Carbonate Sand Research Articles

Investigation of the ultimate particle size distribution of a carbonate sand

A series of ring shear tests were conducted to investigate the ultimate particle size distribution of a carbonate sand. The tests were carried out under different stress levels, on three types of specimens: 1) uniformly graded specimens made of dry natural sand 2) remoulded specimens of the crushed sand after first shearing to large strains 3) specimens made of natural sand grains but with the same grading as in (2). The first series of tests on type (1), carried out to very large strains, led to apparently stable gradings, distinct for each stress level. Only limited additional particle breakage could be induced by remoulding the specimens after shearing (type (2)) and subjecting them to more shearing. Tests on specimens created at the apparently stable gradings (type (3)) but from the intact sand particles however led to significantly greater breakage. For the three types a stable, fractal grading was achieved. Analyses of the soil particles’ shape showed that the aspect ratio, sphericity and circularity reach a steady value at large strains, in parallel to reaching a stable grading. The mobilized angle of shearing resistance however was not significantly different in the different types of samples, suggesting the final grading dominates the behaviour.

A preliminary study of carbonate sand stabilization by bio-stimulation based MICP method

A preliminary study of carbonate sand stabilization by bio-stimulation based MICP method

Tensile Strength of Artificially Cemented Sandstone Generated via Microbially Induced Carbonate Precipitation.

Artificially bio-cemented sands treated with microbially induced calcite precipitation are weakly cemented rocks representing intermediate materials between locked and carbonate sands. Variations in cementation significantly affect the strength of sample, particularly tensile stregth. The modes of fracture and the surface characteristics resulting from the indirect tensile strength tests (Brazilian tests) are strongly correlated with the specimen strength and consequently the degree of cementation. This study examines the tensile strength of bio-cemented fine and coarse sands (average particle diameter 0.18 and 1.82 mm, respectively) and investigates failure modes by recording fracture evolution at both sides of specimen and surface characteristics of the reconstructed surfaces. The dimensionless slope parameter provided the best fit with respect to tensile strength while the power spectral density was a good indicator of surface anisotropy. Finally, wavelet decomposition allowed for comparison of fracture surface characteristics of the two sands ignoring the grain size effects.

Controls on Physical and Chemical Denudation in a Mixed Carbonate‐Siliciclastic Orogen

AbstractMixed siliciclastic‐carbonate active orogens are common on Earth's surface, yet most studies have focused on erosion and weathering in silicate‐rich landscapes. Relative to purely siliciclastic landscapes, the response of erosion and weathering to uplift may differ in mixed‐lithology regions. However, our knowledge of weathering and erosion in mixed carbonate‐silicate lithologies is limited and, thus, so is our understanding of the mechanistic coupling between uplift, weathering, and the carbon cycle. Here, we partition denudation fluxes into erosion and weathering fluxes of carbonates and silicates in the Northern Apennines—a mixed carbonate‐siliciclastic active orogen—using dissolved solutes, the carbonate sand fraction, and existing 10Be denudation rates. Erosion generally dominates total denudation fluxes relative to weathering by an order of magnitude. Carbonate and silicate contributions to erosion vary between lithologic units, but weathering fluxes are systematically dominated by carbonates. Silicate weathering may be kinetically limited, whereas carbonate weathering may be limited by acid supply. Carbonate re‐precipitation estimated by comparing ion ratios (Sr, Ca, Na) from rivers and bedrock suggests that up to 90% of dissolved Ca2+ is lost from carbonate‐rich catchments. Corresponding [Ca2+] estimates for the weathering zone are high, likely driven by high soil CO2 partial pressures (pCO2); however, re‐equilibration with atmospheric pCO2 in rivers converts solutes back into grains that become part of the physical denudation flux. Weathering limits in this landscape therefore differ between the subsurface weathering zone and riverine exports, and our findings suggest that carbon cycle models may overestimate the sensitivity to erosion of solute exports (Ca2+ and HCO3−) derived from carbonate weathering.

An investigation of the breakage behaviour of a pre-crushed carbonate sand under shear using X-ray micro-tomography

The breakage behaviour of a pre-crushed carbonate sand sheared within a miniature triaxial loading apparatus is investigated using high-spatial resolution X-ray micro-tomography. Full-field 3D CT images of the sand sample are acquired at different loading stages of the test. This enables the quantitative investigation of the temporal and spatial evolution of soil microstructures throughout the test, including particle size, particle shape and local strains. A particle tracking approach capable of identifying fragments of crushed particles is presented, which allows the identification of different particle crushing modes (i.e., chipping, major splitting and fragmentation) occurring during the shear. Particle breakage is found to exhibit clear localization around the shear band as it develops. Meanwhile, the failure modes of particles crushed during shear are found to be related to their particle-scale characteristics, which include particle size and particle shape. Specifically, particles with a smaller size are more likely to fail in the major splitting mode, while particles with highly irregular shapes tend to fail in the fragmentation mode. The image data and experimental findings presented in this study will be useful to develop and validate advanced approaches for discrete element modelling of crushable soils with realistic particle shape.

