Saline Sand Research Articles

Frozen Saline Sand Can Be Highly Permeable

AbstractMass transport in frozen ground is typically regarded slow. However, a highly permeable path can exist in frozen saline sand if the unfrozen water is interconnected at the pore scale. We therefore should consider when the unfrozen water is connected and how permeable can frozen saline sand be, yet there are few studies. This research utilizes in‐situ X‐ray CT to evaluate unfrozen water connectivity and permeability in frozen saline sand considering effects of initial salt content, temperature, freezing rate, and temperature gradient. Results show that higher initial salt content and/or temperature, both of which results in a higher unfrozen water content, easily maintains unfrozen water connectivity. Rapid freezing minimizes the brine expulsion and permits a higher unfrozen water content hence better connectivity. Permeability in frozen saline sand can be several orders higher than the typically reported value, highlighting the potential presence of rapid mass transport through the connected unfrozen water.

Study on Strength Characteristics of Sodium Sulfate Saline Sand Based on Homogenization Theory

Study on Strength Characteristics of Sodium Sulfate Saline Sand Based on Homogenization Theory

Silicon-Mediated Improvement in Drought and Salinity Stress Tolerance of Black Gram (Vigna mungo L.) by Modulating Growth, Physiological, Biochemical, and Root Attributes.

Water is a precious commodity for plant growth and metabolism; however, its scarcity and saline sand conditions have a drastic effect on plant growth and development. The main objective of the current study was to understand how silicon (Si) application might help Black gram (Vigna mungo L.) against the negative impacts of salt stress and drought. The treatments of this study were: no silicon = 0 mg/kg; silicon = 40 mg/kg; control = no stress; drought stress = 50% field capacity (FC); salinity = 10 dSm-1; drought + salinity = 10 dSm-1 + 50% field capacity (FC). The findings showed that the application of silicon in the sand significantly affected growth indices such as leaf area (LA), shoot fresh weight (SFW), shoot dry weight (SDW), and shoot length (SL). Root length (RL) increased significantly up to 55.9% in response to drought stress. Applying Si to the sand increased the root length (RL) by 53.9%. In comparison to the control, the turgor potential of leaves decreased by 10.3% under salinity, while it increased by 44.7% under drought stress. However, the application of silicon to the sand significantly improved the turgor potential of leaves by 98.7%. Under both drought and salt stress, gas exchange characteristics and photosynthetic pigments dramatically decreased. Applying 40 mg/kg silicon to sand improved the gas exchange characteristics, protein contents, and photosynthetic pigments of plants under drought and salt stress, such as levels of chlorophyll (a, and b) increased by 18% and 26%, respectively. Under control conditions, the hydrogen peroxide (H2O2) concentration was lower but increased during periods of drought and salinity stress. The concentrations of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) were decreased by salt and drought stress and increased by sand application of silicon at a rate of 40 mg/kg. Application of silicon at 40 mg/kg sand rate improved the growth and development under control and stress conditions. Overall, this study provides an extensive understanding of the physiological mechanisms underlying the black gram's ability to withstand under salt stress and drought stress by application of Si which will serve as a roadmap for future cellular research.

Survey, classification and organization of use salt-contaminated sand as aggregates for reinforced concrete

The survey results of some types of saline-contaminated sand show that the mechanical and physical properties of this sand are similar to that of yellow sand, but most of the surveyed salt-contaminated sand samples have a higher chloride content than the allowable level, so when using For reinforced concrete structures, measures must be taken to protect against corrosion from the beginning. In this paper, on the basis of testing the physical and chemical properties of 19 types of saline-contaminated sands in Vietnam's sea, initially synthesized and classified the basic properties of sand according to chloride content, proposing requirements Corrosion protection for reinforcement in concrete using saline-contaminated sand aggregates based on research results on using saline sand as aggregate for reinforced concrete structures used in civil works, suitable for environmental zoning Vietnamese marine.

