2. Research Content and Results
Test Materials

Test Methods
Basic Sample Parameters:
Dry Density: 1.9 g/cm3
Bentonite Content: 70%
Diameter: 50 mm
Height: 150 mm

Test Results

•The hydration rate of the sample decreases with increasing distance from the water injection end

•Compared with distilled water, the lead nitrate solution permeates faster

•The total axial strain is greater than the vertical swelling strain at different positions
•The closer to the water injection end, the greater the swelling deformation
 

•The vertical swelling deformation is greater than the horizontal swelling deformation

 •Most of the Pb(2+) is adsorbed and immobilized at the water injection end of the sample

 •Hydration is more complete near the water injection end, resulting in an increase in small pores and a decrease in large pores

3. Main Conclusions
  1) The hydration rate of the GMZ bentonite-sand mixture decreases significantly with increasing distance from the water injection end. Compared with distilled water, the chemical solution permeates faster in the sample, mainly due to the inhibitory effect of solution ions on the thickness of the double electric layer.

2) The axial swelling strain of the mixture reaches as high as 7.57%, while the radial swelling strain is relatively small. Moreover, compared with the vertical direction, the horizontal swelling strain at the same distance is smaller.

3) The GMZ bentonite-sand mixture can use its strong adsorption capacity to immobilize Pb(2+) at the water injection end of the sample and prevent it from further diffusing into the interior of the sample.

4) The closer the sample is to the water injection end, the more complete the hydration, which leads to a significant decrease in large pores and a marked increase in small pores.

(Source: Department of Geotechnical Engineering, Tongji University, Jia Lingyan)