PLATYMATCH – A particle-matching algorithm for the analysis of platy particle kinematics using X-ray Computed Tomography

Particle scale mechanisms influence the mechanical behaviour of geomaterials. A better understanding of soil micromechanics will help develop more accurate constitutive models and, by extension, safer and more economic geotechnical design. Sand-grained soils have been widely studied at the particle scale using X-ray Computed tomography and this has revealed important micromechanical behaviour of sands. Clays are least understood and studied at the particle scale. As technology rapidly progresses, to understand clay kinematics, a particle kinematic algorithm to match plate shaped (platy) particles will be required. Current algorithms developed for the matching of quartz and carbonate sand particles may not be suitable, since particle attributes that are strong discriminators of round particles may be less unique on platy particles, due to their extremely small c-axis and the reduced image resolution associated with their smaller size. This study presents, particle tracking of kaolin sample using mica markers and provides a platy soil particle matching algorithm for evaluating platy particle kinematics. After testing a range of alternative particle attributes, it was observed that a combination of particle major axis length, intermediate axis length, and perimeter was a good discriminant of the platy mica particles studied. On this basis, we developed PLATYMATCH, an optimised platy particle matching algorithm that considers a minimised combined normalised error of unique particle attributes within a defined search volume space. The algorithm was implemented such that particle attributes were compared in parallel, rather than sequentially, to avoid filtering out a potential particle match based on a single non-unique attribute. PLATYMATCH was then successfully validated using a compressed mica soil sample.

Engineering properties of the compressibility and crushing characteristics of transitional soils mixed with silicate and carbonate sands

Transitional soils mixed with terrestrial silicate and marine carbonate deposits are commonly found in coastal regions, which have special geological and geotechnical characteristics. This study examines the engineering properties of the compressibility and crushing characteristics of this type of transitional silicate‑carbonate soils. Scanning Electron Micrograph, X-ray fluorescence and laboratory tests were first conducted to identify the physical and mechanical properties of the pure silicate and carbonate soil samples adopted in this study. A total of 54 one dimensional compression tests were carried out for soil samples mixed with varying portion of silicate and carbonate sands by applying increasing loading level, where particle size distribution was obtained post each test to quantify particle breakage. The soil deformation is found to comprise two components that are caused by inter-particle rearrangement and particle breakage. The test results show that particle breakage tends to play a dominant role on the deformation with increasing content of carbonate sand and load level. The series of laboratory tests and the associated interpretations in this paper are expected to provide an improved understanding of the compressibility and crushing characteristics of transitional sediments mixed with silicate and carbonate sands. An equation was proposed to establish the relationship between particle breakage and crushing work, which provides a predictive assessment of particle breakage for transitional soils accounting for varying portion of silicate and carbonate sands.

Experimental Study on the Monotonic and Cyclic Behavior of Carbonate Sand in the South China Sea

Carbonate soils have specific properties that differ from those of siliceous sand. The monotonic and cyclic behavior of carbonate sand from Jinqing Island in the South China Sea was examined by undrained monotonic and cyclic simple shear tests in this paper. The monotonic test results show that the phase transformation state friction angle is 25.7°, and the critical state friction angle decreases from 38.7° to 37.3° due to particle crushing. By comparing the experimental data from the monotonic and cyclic tests, we found that the trend of the peak shear stress ratio with shear strain in each cycle of cyclic tests was close to that of monotonic tests. If the cyclic stress ratio of symmetrical cyclic tests is normalized with the phase transformation strengths obtained by the corresponding monotonic tests, it has a good relationship with the number of cycles at failure and is not affected by the relative density and vertical consolidation stress. The effects of the relative density, vertical consolidation stress and initial static shear stress on the undrained cyclic strength are discussed. Finally, a comparison of the undrained cyclic strength of carbonate sand from different regions shows that different carbonate sands have almost identical undrained cyclic strength under the medium dense state, but significant quantitative differences are observed between these carbonate sands under the dense state.

Expanded clay concrete mixtures and concretes on carbonate sand propertie improvement

Results of researches of properties of expanded clay concrete on carbonate sand, mixtures and concrete, as well as a technique for selecting optimal concrete compositions for monolithic load-bearing and enclosing structures of residential and public buildings and structures are given.