Influence of brine leakage on frozen wall development in offshore sand layer when active freezing: A numerical study

Brine leakage after freezing pipe fracture when active freezing will cause local structural defects or even failure of frozen wall. A water-heat-solute coupled model that includes a modified Michalowski model considering both temperature and salt concentration was proposed to simulate the freezing construction in offshore sand layer. It was verified by the artificial freezing model tests of saturated saline sand under seepage. The structural defects of frozen wall were observed at the boundary between straight and arch walls on the upstream. The range of the structural defect and the closing time of frozen wall both rise with larger pressure head. The brine leakage was then simulated to evaluate the effects of both pressure head and fracture range of freezing pipe on the structural defect of frozen wall. As indicated by the normalized unfrozen water content contour, there are obvious flaws in determining whether the frozen wall is closed only by the average temperature when brine leakage. A characteristic index, the area ratio of structural defect of frozen wall, was derived from the normalized unfrozen water content contour. The structural defect results from brine leakage when the pressure head is below 2.0 m, otherwise from both brine leakage and groundwater seepage. It is recommended that in addition to monitoring temperature during active freezing, additional moisture monitoring devices should be installed to prevent brine leakage hazards.

Assessment of the Efficiency Restriction of Amine based Inhibitor for Constructional Steel in a Saline Sand Concrete

Assessment of the Efficiency Restriction of Amine based Inhibitor for Constructional Steel in a Saline Sand Concrete

Strength of partially frozen sand under triaxial compression

To investigate the effect of the pore matrix (i.e., ice and unfrozen water) on the strength of partially frozen sand, a series of triaxial compression tests with internal pore water pressure (PWP) measurements were performed. Both dense and loose saline sand samples were prepared by rapidly freezing the samples and then slowly warming the samples to, and subsequently shearing at the temperature of −3 °C. Test results indicate the temperature only affects the effective cohesion, not the effective friction angle of sand. The pore ice stress was estimated using Ladanyi and Morel’s 1990 postulate on the internal stresses within frozen soil; the stress (hydrostatic) change in pore ice was reflected by an equal change in PWP in the partially frozen loose sand. Based on Ladanyi and Morel’s 1990 concept of internal confinement in frozen sand, a Mohr–Coulomb model that uses effective failure and residual friction angles from unfrozen sand to estimate the strength of partially frozen sand is presented. The proposed model reflects how the pore matrix contributes to the strength of partially frozen sand. For loose sand, the peak strength is enhanced by the internal confinement and cohesion resulting from the pore water (suction) and pore ice, respectively. For dense sand, only pore ice affects the peak strength by incorporating the internal confinement and cohesion.

EXPERIMENTAL STUDY ON BEHAVIOR OF SALT-CONTAMINATED SAND CONCRETE BEAM WITH EPOXY COATED REINFORCEMENT

This paper presents the results of comparing the instantaneous working performance in the period before the plastic reinforcement, of the saline aggregate reinforced concrete beams and the clean sand aggregate reinforced concrete beams. The authors performed theoretical and experimental calculations on the bearing capacity of three pairs of beams (salinated sand beams – clean sand beams) corresponding to concrete with strength levels B20, B30 and B45. Concrete with salt-contaminated sand aggregates using corrosion inhibitors and reinforced steel is coated with epoxy coating with thickness 175±18µm. Saline sand aggregates Thuan An - Hue, Tra Khuc - Quang Ngai and Bai Dai - Van Don (Quang Ninh), clean sand aggregates are Song Lo yellow sand. Concrete beams are calculated according to TCVN 5574-2018 standard and tested according to TCVN 9347-2012.

Evaluation of the freezing point of offshore saline sand based on the extended UNIQUAC model

Evaluation of the freezing point of offshore saline sand based on the extended UNIQUAC model

STUDY ON SOME DURABILITY PROPERTIES OF HIGH-STRENGTH FINE-GRAINED CONCRETE USING SALINE SAND AND CRUSHED AGGREGATE

This paper presents the results of research on some durability properties of high-strength fine-grained concrete made from saline sand and crushed aggregates with different mixing ratios. The specific mechanical properties and durability of concrete when working in a saline environment were tested, including compressive strength, water absorption, sulfate durability, and the alkali-aggregate reaction of concrete. The results show that: when replacing regular aggregate in C50 concrete with a mixture of salted sand and crushed aggregate with an appropriate mixing ratio, the concrete has a compressive strength of over 50 MPa, and water absorption reduces significantly. The sulfate and alkali-aggregate reaction are guaranteed to meet the requirements set forth by the standards for sulfate and alkali-resistant durability concrete. This result has great significance in the study and application of high-strength fine-grained concrete made from saline sand to build the constructions in marine and island environments.

