Hydraulic conductivity behavior of soilcrete specimens created from dredging sand, cement, and bentonite

2021 ◽  
Author(s):  
Hoang-Hung Tran-Nguyen ◽  
Bich Thi Luong ◽  
Phong Duy Nguyen ◽  
Khanh Duy Tuan Nguyen
Keyword(s):  
Hydraulic Conductivity ◽  
Mekong Delta ◽  
Research Data ◽  
Low Permeability ◽  
High Permeability ◽  
Seepage Flows ◽  
Southern Vietnam ◽  
Hydraulic Gradients ◽  
Conductivity Behavior

Abstract Dredging sand is an inexpensive material utilized to rise elevations of highway embankments and earth levee bodies in the Southern Vietnam. However, high permeability of the dredging sand can cause failures due to seepage flows during annual flood seasons. The dredging sand mixing cement with or without bentonite is expected to be suitable low permeability as an impermeable material. However, hydraulic conductivity of soilcrete and bentonite specimens created from dredging sand taken in the Mekong delta has limit research data. This study aims at better understanding the hydraulic conductivity of dredging sand samples taken in Dong Thap province mixed with cement and bentonite. The effects of the hydraulic conductivity of soilcrete and bentonite soilcrete specimens on time, cement contents, bentonite contents, cement types, and hydraulic gradients were investigated. The tests followed the ASTM D5084 standard using the both falling head-constant tailwater and falling head-rising tailwater methods. The results indicate that: (1) the hydraulic conductivity of the soilcrete and bentonite specimens decreased with increasing in testing duration and cement contents; (2) the hydraulic conductivity of the soilcrete specimens was lower 104 to 105 times than that of the compacted sand; (3) the hydraulic conductivity of the bentonite soilcrete specimens was lower 10 times than those of the soilcrete specimens; (5) the PCS cement can induce long-term reduction of soilcrete hydraulic; (6) effect of hydraulic gradients on soilcrete hydraulic conductivity was ignorable; (6) the soilcrete hydraulic conductivity varies from 10− 9 to 10− 10 m/s.

Prediction of Hydraulic Conductivity of Fly Ash Built-in Mineral Sealing Layers

2017 ◽  
Author(s):  
Mariola Wasil
Keyword(s):  
Fly Ash ◽  
Hydraulic Conductivity ◽  
Laboratory Tests ◽  
Physical Parameters ◽  
Low Permeability ◽  
Empirical Formulas ◽  
Semi Empirical ◽  
Sealing Layer ◽  
Compaction Method

Mineral barrier protects the groundwater and soil from contamination by insulating the leakage of harmful substances from landfill. One of the most important parameters, which decides about usefulness of material to built-in sealing layers, is hydraulic conductivity. Researchers have conducted investigations with the possibility of utilising fly ash as a mineral sealing layer material, which is justified by its low permeability and other properties. It is known that laboratory tests of hydraulic conductivity are often long-term and require expensive equipment. Therefore, to avoid this, researchers trying to assess permeability of tested material with empirical or semi empirical formulas. The aim of the paper is to compare the results of hydraulic conductivity of fly ash obtained from the laboratory tests and from estimation using different empirical formulas. Fly ash was compacted by the Standard Proctor compaction method at the optimum moisture content. The results obtained from empirical equations were variable. It was observed that the Kozeny-Carman formula and other, based on a few physical parameters of the soil, gave better results in prediction of hydraulic conductivity of fly ash than equations based on only one parameter.

High Temperature Ageing of Fe-based Nanocrystalline Ribbons

2012 ◽  
Vol 2012 (HITEC) ◽  
pp. 000260-000265 ◽  
Author(s):  
Christian Martin ◽  
Rémi Robutel ◽  
Cyril Buttay ◽  
Fabien Sixdenier ◽  
Pascal Bevilacqua ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Stress ◽  
Complex Permeability ◽  
Magnetic Flux Density ◽  
Low Permeability ◽  
High Permeability ◽  
Design Considerations ◽  
Temperature Ageing ◽  
The Impact

