ORIGINAL PAPER Stabilization of expansive soils using ionic stabilizer Sharif Arefin 1 & Hussein Al-Dakheeli 1 & Rifat Bulut 1 Received: 10 June 2020 /Accepted: 5 March 2021 # Springer-Verlag GmbH Germany, part of Springer Nature 2021 Abstract In many parts of the USA, expansive soils pose a significant hazard to infrastructures. These kinds of soils owe their character- istics to the presence of swelling clay minerals. As they get wet, they swell; conversely, as they dry, they shrink. Many stabilization methods have been developed to mitigate the adverse effects of expansive soil. One of them is the use of the ionic additive. In this research, a liquid ionic product is evaluated as a non-traditional stabilizer. Soil samples from a specific con- struction site in Texas and soil samples from Oklahoma were utilized. The evaluation tests involve the suction measurements, swelling, and plasticity index for treated and untreated soils. Cyclic swelling tests were also carried out on reconstituted specimens. From laboratory tests and analysis, it was found that this additive is effective in reducing swelling of both Texas and Oklahoma soils. It reduces swelling of Texas soils by 0.4–6% and Oklahoma soil by 2–7.4%. The results of swelling cycles reveal a permanent effect of this stabilizer on mitigating the swelling behavior. After the 3 rd swelling cycle, the swelling for Oklahoma soils was 5.58% lower than the natural soil, and for Texas soils, it was reduced by 6.02–8.49% for different concentrations of the additive. However, no definitive trend was observed for reducing the shrinkage potential. Keywords Expansive soil . Soil stabilization . Ionic stabilization . Swelling . Shrinkage Introduction “Stabilization” refers to process where the engineering prop- erties of the soil have been changed significantly (Kalidas 2014). There are two primary types of soil stabilization used today—mechanical stabilization and chemical stabilization. Mixing chemical additives with soil which changes the chem- ical properties of the soil, thereby upgrading its engineering properties, is known as chemical stabilization (Kalidas 2014). Traditionally, the addition of cement, lime, bituminous, or other agents is referred to as a “chemical” or “additive” meth- od of soil stabilization (Kalidas 2014). Lime is the oldest sta- bilizer used in the world (Qingquan et al. 2004). Cement was first used as a stabilizer in the twentieth century (Azzam 2014). Other traditional stabilizers include fly ash, gypsum, slag, alum, kiln dust, and stone dust (Zahri and Zainorabidin 2019). But, unfortunately all of these products have been re- ported to have detrimental effects on the environment related to carbon dioxide (CO 2 ) emission and poor performance dur- ing seismic activities (Zahri and Zainorabidin 2019). These issues have led the experts in using some new types of non- traditional stabilizers which are suitable, economical, and come in liquid or powder form (Arabani et al. 2012). These chemical stabilizers can work in different ways — encapsulation of clay minerals, exchange of interlayer cations, breakdown of clay minerals with expulsion of water from the double layer, and interlayer expulsion with subsequent mois- ture entrapment (Petry and Das 2001). Additives that work by exchanging interlayer cations (also known as ionic stabilizer) stabilize soil by the addition of certain ionizable salts in an aqueous concentration (Graf 1976). In the field, the aqueous solution is distributed throughout the soil by physical diffu- sion and mass flow (Graf 1976). These chemical stabilizers are usually sold as concentrated liquids and diluted with water at the construction site (Katz et al. 2001). Although these non- traditional soil stabilizers have potential advantages over tra- ditional additives, professionals are reluctant to specify the use of these products due to several reasons like the lack of pub- lished studies and field performance data. * Sharif Arefin sharif.arefin@ttu.edu * Hussein Al-Dakheeli abedalm@okstate.edu * Rifat Bulut rifat.bulut@okstate.edu 1 School of Civil and Environmental Engineering, Oklahoma State University, Stillwater, OK 74078, USA https://doi.org/10.1007/s10064-021-02179-5 / Published online: 8 March 2021 Bulletin of Engineering Geology and the Environment (2021) 80:4025–4033