Sand Volume Research Articles

Behavior of concrete beams internally cured with clay brick waste

AbstractIn this research, the long-term potential cracking of normal concrete internally cured with clay brick waste as a sustainable approach was investigated. 10% and 15% volume of sand was substituted with corresponding quantity of pre-saturated clay brick waste to enhance the hydration of cement and improve properties of concrete. Four beams internally cured were compared with two control beams. The use of clay brick waste can improve the compressive and splitting tensile strength and also a significant reduction in cracks were observed. Depending on the recorded results, it is demonstrated that the exemplary percentages of clay brick waste to natural fine aggregate was found to be 15%, which developed greatest compressive and splitting tensile strength, and reduce the crack by means of flexural test.

New techniques for the energy saving of sustainable buildings by using phase change materials

Efficiency and energy system improvement are among the main important modern studies centered the energy consumption reduction and thermal performance enhancement of buildings. The main objective of this study is saving the energy of sustainable buildings by using paraffin wax as phase change materials (PCMs) and pumice fine aggregates (PUs) with concrete hollow blocks (CHBs) by using the cement mortars into the walls and ceilings (CILs). The effects investigated on temperature reduction and their role is improving thermal performance, thermal comfort, and electrical consumption energy savings of buildings. Eight concrete hollow blocks CHBs specimens were prepared using the cement mortars. The first group consists of four specimens included CHBs (Standard; without mortar) and the other three mixtures with different percentages of PCMs (0%, 50%, and 75%) by volume of sand. The second group was prepared using PUs aggregate that consists of three CHBs specimens with different percentages of PCMs (0%, 50%, and 75%) by volume of PUs, that prepared to investigate the effects of PUs aggregate and PCMs replacement on the thermal properties. The eighth CHBs specimen was filled with pure PCMs. The thermal properties of the prepared specimens were performed by Differential Scanning Calorimetry (DSC), thermal Conductivity (K- Value), and heat transfer evolution (HTE) analysis technique. Four rooms were built with a 6 cm ceiling thickness and CHBs walls, to study the effect of PCMs and PUs on the thermal properties. The temperature evolution in the rooms and the offset peak hours, cooling load, and energy cost savings were investigated. Results indicate improving the thermal properties of the tested specimens. The room results show a decrease in the indoor temperature of the room with 5.75 °C. The cooling load reduction was 26%, corresponding to an electricity consumption savings of approximately $2.76/Day m3. Based on all results, thermal performance tests showed that the modal room with the PCMs + PUs can be improved thermal comfort keeping the indoor temperature at the comfortable range for a large time and reduced the electrical consumption energy of buildings.

In vitro Propagation and Caulogenesis of Dracaena draco Plants

Dracaena draco is a monocot from family Asparagaceae. The dragon tree is a subtropical plant and features many botanic and Mediterranean gardens worldwide. D. draco has been categorized as vulnerable in Europe and endangered worldwide in the IUCN Red List of Threatened Species (IUCN, 1998). The aim of this study is to develop an efficient protocol for rapid in vitro propagation and caulogensis of D. draco Plants via enhanced axillary bud proliferation from single nodal explants cultured on full strength MS medium, 30g/l sucrose, 4g/l gelrite augmented with various concentrations of plant growth regulators as BA, NAA, IBA and their combinations. In general, the present study concluded that the best results for the initiation stage were recorded on MS medium fortified with NAA and BA at 2.00 and 1.00 mg/l, respectively. Meanwhile, supplemented medium with BA and NAA at 4.00 and 1.00 mg/l, respectively, gave rise to the best results for the multiplication stage. Regarding rhizogenesis stage, the best results were recorded when the neoformed shoots of the multiplication stage were divided singly and cultured on MS medium plus IBA and NAA at 1.00 and 0.50 mg/l, respectively which led to the highest mean number of roots formed per propagule. For callus induction, the internodal segments cultured into MS medium supplemented with BA and NAA at 0.50 and 2.00 mg/l, respectively, gave rise to the best results for the percentage of explants formed callus and callus size. Concerning the percentage of direct organogenesis and number of shoots formed per explants best results obtained from BA and NAA at 0.250 mg/l and 0.00 mg/l, respectively.Neoformed plantlets were acclimatized ex vitro and in vivo vigorously in a mixture of perlite and peat moss at (1:1) or (2: 2) or (2:3) and (3:3) consecutively, in addition to fixed volume (1 portion) of sterile sand; which resulted in the highest mean value of survival percentage/plant (100%) and showed true-to-type plants ex vitro.

