A study of the effects of electrode spacing on the cementation region for electro-osmotic chemical treatment

• Cementation often occurs near cathodes where pH values are higher than 8.3 to 8.7.
• The cementation region was related to applied voltages and electrode spacing.
• The cementation region was little related to the size and shape of cathodes.
• Cementation region can be predicted with the initial current.

Previous laboratory studies have shown that injection of the calcium chloride solution can cause soil to be cemented near the cathode during electro-osmosis. In order to predict the size of the cementation region, a series of electro-osmotic chemical tests was conducted using different electrode sizes, electric voltages, and electrode spacing. After the tests, the concentration of calcium ions and pH values over the entire sample were analyzed and the cementation near the cathodes was inspected. Results show that the contours of the Ca2 + concentration, contours of the pH values and the cementation region were consistent to each other. Cementation often occurs near the cathode in an alkaline environment where the pH values are higher than 8.3 to 8.7. The cementation region was highly related to the applied voltage and electrode spacing but slightly related to the size and shape of the cathodes. When the electric field intensity was amplified by N times, the radius of the cementation region was increased by N times. This relationship can be used to predict the cementation region around the cathode and to design a rational spacing between two cathodes for multiple pairs of electrodes.