Plasticity and Swell-Shrink Behaviour of Electrokinetically Stabilized Virgin Expansive Soil using Calcium Hydroxide and Calcium Chloride Solutions as Cationic Fluids

Abstract

This investigation focussed on the plasticity and swell-shrink behaviour of an expansive soil that was stabilized using electro kinetic stabilization (EKS) techniques with cationic fluids for enhancement of stabilization. 0.25 M solutions of calcium hydroxide and calcium chloride were used as cationic fluids. An electro kinetic (EK) cell of dimensions 500 mm x 150 mm x 160 mm with inert graphite electrodes of size 140 mm x 160 mm x 5 mm was adopted for the stabilization process, carried out at an applied voltage of 40 V over a period of 6 hours. After the duration of the test, stabilized soil sample was subjected to Atterberg limits and free swell tests to determine its plasticity and swell-shrink characteristics. The results of the investigation found that both fluids were capable of reducing the plasticity and swell-shrink behaviour of the soil with different levels of effectiveness.

Voltage optimization in expansive soil improvement with saline solution on swelling and shear strength

“…Of the four large voltages given, there was a change in the value of soil density (GS), liquid limit (LL), plastic limit (PL), plasticity index (PI), and shrinkage limit (SL). Injection with CaCl2 caused a decrease in LL, PL, and PI values [10]. The injected soil with a voltage of 12V, 15V, 18V, and 24V is classified by USCS are clay with moderate plasticity (CL).…”

“…There was a soil shear-strength increase in the expansive soil that had been injected with CaCl2 at the anode [6]. Electrokinetic with CaCl2 injection reduced the LL, PL, and IP values and had an effect on the swelling potential of the soil [9][10][11][12][13]. The electroosmosis process causes the movement of water from the anode to the cathode, and CaCl2 is simultaneously injected, hence, there is a change in physical and mechanical properties, mineralogy of the soil, and a decrease in each certain distance.…”

“…Expansive clay has montmorillonite with a 2:1 mineralogy structure between silica (SiO2) and alumina (Al2O3), has a positive charge (cation) between the mineralogy sheets which results in easy exchange capacity [6][7][8]. Divalent cations bind more strongly to the clay surface than monovalent cations, following a typical exchange sequence such as Na + <Li + <K + <Rb + <Cs + < Mg 2+ <Ca 2+ <Ba 2+ <Cu 2+ <Al 3+ <Fe 3+ <Th 4+ [2,[9][10]. The saline solution used IOP Publishing doi:10.1088/1755-1315/1263/1/012050 2 for electrokinetics is known that better consolidation efficiency can be achieved by using CaCl2 Because the exchange capacity in the double electric layer and hydration capability of cations is different, CaCl2 is able to provide a greater enhancement of electroosmotic consolidation than KCl and NaCl [6][7][8][9].…”

“…Electrokinetic injection has the ability to change the physical and mechanical properties of the soil by reducing the LL, PL, and IP values, swelling potential, and changing the shear angle and cohesion values of the soil [9][10][11]. In addition, the mineralogy of the soil also changes due to the chemical injection process [12].…”

Expansive Soil Improvement Using Electrochemical Injection

“…Electrokinetic is one of the methods that can be used to improve fine-grained, soft and swollen soils. [11][13][14] [12] This method is possible due to the presence of clay particles in the soil with low permeability, certain mineral properties, electrical and chemical activity. Low permeability soils are expanded soils, dispersed soils, highly compacted clays, marine clays, sensitive clays, quick clays, saline/sodium soils, soft peat and other soils.…”