Geomechanical modelling of cold heavy oil production with sand

Abstract The contribution of geomechanics to provide a rigorous quantification of porosity changes and associated permeability changes is often neglected when considering hydrocarbon production. However, it often has significant effects on production rates and ultimate recovery. For the cold heavy oil production with sand (CHOPS) technique, geomechanics is the key for reservoir simulations and promoting successful operations. In fact, the technique employed in CHOPS significantly affects the stress state within the reservoir by inducing “on-purpose” formation damage. It is not only vital to comprehend the behaviour of the reservoir during production, but it is crucial to identify how to harness that behaviour to improve productivity. In order to simulate the mechanical behaviour of unconsolidated sand material, an elastoplastic damage model was formulated. Fluid-flow-geomechanical modelling was then performed for predicting individual well behaviour and overall field performance. The combined effect of fluid-flow and geomechanics improved predictions with respect to oil, water, and gas production rates at key wells. Fluid rates matched satisfactorily most of the wells. In addition, the onset and propagation of equivalent wormhole networks were quantified throughout the production history. This enabled quantification of the volume of produced sand at individual wells. The comparisons between the measured and simulated sand volume rate at well locations showed reasonable agreement. Such calibrated models can then be used for the placement of new wells to optimize production.

Erosion-deposition dynamics and long distance propagation of granular avalanches

Abstract

Utilization of Ash from Municiple Solid Waste to Improve Physical - Mechanical Properties and Reduce of Cost Material in Manufacture of Batako

Municipal solid waste processing is an important issue in every country, including Indonesia. The incineration treatment can minimize the volume of waste and produce heat and residue (ash). Ash produced can reach 10-20% of the initial volume of waste. This study was trying to reuse the ash resulted from the incineration of municiple solid waste to making of batako, which have an added value. The study of batako making used a mixture of ash from incinerators, sand and cement. Mixing composition of normal brick raw material is 25% by volume of cement and 75% by volume of sand. The addition of ash from the incinerator is done to substitute a portion of the volume of sand, which is varied as much as 10%, 20%, 30%, 40% and 50% by volume of the amount of sand used. All the raw materials were homogenously mixed and added 20% water from the total volume of material, and added 20% water from the total volume of material, then formed by pressing and followed by drying at room temperature for 14 days. The samples of batako were characterized for its density, water absoption and compressive strength. Based on the test results show that the density value tends to decrease and conversely the value of water absorption tends to increase with the increasing number of ash compositions. The concrete compressive strength value tends to increase significantly from the composition of ash 10% to 40%, but at the addition of 50% ash, the compressive strength value tends to be the same as samples using 40% ash. From the results of this study an optimal composition was obtained in a sample with 40% ash which has the characteristics of density = 1.68 g / cm3, water absorption = 18.89% and compressive strength =85.88 kgf/cm2

Full Loop Numerical Simulation of Fluidization Characteristics at Cyclone and Furnace of 110 MW CFB

