medium sand. Also, we observed how the inoculation of EPS alone did not sort most of the significant effects that we detected by inoculating the whole culture, pointing at the importance of the action of the cyanobacterial filaments in soil conglomeration. However, a significant increase in physical stability was achieved by inoculating G-EPS on medium sand, suggesting the involvement of this fraction in biocrusts structuration.This work analyzes for the first time the effects of the variable grain size and inoculum amount in the achievement of physically stable biocrusts by cyanobacteria inoculation. The results that we obtained are useful in improving and optimizing the process of biomass preparation and dispersion for future indoor and outdoor studies.

Effect of sand granulometry on the egg hatchling success of the sea turtle Caretta caretta

The environmental characteristics of nesting sites of sea turtles may directly interfere with the egg hatchling success. The objective of the present study was to evaluate the factors that affect the success of hatchling in the nests of the loggerhead sea turtle (Caretta caretta). Data from 37 nests of C. caretta from the coast of Mata de São João, Bahia, northeastern Brazil, were obtained from TAMAR, Sauípe station. Samples of sand were collected in each nest to determine the granulometry. A significant negative relationship was found between the stillborn rate and the fine sand ratio (r2 = 0.119; p = 0.036), indicating that a larger fraction of fine sand had a positive effect on nest hatchling success. The egg laying date also had a significant influence on the rate of stillbirths (r2 = 0.163; p = 0.013), with a trend towards a higher stillbirth rate, the later the laying date of the eggs. There is indication that the transfer of eggs to sites with more favorable characteristics may be considered as a potential alternative to increase the hatchling success rate of C. caretta eggs.

Comparing dune migration measured from remote sensing with sand flux prediction based on weather data and model, a test case in Qatar

This study explores validating and calibrating the wind regime predicted by Global Circulation Models (GCM) on Earth and other planets using optical remote sensing of dune dynamics. We use Spot-5 images to track the migration of 64 Barchan dunes in Qatar using the COSI-Corr technique. We estimate the volume of the dunes using a scaling law calibrated from one particular dune, which was surveyed in the field. Using volume and migration rate, we determine the sand flux from a single dune, QDunes, and scale this estimate to the whole dune field. We compare the measured sand flux with those derived from wind velocity measurements at a local meteorological station as well as with those predicted from ERA-Interim (a Global Circulation Model). The comparison revealed that the wind velocity predicted by ERA-Interim is inappropriate to calculate the sand flux. This is due to the 6-h sampling rate and to systematic bias revealed by a comparison with the local wind data. We describe a simple procedure to correct for these effects. With the proposed correction, similar sand flux are predicted using the local and ERA-Interim data, independently of the value of the value of the shear velocity threshold, u⁎t. The predicted sand flux is about 65% of QDunes. The agreement is best assuming the value u⁎t=0.244 m/s, which is only slightly larger than the value of u⁎t=0.2612 m/s estimated based in the sand granulometry measured from field samples. The influence of the dune topography on the wind velocity field could explain the underestimation. In any case, the study demonstrates the possibility of validating GCM model and calibrating aeolian sand transport laws using remote sensing measurements of dune dynamics and highlights the caveats associated to such an approach.

Impact of Silica Sand Granulometry on Bending Strength of Cores Produced by ASK Inotec Process

Nowadays, constant pressure on enviromental aspects in the foundry industry is calling for an improvement in casting production. The almost not used inorganic binders are coming back to the fore. Into this group, among others, belong binders based on alcali silicate solutions, known as water glass. The new hot-curing binder systems were introduced by different binder manufacturers. In order to compensate dissadvantages of alkalic silicate binder, the systems and processes are working with additives and adjuvants which are contained in a binder itself or added in liquid or powder form to the sand mixture. This paper presents the ASK Inotec process and impact of silica sand granulometry on achieved core mixture strength, which is important from a core production and also from a decoring ability point of view. Experiment was performed in laboratory terms using standard equipment and conditions.

Eficiência de filtros de areia pressurizados na remoção de diferentes tamanhos de partículas da água de irrigação

Resumo:O objetivo deste trabalho foi avaliar a eficiência de filtros de areia com diferentes granulometrias na remoção de diferentes tamanhos de partículas da água de irrigação, bem como a perda de pressão em função da taxa de filtração e da granulometria de areia do leito filtrante. Os ensaios foram realizados com três filtros de um mesmo modelo comercial, testados com diferentes combinações de granulometrias de areia (areia fina, 0,55 mm; média, 0,77 mm; e grossa, 1,04 mm de diâmetro) e taxas de filtração (20, 40, 60 e 75 m3m-2 h-1), e repetidos em três ciclos de filtração de 4 horas (C1, C2 e C3, realizados em 3 dias consecutivos). O filtro de areia avaliado é efetivo na remoção de partículas a partir do tamanho de areia fina (&gt;60 μm). Nesta faixa de remoção de partículas, a influência da taxa de filtração aumenta com a diminuição do tamanho de partícula na água. O aumento na taxa de filtração, associado à diminuição da granulometria de areia, aumenta a eficiência de remoção, mas acentua a perda de pressão com o tempo, o que diminui a remoção das partículas menores ao longo dos ciclos de filtração.