Non-lithifying microbial ecosystem dissolves peritidal lime sand

Microbialites accrete where environmental conditions and microbial metabolisms promote lithification, commonly through carbonate cementation. On Little Ambergris Cay, Turks and Caicos Islands, microbial mats occur widely in peritidal environments above ooid sand but do not become lithified or preserved. Sediment cores and porewater geochemistry indicated that aerobic respiration and sulfide oxidation inhibit lithification and dissolve calcium carbonate sand despite widespread aragonite precipitation from platform surface waters. Here, we report that in tidally pumped environments, microbial metabolisms can negate the effects of taphonomically-favorable seawater chemistry on carbonate mineral saturation and microbialite development.

Evaluation of the shear wave velocity (VS) of an artificial carbonate sand obtained with the use of bender elements test

Carbonate sand is characterized by the presence of fragile grains, which may influence their mechanical response due to the imposed loading; especially cyclic loading. The shear wave velocity (VS) provides relevant information for the design of foundation inserted in this type of soil, which can be obtained from laboratory tests with the use of bender elements (BE). This paper aims to evaluate the VS value of a carbonate sand from triaxial tests with BE using three methods in the time domain. The influence of loading, unloading and cycling on VS is also evaluated. The results confirmed that the confining stress affects the dynamic parameters. At higher stress levels, the signals aremore susceptible to the near field effects and the dynamic parameters are less influenced by cycling.

Peesey Swamp—a Last Interglacial (MIS 5e) marine corridor across southern Yorke Peninsula, southern Australia

Peesey Swamp on southern Yorke Peninsula, southern Australia, is a north-northwesterly—south-southeasterly trending lowland depression, approximately 24 km long and 4 to 10 km wide. The richly fossiliferous mollusc and foraminiferal faunal assemblages of the last interglacial Glanville Formation in Peesey Swamp indicate that the paleoenvironment was a low- to medium-energy, sheltered sandflat to shallow-water seaway during the Last Interglacial Maximum (Marine Isotope Substage [MIS] 5e; 128–116 ka). The presence of the fossil bivalve molluscs Katelysia rhytiphora, Chlamys (Equichlamys) bifrons and Fulvia tenuicostata, in life position, indicate that the paleowater depth was ≤4 m in Peesey Swamp. The seaway cut across southern Yorke Peninsula, establishing a marine connection between southern Spencer Gulf and Investigator Strait during deposition of these taxa. Amino acid racemisation dating of the fossil marine molluscs Katelysia sp. and Fulvia tenuicostata confirms that the shelly assemblages at Peesey Swamp are correlative with the last interglacial Glanville Formation, a succession of richly fossiliferous, mixed quartz–skeletal carbonate sands documented from many sites along the southern Australian coastline. This study illustrates the significant changes in the geographical configuration of coastlines that may accompany relatively modest (<5 m) sea-level changes on low-gradient coastal landscapes. KEY POINTS Peesey Swamp on southern Yorke Peninsula was flooded by seawater forming a 4 to 10 km-wide seaway during the Last Interglacial Maximum (MIS 5e). Fossil mollusc and foraminiferal assemblages reveal deposition within shallow subtidal to intertidal sandflat environments indicating that the paleowater depth and height of sea-level in Peesey Swamp was ≤4 m. Amino acid racemisation dating of fossil marine molluscs confirms that the shelly assemblages at Peesey Swamp are of last interglacial (MIS 5e) age. The distribution of the foraminifer Marginopora vertebralis indicates that the eastward flow of the warm-water Leeuwin Current, during the Last Interglacial Maximum, was retarded by the biogeographical barriers of Kangaroo Island and Fleurieu Peninsula.

Particle shape influence on the deformation resistance of carbonate sands under drained condition

The carbonate sand has high porosity and irregular particle shape compared with the quartz sand. Under dynamic loads, the carbonate sand perhaps experiences drained or partial drained shear, and the contribution of particle shape to its deformation resistance was still unrevealed. In this paper, particle shapes of five samples were first quantitively evaluated. Then, monotonic and cyclic tests under drained condition were carried out based on the simple shear apparatus. The particle size and shape were quantitively measured after the tests, and the particle breakage degree and its breakage mode were discussed. It is found that before phase transformation points (PT points), the irregular particles mobilize greater shear resistance. The particle breakage reduces the deformation resistance after the PT point due to its depression effect on the volume shear dilation. In cyclic shear, irregular particles have larger volume contraction due to the particle breakage, and the surface grinding is the major breakage mode. Under the same cyclic stress ratio (CSR), the irregular particles show smaller shear strain amplitudes, indicating that the irregular particles have stronger resistance to deformation. It is also found that the particle shape mainly influences the deformation resistance when the overall regularity (OR) is less than 0.8.