Circulating fluidized bed (CFB) boiler has strong points with its recognition when operating with low quality coal contrast to pulverized coal boiler. Boiler load could be improved by increasing coal input and air ratio combustion adjustment. That is why ratio combustion between secondary and primary air is one of valuable parameters influencing fluidization of CFB Boiler. CFB boiler is consist mainly of a furnace, two cyclones, and forced loop pipes, where cyclones are boiler parts that were indicated to have high velocity fluidization up to 30 m/s. Full loop 3D simulation of CFB with focusing on the furnace and cyclone by using computational fluid dynamic (CFD) program was implemented using Eulerian multiphase model to investigate sand volume of fraction, air, and sand velocity including pressure distribution around Cyclone. Several air ratio combustions between primary and secondary air were simulated such as 55%-45%, 50%-50% with 63%, and 100% load variations. It was shown that operation with air combustion ratio 50%-50% and 55%-45% leads to good fluidization at 63% load, while 100% and 110% fluidization will cause an abundant sand entered to inlet cyclone and induce higher sands and air velocity.

Effects of different proportions of soft rock additions on organic carbon pool and bacterial community structure of sandy soil

The sandy soil leaks water and fertilizer, and the ecological degradation is serious. The structural characteristics of soft rock and sandy soil are complementary, and the improvement of sandy soil by adding soft rock is of great significance to improve soil fertility, restore biodiversity, and maintain sustainable development of the Mu Us sandy land region. In this study, total organic carbon (TOC), particulate organic carbon (POC), dissolved organic carbon (DOC), easily oxidized organic carbon (ROC), microbial biomass carbon (SMBC), bacterial community structure and crop yield were examined using soft rock:sand volume ratios of 0:1 (CK), 1:5 (C1), 1:2 (C2) and 1:1 (C3). Our results indicated that, compared with the CK treatment, TOC (9.66–22.34%), POC (85.65–120.41%) and ROC (114.12–192.31%) noticeably increased in C1, C2 and C3 treatments; SMBC in treatment C3 increased by 42.77%. The three dominant bacteria in the soil (Proteobacteria, Actinobacteria and Chloroflexi), as well as Proteobacteria abundance, greatly declined in the treatments with the addition of soft rock. Pseudarthrobacter was the dominant Genus in all treatments, having an abundance between 11.83 and 19.33%. Bacterial diversity, richness and evenness indices all recorded an increase under the treatments. POC, TOC and SMBC recorded the most significant effects on the bacterial community structure. The largest increases in wheat and corn yields were recorded in the C2 treatment (16.05% and 16.30%), followed by the C1 treatment (8.28% and 8.20%, respectively). Our findings indicate that a soft rock:sand ratio between 1:5 and 1:2 recorded the most improvement in the sandy soil environment.

The influence of incorporating recycled brick on concrete properties

One of the major problems in modern construction is the accumulation of construction and demolition waste; this study thus examines the consumption of waste brick in concrete based on the use of blended nano brick powder as replacement for cement and as a fine aggregate. Seven concrete mixes were developed according to ACI 211.1 using recycled waste brick. Nano powder brick at 0, 5, and 10% was used as a replacement by cement weight, with other mixes featuring 10, 20, and 30% partial replacement by volume of river sand with brick. The experimental results for replacement of cement with nano brick powder showed an enhancement in mechanical properties (compressive, flexural, and tensile strength) at 7, 28, 90, and 180 days for the 10% replacement level, while the mixes with 20% brick sand replacement also showed an improvement in mechanical properties.

Effect of Wetting Conditions on the In Situ Density of Soil Using the Sand-Cone Method

The sand-cone method is commonly used to measure the in situ density of compacted soils. While determining field density with this method, differences in the sand-filling process between the test hole and the calibration container can cause errors. The differences can result from various in situ conditions such as the shape and size of the test hole and the moisture conditions of the filling sand and test ground. Temporary rainfall can increase the moisture content of both in situ soils and filling sand. This study examined the effect of wetting conditions on the accuracy of the sand-cone method in a laboratory. Compacted soils with different water contents (2–16%) were prepared in a small circular container in the laboratory, and the sand-filling process was simulated for cylindrical, conical, and roof-shaped test holes with depths of 10 and 15 cm. As the water content of the compacted soils increased, the sand-cone method underestimated the volume of sand accumulated in the test holes by up to 20%, resulting in the calculated density being overestimated by an identical amount. Slightly moist sand was poured into artificial test holes. When the water content of the filling sand was below 1%, no significant error was observed in the calculated volume.

