On the influence of ionic strength on the rheological properties of kaolin
Typ
Examensarbete för masterexamen
Program
Infrastructure and environmental engineering (MPIEE), MSc
Publicerad
2019
Författare
Serrano Romero, Julio Cesar
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
This Thesis presents an experimental study that investigates the effect water content
and pore water chemistry on the emerging hydro-mechanical response of clay
samples. In order to capture the basic strength and stiffness response as function
of strain amplitude and rate, rheology experiments have been performed. As opposed
to standard geotechnical tests rheology experiments are fast to execute, more
consistent and only require small sample volumes. In order to properly benchmark
the rheometer apparatus for testing soft soils kaolin was used. The latter reduces
the complexity associated with natural materials at the expense of some saillant
features (such as the high sensitivity in sensitive clays) and allows to control the
initial conditions to the required degree. The samples consisted of kaolin slurries
prepared at differnt void ratios and with different initial pore water salinities, one
slurry with a water content equal to the liquid limit and another slurry with 1.5
times the liquid limit. Furthermore, a reconstituted sample was consolidated to 80
kPa. Two series of slurries were prepared, i.e. a reference slurry with distilled water
and saline slurry where 0.2 M NaCl was added to the pore water. The results showed
that the effect of NaCl is most pronounced for the slurries with water content equal
to the liquid limit and 150% the liquid limit. In contrast the effect of NaCl in the
reconstituted consolidated sample was less evident. Finally, a different series was
performed that emulated leaching of the saline pore water composition to simulate
some of the processes that occur during the formation of sensitive clay deposits.
These initial tests show that the beneficial effects of a saline injection can be fully
reversed by subsequent leaching with fresh water.
Beskrivning
Ämne/nyckelord
kaolinite , reconstituted sample , slurry , ionic influence , NaCl , viscosity , leaching , quick clay , double layer , pH