Abstract:
ABSTRACT
Expansive soils are soils that have a tendency to undergo significant changes in
volume due to variations in moisture content. The volume changes in expansive
soils may result in heaving and cracking that lead to infrastructure damages
worth several billions of dollars each year all over the world. In recent years,
there has been a growing interest in chemical stabilization to treat the
engineering characteristics of soil such as swelling, strength, and volume
stability. It was used chemical material environmentally friendly, sustainable,
and low-cost building materials that originate from various sources it's called
Geopolymer. The present work's aim was to study the effect of adding five
percentages of Metakaoline based-Geopolymer (MK) to expansive soil
(0.3%,1%,2%, 4%, and 6%) with an activator ratio of 20% for the weight of dry
soil at curing period (0day,7days, and14days). The expansive soil used in the
present work was brought from the Governorate of Al-Anbar /Iraq. A number
of laboratory tests have been carried out which were, including one-dimensional
consolidation tests, shear strength tests, and physical tests. Additionally,
Scanning Electron Microscope (SEM) and X-ray diffraction (XRD)tests were
done. The swelling results showed that the addition of MK had an impact on the
swelling reduction, which was reduced by about 91% with 4% MK at 14 curing
days. Additionally, the optimum moisture content decreased from 23 to 18%
with 4% Metakaolin, while the maximum dry density increased from 15.2
kN/m3 to 16.9 kN/m3. The peak value of unconfined compressive strength rises
to (11) times the original soil for 4% MK with cured for 14 days. Moreover, the
results of SEM and XRD illustrate the reaction of the clay with Geopolymer led
IV
to the production of binder particles and the create of cementitious particle from
interactions.
Finally, the stabilization of expansive soil with MK was a successful
method and gave good results, it can be considered 4 % MK the best percentage
of improvement expansive soil.
