Group 8 Dispersive Soils
Tshwane University of Technology
Department of Environmental Sciences
Engineering Geology
Group 8 Assignment:
Dispersive Soils
Group Members:
1. Elsie Phelane
2. Keeme Sephikwe
3. Lawrance Mabasa
4. Lethlogonolo kotsedi
DISPERSIVE SOILS
INTRODUCTION
Dispersive soils are associated with residual granites, granodiorites, mudstone and sandstone as well as fine-grained transported soils such as alluvium deposits. Dispersitivity is found in clay, silty and sandy soil. Dispersible soils tend to be highly erodible and present problems for successfully managing earth works.
It is an indicator of sodic soils as it occurs when excessive sodium is present, when water is added the sodium attach to the clay and forces the clay particles apart. This results in a cloud of clay forming around the aggregate.
The fine clay particles that have dispersed clog up the small pores in the soil and degrade the soil structures as well as restricting root growth and water movement.
DEFINITION
Dispersible soils are soils that are structurally unstable and disperse in water into basic particles (sand, silt and clay).
DESCRIPTION OF DESPERSIVE CLAY SOILS
Initially, clay soils were thought to be highly resistant to erosion from the flow water, lately it has been found that highly erodible clay soils exist in nature. Some natural clay soils disperse in the presence of relatively pure water and are highly susceptible to erosion. 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 (Sherard and Decker, 1977).
These clays are eroded faster by slow-moving water, even when compared to cohesion-less fine sands and silts. When dispersive clay soil is immersed in water, the clay fraction behaves like single-grained particles, the clay particles have a minimum of electrochemical attraction and fail to closely bond with other soil particles.
Department of Environmental Sciences
Engineering Geology
Group 8 Assignment:
Dispersive Soils
Group Members:
1. Elsie Phelane
2. Keeme Sephikwe
3. Lawrance Mabasa
4. Lethlogonolo kotsedi
DISPERSIVE SOILS
INTRODUCTION
Dispersive soils are associated with residual granites, granodiorites, mudstone and sandstone as well as fine-grained transported soils such as alluvium deposits. Dispersitivity is found in clay, silty and sandy soil. Dispersible soils tend to be highly erodible and present problems for successfully managing earth works.
It is an indicator of sodic soils as it occurs when excessive sodium is present, when water is added the sodium attach to the clay and forces the clay particles apart. This results in a cloud of clay forming around the aggregate.
The fine clay particles that have dispersed clog up the small pores in the soil and degrade the soil structures as well as restricting root growth and water movement.
DEFINITION
Dispersible soils are soils that are structurally unstable and disperse in water into basic particles (sand, silt and clay).
DESCRIPTION OF DESPERSIVE CLAY SOILS
Initially, clay soils were thought to be highly resistant to erosion from the flow water, lately it has been found that highly erodible clay soils exist in nature. Some natural clay soils disperse in the presence of relatively pure water and are highly susceptible to erosion. 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 (Sherard and Decker, 1977).
These clays are eroded faster by slow-moving water, even when compared to cohesion-less fine sands and silts. When dispersive clay soil is immersed in water, the clay fraction behaves like single-grained particles, the clay particles have a minimum of electrochemical attraction and fail to closely bond with other soil particles.