Structural Behavior of Reinforced Concrete Slabs Containing Fine Waste Aggregates of Polyvinyl Chloride

In several areas worldwide, the high cost and shortage of natural resources have encouraged researchers and engineers to explore the serviceability and feasibility of using recycled aggregates in concrete mixtures, substituting a normal aggregate percentage. This technique has advantages for the environment by reducing the accumulation of waste materials, while it impacts the fresh and hardened concrete performances, reducing workability, flexural strength, compressive strength, and tensile strength. However, most studies have investigated the influence of replacing normal aggregates with waste aggregates on the concrete mechanical properties without examining the impact of using waste materials on concrete structural performance. The aim of this research is to investigate the effect of replacing 75% of sand volume with polyvinyl chloride (PVC) fine waste aggregates on the performance of reinforced concrete slabs. Different thicknesses of the concrete layer (0%, 25%, 50%, and 100% of slab thickness) containing PVC fine waste aggregates are investigated. Based on the reductions in the toughness and flexural strength capacity due to incorporating 75% PVC fine aggregate dosage, two approaches are used to strengthen the slabs with 75% PVC fine aggregates. The first approach is adding polyvinyl alcohol (PVA) to the PVC fine aggregate concrete mix to improve the mechanical properties of the concrete. The PVA increases the water viscosity in the concrete, which reduces the dry out phenomenon. With that said, the PVA modified fresh concrete does enable the use of the limits of the PVC fine aggregate dosage for high dosage plastic aggregate concrete. The second approach uses two fiber wire mesh layers as an additional reinforcement in the tested slab. Results show that the PVC-30 slab exhibits an 8% decrease in total area toughness compared to the control (Con) slab, while for PVC-60 slab toughness, the total area shows 26% less. Additionally, the inclusion of PVA in the concrete with 75% PVC plastic waste fine aggregate replacement greatly influences the pre-and post-cracking ductile performance among other slabs, representing that using PVA with higher contents might increase the flexural performance. Therefore, due to the substantial effect of PVA material on the concrete flexural performance, it is proposed to utilize PVA with an optimum PCV fine aggregate dosage in the concrete mix.

Controls on fluvial meander‐belt thickness and sand distribution: Insights from forward stratigraphic modelling

AbstractFluvial point‐bar evolution commonly involves multiple stages of bar development driven by changes in the style of meander transformations. Complicated planform morphologies are widely recognized in remote‐sensing imagery, but the relationships between meander‐bend evolutionary behaviour and stratigraphic architecture, facies distribution, and sand volumes remain poorly understood. This study applies a geometric forward stratigraphic model (Point‐Bar Sedimentary Architecture Numerical Deduction – ‘PB‐SAND’) to simulate the internal sedimentary architecture of 24 meander‐belt segments that evolved via a broad range of meander‐bend transformation styles. Modelling inputs are constrained by channel trajectories inferred from high‐resolution Light Detection and Ranging (LiDAR) datasets, lithological information from a sedimentological database (Fluvial Architecture Knowledge Transfer System – ‘FAKTS’) and geological knowledge of trends in point‐bar lithology (for example, decrease in sand proportion with sinuosity, downstream of bend apices, and beyond the transition from point‐bar to counter‐point‐bar deposits) and in channel bathymetry (depth variations across pools and riffles). Modelling results are used to explore how the relative distribution of sand and mud is controlled by the styles of point‐bar transformation, quantified by the relative degree of meander translation versus expansion, and by the amount of bend rotation. The 24 models are classified into three groups based on cluster analysis of their mean migration angle, mean apex rotation, mean sinuosity, standard deviation of channel circular variance and preservation ratio; these quantities are known to be controlled by meander transformation types. Quantitative comparisons across these groups and relationships between metrics of planform change and quantifications of point‐bar deposits demonstrate how meander planform evolution controls point‐bar thickness and sand volume. Locally, the thickness of sand in bar deposits is controlled by the interplay of facies trends and spatial variations in bar thickness that reflect bathymetric changes, both related to local hydrodynamics. The proposed workflow establishes linkages between planform morphologies and three‐dimensional facies distributions; it can be employed to characterize the distribution of subsurface porous volumes where the planform history of meander bends can be reconstructed.