Effects of particle breakage on the compression behaviour of gap graded carbonate sand–silt mixtures

Isotropic compression tests were conducted on a series of gap-graded mixtures of a carbonate sand (CS) from the South China Sea and a fine crushed quartz silt. The purpose of these tests is to expl...

Spectral characteristics of coral reef benthic compositions in Gulf of Mannar

Spectral characteristics of nine coral species (Acropora Nobilis, Acropora Hyacinthus, Acropora Varibalis, Favia Speciosa, Favia Stelligera, Porites Lobdata, Porites sp., Pocillopora Domicornis and branched dead corals), two seagrass species (Zosteraceae and Posidoniaceae), two sand benthic communities (sand mixed with coral rubble and carbonate sand), reef vegetation and sea moss were recorded using RAMSES-TriOS Hyperspectral radiometer from Mandapam group of islands, Gulf of Mannar, India. Based on the reflectance features, coral reef benthic compositions were categorized as brown mode and blue mode. Brown mode of corals was identified by a triple peaked pattern exhibiting local maxima or shoulders near 575, 600 and 650 nm. The blue modes of corals were identified by a plateau-like shape between 600 and 650 nm. The non-coral benthic compositions such as seagrass and sea moss can be identified by a peak between 550 and 560 nm. Results exhibited that, most of the coral reef benthic compositions falling under either blue mode or brown mode of corals and the patterns of spectral signatures exhibited in this region are matching with existing global signatures.

Barium carbonate and supplementary cementitious materials to counteract thaumasite sulfate attack in mortars: Effect of aggregate composition

Abstract Supplementary cementitious materials (SCMs) have been shown to have a beneficial impact on carbonate-bearing mortar and concrete resistance to sulfates in general and thaumasite sulfate attack (TSA) in particular, although the effect is limited in some cases. In pursuit of improved sulfate-resistance formulations that inhibit thaumasite formation, this study added barium carbonate, both as mineral addition and as aggregate, to cements blended with SCMs. The aim was to immobilise sulfates via conversion to barite, a practically insoluble form of barium sulfate. The study was conducted on standardised mortars prepared with CEM I 52.5 N-SR 5 (reference, Ref) cement, laboratory-blended CEM III/C-SR (with slag) or CEM IV/B-SR (fly ash-bearing) cements. Mixes were also prepared with the latter two cements in which the slag or fly ash filler was partially replaced with barium carbonate. Barium or calcium carbonate sands were used as aggregate in the respective mortars, all of which were soaked in a Na2SO4 solution at 8 °C for 6 months and monitored for variations in mass, compressive strength, ultrasonic velocity, soundness (expansion) and mineralogy. The findings showed that at such low temperatures the amount of Ba2+ solubilised did not suffice to effectively immobilise the external sulfates in the blends containing SCMs. The fly ash-bearing samples, particularly where the addition was partially replaced with barium carbonate, deteriorated severely or very severely (substantial expansion and mass loss) because thaumasite precipitated even in the presence of the barite formed. The low cement content, slag-bearing blends exhibited greatest sulfate resistance, irrespective of the presence of barium carbonate as addition or aggregate. In mortars made with commercial, low C3A content (Ref.) sulfate-resistant cement, barium carbonate sand inhibited gypsum and ettringite formation, whereas both products precipitated in analogous and less porous mixes bearing limestone aggregate.

Penetration dynamics of a carbonate sand: A synchrotron phase contrast imaging study

Penetration into granular materials such as carbonate sand is of fundamental importance to granular physics, and impact and civil engineering, but research along this line suffers considerably from the lack of direct experimental observations. Here we investigate such penetration dynamics of carbonate sand using a vertical gas gun implemented with in situ, high-speed, synchrotron-based X-ray phase contrast imaging. The experiments yield the first direct observation on the penetration dynamics (projectile trajectory/velocity) and particle-scale deformation in real or natural granular materials during sphere penetration, at high temporal and spatial resolutions. The particle displacement fields around the projectile are obtained via X-ray digital image correlation, and the ejecta velocity fields, with particle image velocimetry. Effects of the moisture content and container size on the penetration process are discussed. The enhanced cohesion between wet particles results in particle clustering during splash and a smaller amount of ejecta. Therefore, the particle rearrangement is limited and the projectile penetration depth is smaller. A small container size confines the lateral movement of particles and yields a much more pronounced compaction of particles beneath the projectile, which results in a smaller penetration depth as well.

