A novel electroosmotic chemical treatment for improving the clay strength throughout the entire region

• Published in: Applied clay science 2018-03, Vol.153, p.161-171
• Main Authors: Ou, Chang-Yu, Chien, Shao-Chi, Syue, Yu-Ting, Chen, Chun-Tao
• Format: Article
• Language: English
• Subjects: Chemical solutions; Electroosmotic chemical treatment; Full improvement; Polymerization effect; Pozzolanic reaction
• ISSN: 0169-1317; 1872-9053
• DOI: 10.1016/j.clay.2017.11.031

Electroosmotic chemical treatment can be used to improve clay strength. However, this improvement is often limited to regions near the anode and/or cathode, while the areas between the electrodes remain weak. The objective of this study was to develop a suitable method to improve the clay strength throughout the entire sample. The characteristics of the test clay were studied by varying the concentration of the calcium chloride (CaCl2) solution, injecting a potassium hydroxide (KOH) solution to neutralize the acidic conditions in the anode area, using a fresh sodium silicate solution in the anode compartment, and constantly injecting deionized water after injection of the sodium silicate solution. The results indicated that an increase in the concentration of the CaCl2 solution reduced the efficiency of injecting the sodium silicate solution in the subsequent treatment stage. The use of a fresh sodium silicate solution may increase the efficiency of injecting the sodium silicate solution into clay, thereby extending the improvement range. When deionized water was injected constantly after injection of the sodium silicate solution, the Ca2+ ions in the clay migrated toward the cathode during treatment and, simultaneously, a highly alkaline condition formed near the cathode, leading to an enhancement of the pozzolanic reaction and a significant increase in the clay strength near the cathode. Based on these results, an ECT test was conducted using a fresh sodium silicate solution and constant injection of deionized water. The results indicated that the strength of the entire clay sample was improved. •Use of fresh sodium silicate could improve the clay at the location far away from the cathode significantly.•Injection of water at the last stage increased the efficiency of cementation.•Injection of a certain combination of chemicals and then water can yield a full strength improvement over the entire sample.