Experimental Study on Temporal and Spatial Evolutions of Temperature Field of Double-Pipe Freezing in Saline Stratum with a High Velocity

Freezing construction in saline stratum under the action of groundwater is typical. To study the coupling effect of the groundwater velocity and salinity on the freezing in saline stratum, the freezing temperature of saline sand with different salinities was obtained through experiments. A controllable velocity double-pipe freezing physical model test system for saline sand was established. The temperature distribution in saturated saline sand under different salinities and velocities were studied. The test results showed that the temporal and spatial evolutions of the temperature field were affected by the velocity and salinity. Under the same boundary temperature, the higher the salinity, the lower the temperature at the measuring point on the main surface and interface. The overlapping time varies significantly. The analysis results showed that the larger velocity and the higher the salinity, the longer the overlapping time. The velocity and salinity inhibited the development of the frozen curtain. Under different test conditions, the development rate of the freezing curtain area was in the range of 3987–15,246 mm2/h.

Equilibrium Conditions of the Natural Gas Hydrates Formation in the Pore Space of Dispersed Rocks

In this work, the kinetic parameters and equilibrium conditions of the formation of natural gas hydrates in moist fresh and saline sand samples were studied by the method of differential thermal analysis. It was found that, in comparison with the systems "water-natural gas" and "sodium chloride solution-natural gas" in dispersed rocks, the equilibrium curves of hydrate formation are shifted to the region of high pressures and low temperatures. It is shown that the salinity of the pore solution leads to a decrease in the amount of absorbed gas and a decrease in the rate of hydrate formation.

Electrical Conductivity‐Based Estimation of Unfrozen Water Content in Saturated Saline Frozen Sand

The salinity of the pore solution is closely associated with the unfrozen water content and can be reflected by variation in electrical conductivity in frozen soils. However, the influence of salinity was not considered in the existing models for estimation of unfrozen water content based on electrical conductivity measurement, and a model considering the effect of salt content was therefore developed to estimate the change of unfrozen water content of saline sands with variation of salt content (0%, 0.2%, and 1%). The unfrozen water content and the electrical resistivity were measured by nuclear magnetic resonance (NRM) and using resistance test equipment under a temperature ranging from 25°C to −15°C, respectively. The results indicated that the model using a cementation exponent expressed by a piecewise function with respect to temperature can produce a reasonable estimation on the content of unfrozen water. There was an essential difference between nonsaline and saline frozen sands in the increase of electrical resistivity due to the different reduction rates of unfrozen water content. The variation of electrical resistivity in nonsaline sand was mainly caused by the decrease of free water when temperature was higher than the freezing point and adsorbed water when temperature was lower than the freezing point, whereas the reduction of free water in two stages was the main reason for the variation of electrical resistivity in saline sand. The results and data obtained provided a basis for further developing a novel approach to measure the unfrozen water content in the field.

Response of nodulation, nitrogen fixation to salt stress in a desert legume Alhagi sparsifolia

Salinity has adverse effects on the nitrogen (N) metabolism of legumes in dryland ecosystems. Although the response of biological N fixation (BNF) to salt stress has received much research attention, less is known about how N fixing plants may adjust their N acquisition strategies in response to variation in salt stress. Alhagi sparsifolia, a perennial deep-rooted legume located in both riparian and desert environments of the hyperarid Taklimakan Desert, China, is a regionally important species due to its capacity for fixing atmospheric N and increasing soil stability. We investigated how groundwater biogeochemistry was related to seasonal differences in BNF of Alhagi sparsifolia located at terminal ends of a soil salinity gradient (high salinity riparian; inland low salinity sand dunes) in the Taklimakan Desert. Additionally, to elucidate the plasticity of A. sparsifolia nitrogen fixation to variation in soil salinity, we experimentally treated Alhagi seedlings from the same parental lineage with NaCl, Na2SO4, NH4NO3, and groundwater, and evaluated N fixation potential via root nodule development. We did not find evidence that mineral nitrogen concentrations influenced the varied N2 fixation rates (indicated by foliar δ15N value) in A. sparsifolia that we observed in the field. Instead, BNF of Alhagi plants was higher in high salinity riparian areas, whereas these plants utilized groundwater N when located in low salinity inland sand dunes. In our experimental treatments, salt addition did not significantly influence the nodulation of Alhagi seedlings, suggesting that nitrate assimilation instead of BNF is suppressed by salt stress. Thus, BNF in A. sparsifolia is tolerant to salt stress, and can be adjusted in response to variation in N availability and soil salinity. Relationships between salt tolerance and biological nitrogen fixation in A. sparsifolia explains how these species can increase soil nutrient availability across differing dryland environments, and illustrates a possible strategy whereby dryland legumes enhance their adaptability to saline environments by both building symbiotic associations with Rhizobium and utilizing readily available N when salt stress is less prohibitive.