COMPARATIVE EXPERIMENTAL STUDY ON LIQUEFACTION CHARAC TERISTICS OF CARBONATE AND SILICA SANDS

Carbonate sand has the characteristics of irregular particle shape, high porosity and low particle strength, and thus exhibits more complicated liquefaction characteristics than silica sand. Physical property tests, undrained cyclic triaxial tests and light dynamic penetration tests are conducted to study the differences in physical properties, liquefaction resistance and penetration resistance between carbonate sand and silica sand. Carbonate sand is found to have larger void ratio and internal friction angle than silica sand, which is consistent with the characteristics of carbonate sand particles. The liquefaction resistance increases with increasing relative density for both sands, and it is found that under the same relative density, carbonate sand has higher liquefaction resistance than silica sand. The penetration resistance increases with increasing relative density for both sands, and it is also found that under the same relative density, carbonate sand has higher penetration resistance than silica sand. Combining the results of undrained cyclic triaxial tests and light dynamic penetration tests, it can be concluded preliminarily that the current liquefaction evaluation methods based on the empirical data on terrestrial silica sand foundations can be conservative for evaluating the liquefaction susceptibility of carbonate sand foundations.

Giant subaqueous carbonate dunes: a revised interpretation of large-scale oo-bioclastic clinoforms in the middle Jurassic of the Paris Basin and its implications

Recent developments of carbon capture and storage and geothermal subsurface prospects in the Middle Jurassic limestone of the central part of the Paris Basin have rejuvenated interest in the world class outcrops of the Bathonian Oolithe Blanche Formation on the southeastern edge of the Basin. Here, ooid-bioclast grainstones occur as large-scale (10–15 m high) clinoforms in the upper part of the Oolithe Blanche, which remain enigmatic and variously interpreted. High-resolution sequence stratigraphic correlations, constrained by biostratigraphic markers and integrated with regional palaeogeography, indicate that the clinoforms are giant dunes developed during the early part of the regressive phase of a third-order transgressive–regressive sequence (Bt3), in the northern part of the Burgundy Bathonian carbonate ramp. Carbonate sand bodies up to 15 m high with intervening troughs, formed subaqueous giant dune field(s) with calculated wavelengths of about 500–800 m. Using dune height as a proxy for calculating the palaeobathymetry of deposition, it is concluded that the dunes formed under a minimum water depth of about 60 m. A detailed facies analysis of the sediments underlying the dunes, which include beds rich in brachiopods in living position corresponding to the MFS of the third-order transgressive–regressive sequence (Bt3), supports such a water depth. The constitutive facies of the dunes themselves also reflect a significant water depth, despite the presence of ooids that are definitely transported away from their main production zone. This new interpretation of the large-scale clinoforms in the upper Oolithe Blanche and the associated revised palaeobathymetry have implications for the interpretations of Bathonian carbonates across the Paris Basin, which are relevant to ongoing projects of reservoir characterization of subsurface prospects.

Late Quaternary sea level, isostatic response, and sediment dispersal along the Queen Charlotte fault

Abstract The active Pacific margin of the Haida Gwaii and southeast Alaska has been subject to vigorous storm activity, dramatic sea-level change, and active tectonism since glacial times. Glaciation was minimal along the western shelf margin, except for large ice streams that formed glacial valleys to the shelf break between the major islands of southeast Alaska and Haida Gwaii. Upon deglaciation, sediment discharge was extensive, but it terminated quickly due to rapid glacial retreat and sea-level lowering with the development of a glacio-isostatic forebulge, coupled with eustatic lowering. Glacial sedimentation offshore ended soon after 15.0 ka. The shelf became emergent, with sea level lowering by, and possibly greater than, 175 m. The rapid transgression that followed began sometime before 12.7 ka off Haida Gwaii and 12.0 ka off southeast Alaska, and with the extreme wave-dominated environment, the unconsolidated sediment that was left on the shelf was effectively removed. Temperate carbonate sands make up the few sediment deposits presently found on the shelf. The Queen Charlotte fault, which lies just below the shelf break for most of its length, was extensively gullied during this short period of significant sediment discharge, when sediment was transported though the glacial valleys and across the narrow shelf through fluvial and submarine channels and was deposited offshore as sea level dropped. The Queen Charlotte fault became the western terminus of the glacio-isostatic forebulge, with the fault acting as a hinged flap taking up the uplift and collapse along the fault of 70+ m. This may have resulted in the development of the distinctive fault valley that presently acts as a very linear channel pathway for sediment throughout the fault system.