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Geomechanics and Engineering
  Volume 23, Number 2, October25 2020, pages 103-113
DOI: http://dx.doi.org/10.12989/gae.2020.23.2.103
 


Effect of nano-stabilizer on geotechnical properties of leached gypsiferous soil
Reza Bahrami, Navid Khayat and Ahad Nazarpour

 
Abstract
    Gypsiferous soils classified as problematic soils due to the dissolution of gypsum. Presence of gypsum in the soils texture subjected to steady flow can cause serious damages for the buildings, roads and water transmission canals. Therefore, researchers have conducted a series of physical, mechanical and microstructural laboratory tests to study the effect of gypsum leaching on the geotechnical properties of a lean clay containing 0%, 3%, 6%, 9%, 12%, and 15% raw gypsum. In addition, a combination of two nano-chemical stabilizers named Terrasil and Zycobond was used in equal proportions to stabilize the gypsiferous clayey samples. The results indicated that gypsum leaching considerably changed the physical and mechanical properties of gypsiferous soils. Further, adding the combination of Terrasil and Zycobond nano-polymeric stabilizers to the gypsiferous soil led to a remarkable reduction in the settlement drop, compressibility, and electrical conductivity (EC) of the water passing through the specimens, resulting in improving the engineering properties of the soil samples. The X-ray diffraction patterns indicate that stabilization by terrasil and zycobond causes formation of new peaks such as CSH and alteration of pure soil structure by adding raw gypsum. Scanning electron microscope (SEM) images show the denser texture of the soil samples due to chemical stabilization and decrease of Si/Al ratio which indicates by Energy dispersive X-ray (EDS) interpretation, proved the enhance of shear strength in stabilized samples.
 
Key Words
    gypsiferous soil; nano-stabilization; terrasil; zycobond; dissolution; microstructure
 
Address
Reza Bahrami: Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran

Navid Khayat: Department of Civil Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran

Ahad Nazarpour: Department of Geology, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
 

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