Vegetation effects on coastal foredune initiation: Wind tunnel experiments and field validation for three dune-building plants

As the land-sea interface, foredunes buffer upland habitats with plants acting as ecosystem engineers shaping topography, and thereby affecting storm response and recovery. However, many ecogeomorphic feedbacks in coastal foredune formation and recovery remain uncertain in this dynamic environment. We carried out a series of wind tunnel experiments testing how the morphology, density, and configuration of three foredune pioneer dune building plant species influence the most basic stage of dune initiation — nebkha formation around individual plants. We established monocultures of native Ammophila breviligulata and Panicum amarum and invasive Carex kobomugi in 1 m × 1 m planter boxes of sand to simulate approximate natural and managed densities and planting configurations on the US Mid-Atlantic coast. We subjected each box to constant 8.25 m/s wind for 30 min in a moveable-bed unilateral-flow wind tunnel with an unvegetated upwind sand bed. We quantified resulting topography with sub-millimeter precision and related it to plant morphology, density, and configuration. Plant morphology, density, and configuration all influenced the resulting topography. Larger plants produced larger nebkha with greater relief, height, and sand volume. However, nebkha area, height, and planform shape varied among species, and taller plants did not necessarily produce taller nebkha. The erect grasses, Ammophila and Panicum, produced more elongated, high-relief nebkha compared to the low-lying Carex, which produced lower and more symmetrical equant nebkha. A staggered planting configuration produced greater net sediment accumulation than non-staggered. We validated these results against high-resolution field topographies of foredune nebkha and found strong agreement between the datasets. Our results provide species-specific parameters useful in designing foredune plantings and beach management and can be used to parameterize vegetation in models of foredune evolution associated with different plant species. By first understanding the underlying ecogeomorphic feedbacks involved in nebkha formation, we can more effectively scale up to forecast coastal foredune evolution and recovery.

Cross-Shore Profile Evolution after an Extreme Erosion Event—Palanga, Lithuania

We report cross-shore profile evolution at Palanga, eastern Baltic Sea, where short period waves dominate. Cross-shore profile studies began directly after a significant coastal erosion event caused by storm “Anatol”, in December of 1999, and continued for a year. Further measurements were undertaken sixteen years later. Cross-shore profile changes were described, and cross-shore transport rates were calculated. A K-means clustering technique was applied to determine sections of the profile with the same development tendencies. Profile evolution was strongly influenced by the depth of closure which is constrained by a moraine layer, and the presence of a groyne. The method used divided the profile into four clusters: the first cluster in the deepest water represents profile evolution limited by the depth of closure, and the second and third are mainly affected by processes induced by wind, wave and water level changes. The most intensive sediment volume changes were observed directly after the coastal erosion event. The largest sand accumulation was in the fourth profile cluster, which includes the upper beach and dunes. Seaward extension of the dune system caused a narrowing of the visible beach, which has led to an increased sand volume (accretion) being misinterpreted as erosion

Potential use of PET and PP as partial replacement of sand in structural concrete