The effects of projects of dredging and recovering saline sand at estuaries in Binh Thuan - Ninh Thuan provinces

According to statistics in Binh Thuan - Ninh Thuan provinces, there are 4 projects of dredging and recovering saline sand at estuaries such as La Gi, Ca Ty, Phan Ri Cua and Dong Hai. These projects use dredging plans by sand suction vessel and scraper bucket to scoop sand on barges, then sand is transferred to ships for exportation or used for levelling platform of urban buildings on the south bank of estuaries. The channel dredging process has changed and distributed the energy of waves, currents, tides, dynamics, incident wave fields, geological structures, topographic characteristics of the shore and bottom, thereby forming the new erosion - deposition process, affecting the shoreline in estuaries.

Effect of Sea Water on Strength of Concrete Made By River Sand and Sea Sand

Constructions across seashore increasing day by day (likely road pavements, bridges, hotels etc.,) But these are facing so many challenges by less availability chances of normal sand, water and huge amount of availability of saline sand, water. Sea water has 35ppt of an average salinity but in some places around shoreline salinity of ground water may vary from 0 to 35ppt due to humidity and temperature of ground surface. It will effect on durability of constructions at shore. In this investigation, the effect of saline content on M40 grade concrete(for road pavements)made by river sand and sea sand with partial and complete replacement of sea water specimen strength was studied. Total 216 specimens were casted using PPC cement in that 108 were casted using river sand and 108 were casted using sea sand with partial and complete replacement of sea water to test 7,14,28 days compressive & split-tensile strength of concrete specimens. Compressive strength test was conducted on cubes and Split-tensile strength was conducted on cylinders. PPC (fly ash based) cement is preferable for marine constructions due to its low heat of hydration and it has good resistance against saline attack. Sea water replaced as by 20%, 40%, 60%, 80% and 100% with normal water for different salinity ranges of water. Salinity was tested by Salinity Refractometer. River sand was collected from Vamsadhara River near srikakulam and sea water and sand was collected from kalingapatnam near srikakulam.

Influence of salinity and moisture on the threshold shear velocity of saline sand in the Qarhan Desert, Qaidam Basin of China: A wind tunnel experiment

Determination of the threshold shear velocity is essential for predicting sand transport, dust release and desertification. In this study, a wind tunnel experiment was conducted to evaluate the influence of salinity and moisture on the threshold shear velocity of saline sand. Saline sand samples (mean particle size of 164.50–186.08 µm and the total silt, clay and salt content of 0.80%–8.25%) were collected from three saline sand dunes (one barchan dune and two linear dunes) in the Qarhan Desert, Qaidam Basin of China. Original saline sand samples were placed in two experimental trays for wet and dry processing to simulate deliquescence and desiccation, respectively. Surface moisture content ranging from 0.30% to 1.90% was generated by the steam method so that the saline sand can absorb water in a saturated water vapor environment. The motion of sand particles was determined by the observers with a solid laser. The laser sheet (0.80 cm thick), which was emitted by the solid laser, horizontally covered the sand surface and was bound to the sand. Results show that the cohesion of saline sand results from a combination of salt and water. The threshold shear velocity increases exponentially with the increase in crust thickness for the linear sand dunes. There is a positive linear correlation between the original moisture content and relative threshold shear velocity. The threshold shear velocity of dewatered sand is greater than that of wet sand with the same original moisture content. Our results will provide valuable information about the sand transport of highly saline soil in the desert.

