| dc.description.abstract | Soil is a very important element in a construction which acts as a supporting
foundation for all types of construction or construction materials. One of the
problems that often occurs in soil is soft soil, one of which is clay. Clay soil is a
type of soil with low bearing capacity and shear strength conditions, chemical soil
improvement stability is required. Parameters that can be known whether the
bearing capacity of the soil is good or not can be seen from the CBR value and the
shear strength value.
In this study, gypsum powder will be used as a soil reinforcement material
because gypsum contains silica oxide as a mineral adhesive which has better
properties than organic adhesives because it does not cause air pollution, is
inexpensive, fire resistant, is resistant to deterioration by biological factors and is
resistant to chemicals. The nature of gypsum powder which when added with water
will harden and is expected to increase the density of the soft soil so that its carrying
capacity will increase. Gypsum powder was mixed randomly with the soil with
gypsum content of 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18% and 20% of the
weight of the soil. This study was conducted to determine how the effect of adding
gypsum powder to the soil on the shear strength of the soil, maximum dry density
and CBR value. In addition, this study will also analyze the comparison of the
results of the soil shear strength parameters between the UCT and Triaxial UU
tests and analyze how the results of the laboratory UU Triaxial testing with the UU
Triaxial testing simulations carried out in the PLAXIS 2D 201701 program will be
compared.
The results of this study were the maximum dry density (ℽdmax) of the soil
decreased with the addition of gypsum powder where the highest ℽdmax was 1.60
g/cm3 while the lowest ℽdmax was 1.59 g/cm3. The value of shear strength (Su) from
the UCT test increased along with the addition of gypsum powder where the lowest
Su value was 0.90 kg/cm2 while the highest Su value was 2,98 kg/cm2, an increase
of 231%. The increase in the unsoaked CBR value of 285% and an increase in the
soaked CBR value is 377%. In addition, the addition of gypsum powder by 20%
resulted in an increase in the value of the shear strength (cu) of the Triaxial UU test
results of 339% from 1.05 kg/cm2 to 4.61 kg/cm2. The difference in the results of the
shear strength of the soil between the UCT and Triaxial UU tests produced is also
not very significant. The results of the Triaxial UU modeling with the modeling of
the hardening soil model in the PLAXIS 2D program are quite close to the results
of testing in the laboratory by producing relatively the same deviatoric stress
results at 15% of strain. | en_US |