ABSTRACT The use of polymeric residues in the civil construction has been the target of many studies aiming to reduce the volume of post-consumer plastics in the environment. This work focuses on the viability to use polyethylene terephthalate (PET) and polypropylene (PP) as partial replacement to sand in concrete. PET and PP flakes from post-consumer packings were used as light aggregate to partially replace, individually, 10% in volume of sand. The effect of adding these polymers was investigated in terms of physical, mechanical, durability and morphological properties of the concrete. Physical properties were measured in terms of water absorption, voids content and specific mass. Mechanical properties were measured in terms of compressive strength and elasticity modulus. Durability properties were measured in terms of capillarity water absorption and electrical indication of the concrete to resist to chloride ion penetration. MEV and EDS were used to carry out morphological analysis. DSC curves were carried out to evaluate thermal properties of the polymeric flakes. Contact anlge test was also performed. The partial addition of PET and PP polymers reduced the compressive strength by 20%, whilst the reduction of the elasticity modulus was 16% for PET samples, and almost insignificant for PP samples. The durability results show that the polymers contributed to increase the resistance of the samples to chloride penetration by 15% and 57%, for PET and PP samples, respectively; however, there was an increase in the voids content and water absorption. In the morphological test it is possible to observe a lower interfacial adhesion between PP and the cementions paste in comparison to PET.

Evaluation of main factors affecting fractured horizontal well productivity of tight sand gas reservoir in Sichuan Basin

Hydraulic fracturing horizontal well is the key technology of tight gas development. After fracturing, the gas well shows the characteristics of great difference in production energy and many factors affecting production capacity. Therefore, taking 10 fractured horizontal wells in JQ gas field in Sichuan Basin as an example, comprehensively considering the influence of geological and engineering factors, and based on the statistical analysis of gas well productivity and the laws of various index parameters, 17 geological and engineering parameters were selected, and the main factors controlling productivity were studied by grey correlation method. The results show that the tight gas fracturing horizontal well can obtain high production, which is jointly determined by geological and engineering factors. The five main control factors affecting the productivity of tight gas fracturing horizontal well are as follows: proppant type, preflush, ϕ·h. Sand volume and reservoir volume.

Sudut Tenang Tanah Pasir-Lempung Pada Kondisi Runtuh

The soil layer is the combination of many types as well as the soil in the slope area. The soil in the slope is frequently a mixture of clay and sand. The stability of slope becomes dominantly an issue in the geotechnical engineering area. The collapse of the slope occurs because the gravity of external forces is exceeding the shear strength of the soil. The recent research develops the apparatus to determine the angle of repose of the sand-clay soil in the failure conditions. Sandy soil is taken from Beach and Merapi volcano. The clay added into the sand in the proportion of 0%, 5%, 10%, 15%, 20%, 25%, and 30%. The experiment is conducted by taking the height of the falling material of 15cm, 25cm, and 35 cm. Adding 0% to 15% clay brings the sand into SP Category, then adding 20%-30% makes the sand in the SC category. The Modulus if a fine grain of sand beach is smaller than Merapi sand. As the percentage of clay added to the sand higher, the difference of angle of repose of Merapi sand before and after failure is getting smaller, but it is not the case in Beach sand. The percentage of loss of volume of Merapi sand after failure is also going down as the portion of clay higher. The loss of volume of Beach sand added by clay is getting higher in failure condition..

Effects of Specimen Size on The Compressive Strength of Rubber Modified Self-Compacting Concrete

In the studies carried out until today, rubber-modified self-compacting concretes (RMSCC) had been manufactured by replacing the aggregates of the waste vehicle tires (WVT) in the grain size distribution and particles that have different workability, different mechanical, and physical properties. However, variation of the carrying capacity of the RMSCC elements produced with different slenderness ratio h/b ratio under axial load had not been researched in previous studies. Within the scope of this study, the change in physical and mechanical properties of RMSCC elements produced by using different h/b ratios had been examined both experimentally and theoretically. Since the natural sand and WVT aggregate used in the production of concrete and their grain sizes are in the same range, WVT aggregate has been replaced by natural sand in 4 different proportions. These ratios were used as 5%, 10%, 15% and 20% of the natural sand volume, respectively. Slenderness ratios, h/b ratios were 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5, and experimental and theoretical investigations had been performed for 90 samples in total. The linear regression models of the obtained results had been analyzed and the equations with the h/b ratios according to these models had been produced. The results of the obtained equations and the results of experimental axial pressure had been compared. In addition to the amount of WVT aggregate used and the increase in the ratio of h/b, the compressive strength losses had caused by different rates on the samples. The effect of the WVT aggregate ratio on the compressive strength had become more significant with the increase in use rate. Besides, regression analyzes had been performed to determine the effect of h/b ratio on the compressive strength. In conclusion, regression R2 (coefficient of determination) values that belong to equations obtained had been found over 0.95.