Static and cyclic shear behaviour of saline dredged sand

ABSTRACT Large amounts of dredged sand accumulate along the banks of the Suez Canal in Egypt, which can be used in engineering applications subject to monotonic and cyclic loading. This research studied static and cyclic shear behaviour of reconstituted saline dredged sand. Constant volume direct simple shear tests were conducted to evaluate the effects of salt content (SC), relative density (Dr ), cyclic stress ratio (CSR), and normal effective stress (σvc’) on static and cyclic resistances of saline sand. Tests were conducted on specimens prepared at Dr of 40 and 80% with SC ranging from 0.25% to 20%. Specimens were consolidated at different σvc’, then sheared statically or cyclically at different CSR values. The results of conducted tests showed that the angle of shearing resistance decreased as SC increased beyond 4%. Failure under cyclic loading was governed by liquefaction rather than cyclic mobility. The cyclic resistance increased as SC increased beyond 9%.

Field assessment of potential pistachio salt toxicity using the EM38

The traditional concept of crop salt tolerance as a single soil saturation extract salinity threshold with a “% relative yield decline” function is over-simplified. This approach minimizes the real world variability in actual tree growth and yield due to the added effects of specific ion toxicity and soil texture and anoxia from soil saturation. The current salinity tolerance function for California pistachios was developed from a small plot study in an 8th-13th leaf orchard in northwestern Kern County from 1997-2002. Results from this trial and seedling growth studies in saline sand tanks at the USDA Salinity Lab indicated a threshold value of 9.4 dS m-1 ECe with an 8.4% decline above that value. A greatly expanded salinity survey across 520 km2 examining 10 commercial fields (540 ha total, 9th-15th leaf, centered 35.463 Lat., -119.500 Long.) in western Kern County with 140 individual tree data points was conducted from 2014-16. Average root zone (1.5 m depth) salinity was 1.6 to 20.5 dS m-1. A statistically significant yield reduction of 162-394 kg ha-1 (1-3%) was found in 3 year cumulative inshell yield for every unit ECe>6.5 dS m-1. However, the R2 was only 0.11. Yield by the Ln transformed EM38-ECa was R2=0.20. However, the best predictor of yield decline was the ln transforms of inshell yield and the simple sum of the uncalibrated vertical + horizontal raw EM readings adjacent to the tree, R2=0.35. The raw electromagnetic resonance readings from the EM38 will incorporate multiple factors such as possible anoxia due to high water content and poor soil structure with some influence of the soil mineralogy and pH along with total salt (EC).

Delineation of Groundwater Potential and Recharge Zone Using Electrical Resistivity Method Around Veeranam Tank, Tamil Nadu, India

Veeranam tank is one of the largest tank in Tamil Nadu, India which plays a vital role in groundwater recharge to the surrounding aquifer. Electrical resistivity survey were carried out in ten locations around the Veeranam tank. The resistivity, thickness of subsurface formations, longitudinal conductance (S), transverse resistance (R), average longitudinal resistivity (ST), average transverse resistivity (RT) and anisotropy (λ) were used to characterize the lithological formations and also groundwater potential and recharge zones were delineated. The four major zones clay, clayey sand, saline sand and sandstone were identified as a result of primary geo-electrical parameters which includes resistivity and thickness of the formations. The sandstone formation is identified as good water bearing formation and this formation possess low longitudinal conductance, high transverse resistance, and low anisotropy values. The clay and saline formation possess high longitudinal conductance, low transverse resistance and high anisotropy values and these formations are identified as moderate groundwater water bearing formations. High longitudinal conductance is observed in eastern region of the study area due to intrusion of saline water. Sandstone formation of low longitudinal conductance is associated with high percolation rate and groundwater potential is also good in this formation. High transverse resistance zones are associated with high infiltration rate and high transmissivity whereas groundwater potential is good in these zones. VES 2 and VES 3 stations comprises of sandstone formation as second layer and Veeranam tank water infiltrated into these zones due to high infiltration rate of these formations. The resistivity value is decreased in VES 10 station due to intrusion of sea water. The true resistivity near the Veeranam tank is high and decreases towards east which clearly indicates that groundwater recharge is the major process that occurs nearby the downstream shore of tank and intrusion of saline water in the eastern part of the study area. Thus good interaction between exists between Veeranam tank and its downstream zones and interaction decreases as the distance increases from the tank.