The impact of long-term high-temperature stress on nanocrystalline Finemet materials is measured by keeping samples at 200 °C for 1300 hours. The standard industrialized, high permeability Finemet materials as well as the recently available low permeability Finemet materials are investigated. Characterizations are performed at different frequencies, temperatures and magnetic field excitations on both aged and non-aged samples. Their complex permeability is also measured during the ageing test. Irreversible changes are pointed out on permeability, coercive field and magnetic flux density at saturation. Regarding the design considerations for high temperature power electronics, the suitability of these materials is demonstrated but an ageing effect has to be considered nonetheless. The presented data can be extrapolated to several thousand hours at 200 °C using the presented empiric ageing law.

scholarly journals Aquifer Response to Estuarine Stream Dynamics

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1678 ◽  
Author(s):  
Yehuda Shalem ◽  
Yoseph Yechieli ◽  
Barak Herut ◽  
Yishai Weinstein
Keyword(s):  
Eastern Mediterranean ◽  
Mediterranean Coast ◽  
Low Permeability ◽  
High Permeability ◽  
Dynamic Changes ◽  
Groundwater Levels ◽  
Groundwater Dynamics ◽  
Large Fluctuations ◽  
History Of

While seawater intrusions are widely discussed, the salinization of coastal aquifers via narrow rivers is hardly documented. This study investigates groundwater dynamics in an aquifer next to an estuarine stream on the eastern Mediterranean coast. Groundwater levels and salinization patterns were examined as a response to dynamic changes in estuary water, both in low-and high-permeability aquifer units. In the high-permeability unit, the extent of salinization was relatively constant, reaching a distance of at least 80 m from the river, with no long-term changes in fresh-saline interface depth, indicating that the system is in a quasi-steady state. Groundwater salinity in the low-permeability unit showed frequent and large fluctuations (up to 36 and 22 at 5 and 20 m from the river, respectively). We suggest that the river may have a more immediate impact on a low-permeability than on a high-permeability aquifer. This is dependent on the history of seawater encroachments to the river, which are better preserved in the low-permeability unit, and on the hydrogeology of this unit, where sand lenses can serve as high-permeability conduits. However, this unit can efficiently prevent a large extent of salinization of the regional coastal aquifer by the estuary water.

Subcritical Crack Growth and Long-Term Strength in Rock and High-Strength and Ultra Low-Permeability Concrete

2009 ◽  
Vol 58 (6) ◽  
pp. 525-532 ◽  
Author(s):  
Yoshitaka NARA ◽  
Masafumi TAKADA ◽  
Daisuke MORI ◽  
Hitoshi OWADA ◽  
Tetsuro YONEDA ◽  
...  
Keyword(s):  
Crack Growth ◽  
Subcritical Crack Growth ◽  
High Strength ◽  
Low Permeability ◽  
Term Strength

scholarly journals The on-premise data sharing infrastructure e!DAL: Foster FAIR data for faster data acquisition

GigaScience ◽  
2020 ◽  
Vol 9 (10) ◽  
Author(s):  
Daniel Arend ◽  
Patrick König ◽  
Astrid Junker ◽  
Uwe Scholz ◽  
Matthias Lange
Keyword(s):  
Data Management ◽  
Data Storage ◽  
Best Practice ◽  
Research Process ◽  
Research Data ◽  
Primary Data ◽  
Data Repository ◽  
Plant Genomics ◽  
Quality Of Data

Abstract Background The FAIR data principle as a commitment to support long-term research data management is widely accepted in the scientific community. Although the ELIXIR Core Data Resources and other established infrastructures provide comprehensive and long-term stable services and platforms for FAIR data management, a large quantity of research data is still hidden or at risk of getting lost. Currently, high-throughput plant genomics and phenomics technologies are producing research data in abundance, the storage of which is not covered by established core databases. This concerns the data volume, e.g., time series of images or high-resolution hyper-spectral data; the quality of data formatting and annotation, e.g., with regard to structure and annotation specifications of core databases; uncovered data domains; or organizational constraints prohibiting primary data storage outside institional boundaries. Results To share these potentially dark data in a FAIR way and master these challenges the ELIXIR Germany/de.NBI service Plant Genomic and Phenomics Research Data Repository (PGP) implements a “bring the infrastructure to the data” approach, which allows research data to be kept in place and wrapped in a FAIR-aware software infrastructure. This article presents new features of the e!DAL infrastructure software and the PGP repository as a best practice on how to easily set up FAIR-compliant and intuitive research data services. Furthermore, the integration of the ELIXIR Authentication and Authorization Infrastructure (AAI) and data discovery services are introduced as means to lower technical barriers and to increase the visibility of research data. Conclusion The e!DAL software matured to a powerful and FAIR-compliant infrastructure, while keeping the focus on flexible setup and integration into existing infrastructures and into the daily research process.