Prediction of ultrasonic pulse velocity in steel fiber-reinforced concrete containing nylon granule and natural zeolite after exposure to elevated temperatures

This study takes the advantage of ultrasonic pulse velocity (UPV) in characterizing the mechanical properties of steel fiber-reinforced concrete (SFRC) containing recycled nylon granule (NG) and natural zeolite. A total of 216 specimens were prepared with 0, 0.75, and 1.25% volume fractions of steel fiber; 0, 10, and 20% of sand volume replaced with NG; and 10, 15, and 20% of cement weight substituted with micronized zeolite. The specimens were then exposed to temperatures of 20, 300, and 600 °C. The effect of each parameter (fiber, NG, zeolite, and temperature) was examined individually on the compressive and tensile strength, as well as the pulse velocity in the specimens. In addition, SEM and EDAX tests were successfully carried out on the specimens to investigate the interfacial microstructures in more detail. The obtained measures were also compared with EN 1994-1-2 and ACI 216 recommendations, and thus, several models were developed in terms of variables under consideration. The results revealed that adding NG to SFRC reduces its mechanical properties, particularly after exposure to elevated temperatures. However, incorporating steel fiber and natural zeolite not only counterweighs the induced reduction but also improves the properties of SFRC as compared to control specimens.

Modeling Sand Shoals on the U.S. Atlantic Shelf: Moving Beyond a Site-by-Site Approach

Pickens, B.A.; Taylor, J.C.; Finkbeiner, M.; Hansen, D., and Turner, L., 2021. Modeling sand shoals on the U.S. Atlantic shelf: Moving beyond a site-by-site approach. Journal of Coastal Research, 37(2), 227–237. Coconut Creek (Florida), ISSN 0749-0208.The demand for offshore marine sands has escalated worldwide as sediments are needed for increasingly frequent beach renourishment and barrier island restoration. Sand shoals are often used as a source for dredging material because of the high volume of sand per unit area. Yet, investigations of shoals are typically conducted on a site-by-site basis, and a broader understanding of shoal availability is needed for strategic decision-making, including the mitigation of ocean use conflicts. Here, the primary objective was to model shoal distribution across the U.S. Atlantic shelf, including the Gulf of Mexico. Publicly available bathymetry data were obtained at a relatively coarse 90-m resolution. Variables of depth, standard deviation of depth, slope, bathymetric position index, and distance to shoreline were used as predictors to identify shoals. Unsupervised classifications of the seafloor were conducted to distinguish shoals and swales. Classification accuracy was assessed with validation databases of identified sand resources and named shoals compared to random locations; a visual assessment was also conducted. Shoals were further characterized by their origin. The classifications showed shoals and swales differed from the seafloor. Shoals were more shallow, had higher slope, a higher standard deviation of depth, were closer to the shoreline, and had a more positive bathymetric position index. Shoals were classified on 4.7% of the U.S. Atlantic shelf, and validation showed a percent agreement of 65–93%. Classified shoals visually coincided with the shape and extent of known sand resources. Shoals were characterized as cape-associated, bedform, isolated shelf, or uncharacterized. For the continental shelf, multivariate predictors represented the heterogeneous sloping substrates and the flat, high relief crests of sand shoals. The ability to classify shoals with 90-m resolution bathymetry data in the U.S. Atlantic reveals the methodology may be applicable to identify sand shoals elsewhere in the world with currently available data.