Pseudo-stochastic signal characterization in wavelet-domain

In this paper we present the method for fast and accurate characterization of pseudo-stochastic signals, which contain a large number of similar but randomly-located fragments. This method allows estimating the statistical characteristics of pseudo-stochastic signal, and it is based on digital signal processing in wavelet-domain. Continuous wavelet transform and the criterion for wavelet scale power density are utilized. We are experimentally implementing this method for the purpose of sand granulometry, and we are estimating the statistical parameters of test sand fractions.

Influence of the Cooling Rate on the Morphology of Spheroidic Graphite Obtained by the CO2 Process

The mechanical properties of cast metallic materials are strongly influenced by processing parameters, such as percentage of silicate, sand granulometry, and metallurgical processing. The ductile iron cast produced by the CO2 process depends on variables that determine the behavior of the material in service, such as the cooling rate and chemical composition. This study evaluated the influence of the cooling rate on the spheroidic graphite. In order to determine this effect, a simulation was performed in specimens with 20, 25, and 30 mm in thickness, through the characterization of type, measurement of nodule size, and distribution of nodules. Chemical analysis and mechanical resistance tests were performed. The 25 mm thick specimen showed the best behavior among the three thicknesses evaluated, presenting the formation of many small nodules and a small amount of larger nodules in the center.

Influence of the Cooling Rate on the Morphology of Spheroidic Graphite Obtained by the CO2 Process

The mechanical properties of cast metallic materials are strongly influenced by processing parameters, such as percentage of silicate, sand granulometry, and metallurgical processing. The ductile iron cast produced by the CO2 process depends on variables that determine the behavior of the material in service, such as the cooling rate and chemical composition. This study evaluated the influence of the cooling rate on the spheroidic graphite. In order to determine this effect, a simulation was performed in specimens with 20, 25, and 30 mm in thickness, through the characterization of type, measurement of nodule size, and distribution of nodules. Chemical analysis and mechanical resistance tests were performed. The 25 mm thick specimen showed the best behavior among the three thicknesses evaluated, presenting the formation of many small nodules and a small amount of larger nodules in the center.

Linkages between rocky reefs and soft-bottom habitats: Effects of predation and granulometry on sandy macrofaunal assemblages

The movement of animals and materials among habitats can have an important influence on the structure of assemblages. The nature of such linkages is, however, not always an obvious one. Here we examined the influence of rocky reefs on nearby sandy macrofaunal assemblages. A preliminary descriptive study confirmed the hypothesis that sediment granulometry differs in relation to distance to rocky reefs and so did the macrofaunal assemblage composition, and relative abundance of three of the most abundant taxa, and that this effect was generally consistent among locations. In addition, there was a significant effect of sediment structure on community structure of benthic assemblages. A subsequent manipulative experiment tested, in an interactive way, the effects of predation and sediment grain size in structuring macrofaunal assemblages adjacent to a rocky reef. At the scale of the assemblage (richness and composition), results showed that there was an effect of sand granulometry and distance to the reef, while predation had no effect. Predation affected the abundance of one of the most abundant taxa (un-identified amphipod sp.1) but this effect was consistent adjacent and away from the reef. Sand granulometry had no influence on the numbers of the most abundant taxa, while the abundance of two of these taxa (Catapaguroides timidus and Ervilia castanea) still varied according to distance to the reef. This study adds to the wider literature by suggesting that there can be important movements of materials and organisms from rocky reefs to adjacent soft-bottom habitats but that rock-associated predators and sand granulometry may have a limited influence in structuring the small-bodied sediment infauna close to reefs. This study also stresses the need for caution when ascribing the importance of ecological processes based on descriptive studies alone, even when results seem ecologically logical.

Winter distribution, density and size of Mesodesma mactroides (Bivalvia, Mactracea) in Monte Hermoso beach (Argentina)

The yellow clam Mesodesma mactroides (Deshayes, 1854) is a seasonal migrant that moves in spring to the sandy upper intertidal level. In this paper we analyze the spatial distribution of density and mean shell size of the yellow clam population in Monte Hermoso beach (Argentina) in winter 1995, i.e., three months before the mass mortality occurred in November 1995. Sampling covered 32 km of beach, with a regular design of 22 transects. The major environmental gradient in the beach was determined using principal component analysis (PCA) on the correlation matrix of the environmental data (beach morphology, slope, and sand granulometry). Correlation analysis was used to assess the relationship between the score of a site (transect) on the first and second principal component, and clam mean density and mean shell size. Most of the beach seems to be habitable for clams, their spatial heterogeneity not having been explained by the measured variables since, although the first axis of the PCA has demonstrated an E-W physical gradient, clam density was not in correlation with it. Density was maximum near the piers, even though these are points with high tourist activity. It seems that non-extractive touristic activities do not affect population density but rather mean shell size, probably due to reduction of growth rates. The abundance of the winter population, as compared with the assessment done after the mass mortality of November, strongly suggests that a great part of the population was overwintering in the intertidal fringe.