| dc.description.abstract | MX-80 bentonite was used for the erosion test. The turbidity of the liquid was measured from the water outlet of the device to estimate the erosion quality. The average radial expansion distance and the area of accessory minerals were measured by the image, analyze the influence of different aperture, water chemistry and water flow on the erosion of bentonite.
The most serious erosion was observed using deionized water in a large aperture (2.0 mm) and a high flow rate (1.0 mL/min) environment. 30.8% of the original weight has been lost at 93 days , And the ionic strength of 2.54 mM and 4.00 mM NaCl solution, the eroded mass measured in 63 days is less than 1.0% of the original weight. The ionic strength of groundwater is the key to the erosion of bentonite. In the test of deionized water with a flow rate 1.0 mL/min and a 0.2 mm aperture, the eroded mass measured at 93 days is equivalent to the loss of 3.68% of the original weight, so the eroded mass will decrease with the aperture. In the test of deionized water with a flow rate 0.2 mL/min and a 2.0 mm aperture, the eroded mass measured at 104 days is equivalent to the loss of 8.84% of the original weight. When a lower water flow rate is used, the eroded mass will reduce significantly.
Observe and analyze the image and the bentonite sample after the erosion test. It is believed that the formation of the accessory mineral ring is whether erosion occurs. If a large amount of montmorillonite is lost after bentonite erosion, the coarser particles staying in place will block the medium-sized and fine particles, These particles will be blocked by bridging. The bridging will jam each other in place, and eventually form a accessory mineral ring.
From the results, it is known that the large water flow and aperture will cause severe erosion. The impact of water chemistry is the most critical. In the test of 4.00 mM NaCl solution, buffer will maintain barrier function. | en_US |