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Characterization of Dispersive Soils
The concept of dispersive soils is particularly significant with reference to earthen dams, embankment, canals, etc. The comparatively less explored role of surface chemistry in understanding dispersive phenomenon leads to a state of doubt and confusions among various researchers. Dispersive soils are those with unique properties which under certain conditions deflocculates and are rapidly eroded and carried away by water flow. These soils are highly prone to erosion often leading to tunnel and gully erosion. Dispersive clays have an imbalance in the electrochemical forces between particles. This imbalance causes the minute soil particles in a dispersive clay to be repulsed rather than attracted to one another. Using dispersive clay soils in hydraulic structures, embankment dams, or other structures such as roadway embankments can cause serious engineering problems if these soils are not identified and used appropriately. The tendency for dispersive erosion in a given soil depends on variables such as mineralogy and chemistry of the clay, as well as dissolved salts in the water in soil pores and in the eroding water. The presence of exchangeable sodium is a main contributing chemical factor to dispersive clay behavior. The laboratory tests generally performed to identify dispersive clays are the crumb test, double hydrometer test, pinhole test, test of dissolved salts in the pore water, and the sodium absorption ratio (SAR). The extracted soil pore water is tested using routine chemical tests to determine the amounts of the main dissolved cations; calcium, magnesium, sodium, and potassium, in terms of milliequivalents per liter (mEq/L). The percent sodium and TDS (sum of the four metallic cations) are determined. This article discussed the characterization and identification of dispersive soils based on chemical methods. The mineralogical characterization of soils were also studied using X-ray diffraction (XRD). The soil samples from different projects were compared for dispersive behavior based on slandered tests. The results show that soils with higher concentration of exchangeable sodium and presence of typical clay mineralogy are responsible for dispersive behavior.
Characterization of Dispersive Soils
The concept of dispersive soils is particularly significant with reference to earthen dams, embankment, canals, etc. The comparatively less explored role of surface chemistry in understanding dispersive phenomenon leads to a state of doubt and confusions among various researchers. Dispersive soils are those with unique properties which under certain conditions deflocculates and are rapidly eroded and carried away by water flow. These soils are highly prone to erosion often leading to tunnel and gully erosion. Dispersive clays have an imbalance in the electrochemical forces between particles. This imbalance causes the minute soil particles in a dispersive clay to be repulsed rather than attracted to one another. Using dispersive clay soils in hydraulic structures, embankment dams, or other structures such as roadway embankments can cause serious engineering problems if these soils are not identified and used appropriately. The tendency for dispersive erosion in a given soil depends on variables such as mineralogy and chemistry of the clay, as well as dissolved salts in the water in soil pores and in the eroding water. The presence of exchangeable sodium is a main contributing chemical factor to dispersive clay behavior. The laboratory tests generally performed to identify dispersive clays are the crumb test, double hydrometer test, pinhole test, test of dissolved salts in the pore water, and the sodium absorption ratio (SAR). The extracted soil pore water is tested using routine chemical tests to determine the amounts of the main dissolved cations; calcium, magnesium, sodium, and potassium, in terms of milliequivalents per liter (mEq/L). The percent sodium and TDS (sum of the four metallic cations) are determined. This article discussed the characterization and identification of dispersive soils based on chemical methods. The mineralogical characterization of soils were also studied using X-ray diffraction (XRD). The soil samples from different projects were compared for dispersive behavior based on slandered tests. The results show that soils with higher concentration of exchangeable sodium and presence of typical clay mineralogy are responsible for dispersive behavior.
Characterization of Dispersive Soils
Lecture Notes in Civil Engineering
Satyanarayana Reddy, C. N. V. (editor) / Muthukkumaran, K. (editor) / Satyam, Neelima (editor) / Vaidya, Ravikiran (editor) / Vyas, Sameer (author) / Anand, Beena (author) / Kumar, Rajeev (author) / Gupta, S. L. (author)
2021-09-27
8 pages
Article/Chapter (Book)
Electronic Resource
English
Characterization of Dispersive Soils
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