scholarly journals Assessing Stream-Aquifer Connectivity in a Coastal California Watershed

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 416
Author(s):  
Bwalya Malama ◽  
Devin Pritchard-Peterson ◽  
John J. Jasbinsek ◽  
Christopher Surfleet
Keyword(s):  
Time Series ◽  
Spectral Analysis ◽  
Water Level ◽  
Time Series Data ◽  
Series Data ◽  
Low Permeability ◽  
Pumping Tests ◽  
Stream Flows ◽  
The Impact

We report the results of field and laboratory investigations of stream-aquifer interactions in a watershed along the California coast to assess the impact of groundwater pumping for irrigation on stream flows. The methods used include subsurface sediment sampling using direct-push drilling, laboratory permeability and particle size analyses of sediment, piezometer installation and instrumentation, stream discharge and stage monitoring, pumping tests for aquifer characterization, resistivity surveys, and long-term passive monitoring of stream stage and groundwater levels. Spectral analysis of long-term water level data was used to assess correlation between stream and groundwater level time series data. The investigations revealed the presence of a thin low permeability silt-clay aquitard unit between the main aquifer and the stream. This suggested a three layer conceptual model of the subsurface comprising unconfined and confined aquifers separated by an aquitard layer. This was broadly confirmed by resistivity surveys and pumping tests, the latter of which indicated the occurrence of leakage across the aquitard. The aquitard was determined to be 2–3 orders of magnitude less permeable than the aquifer, which is indicative of weak stream-aquifer connectivity and was confirmed by spectral analysis of stream-aquifer water level time series. The results illustrate the importance of site-specific investigations and suggest that even in systems where the stream is not in direct hydraulic contact with the producing aquifer, long-term stream depletion can occur due to leakage across low permeability units. This has implications for management of stream flows, groundwater abstraction, and water resources management during prolonged periods of drought.

scholarly journals Mapping Groundwater Seepage in a Fen Using Thermal Imaging

Geosciences ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 29
Author(s):  
Ogochukwu Ozotta ◽  
Philip J. Gerla
Keyword(s):  
Hydraulic Conductivity ◽  
Thermal Imaging ◽  
Crucial Role ◽  
Groundwater Discharge ◽  
Late Summer ◽  
Groundwater Temperature ◽  
Groundwater Seepage ◽  
Heterogeneous Soil ◽  
Hydraulic Gradients ◽  
Warm Soil

The transport of dissolved minerals and groundwater flow plays a crucial role in the ecosystem of many wetlands. Nonetheless, installing equipment to monitor groundwater seepage is invasive, harms vegetation, and can impact biodiversity. By remotely mapping surface temperature in late summer, when there is the greatest difference between warm soil and cold groundwater, temperature patterns can expose areas with the greatest upward gradient and flow. The conventional method of using tensiometers to measure hydraulic gradient and estimate flux using Darcy’s law was applied and compared with thermal imaging to characterize groundwater seepage at two contrasting sites within a central North Dakota fen (groundwater discharge wetland). Both sites exhibited variable gradients between the shallow and deep tensiometers. The temperature trend determined from the thermal imaging showed a closer relationship to the measured hydraulic gradients at the herbaceous (Sedge) site than at the wooded (Willow) site. Saturated hydraulic conductivity K ranged from 6 × 10−5 to 2 × 10−4 m/s for the Willow site; and 6 × 10−6 to 1 × 10−4 m/s for Sedge site. The flux calculated for the Willow site ranged from 1.4 × 10−5 to 2.7 × 10−4 m/s and that of the Sedge site ranged from 2.2 × 10−6 to 6.3 × 10−5 m/s. The gradients are affected at shallow depth because of heterogeneous soil stratigraphy, which is likely the reason that seepage faces at the sites cannot be mapped solely by thermal imaging.

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