Ground improvement using electro-chemical injection

Abstract This research presents a recent technique called Electro-Chemical Injection (ECI), which is used to stabilize the ground. ECI provide an innovative method in geotechnical and environmental engineering for ground improvement or stabilization of soft or fine-grained soil. The main principles of the ECI are combinations of four electrokinetic phenomena in soils consist of electroosmosis, electromigration, and electrophoresis. ECI is performed by injecting chemical substances into soil which is under an electric field application. The cross transport of stabilizing agents through the soil will cause chemical reactions which will result in physicochemical and cementation effects that enable to modify microscopic structures of soil, surface bonding, and inter-particle attractions, in such a way that the shearing strength of the soil can be increased. Other processes also occur simultaneously during treatment such as electrolysis, dissociation, sorption, exchange mechanisms etc. A bench scale of the ECI system was carried out to perform laboratory experimental work. Fifteen ECI experiments were conducted in laboratory. The calcium, Ca2+ (in CaCl2 solution); potassium, K+ (in KCl solution); and ferrous, Fe2+ (in FeCl2 solution) were used respectively in the anolyte solutions. The other chemical species such as carbonate, CO3 2- (in Na2CO3 solution); hydrogen phosphate, HPO42- or phosphate, PO43- (in K2HPO4 solutions); and soda water were used respectively in the catholyte solutions. During the treatment period, both the anolyte and catholyte were given no chemical conditioners, and they were maintained at constant levels in the electrode compartments. The results of the bench scale experiments showed that, the shear strength of soil after ECI treatment increased up to 1,000%.