Understanding the role of Ca2+, Na+ on swelling behaviour of natural expansive soils: a field application perspective

Abstract

Swelling behaviour is the prime hindrance for effective utilization of expansive soils as a geomaterial. To alleviate such behaviour, stabilization with a suitable additive is essential. However, the current practice of additive and stabilization selection technique to treat the expansive soils predominantly relies on geotechnical properties, in particular on consistency limits. The present paper aims at demonstrating the role of chemical constituents on swelling properties in a comprehensive way. Elaborate tests to determine the swelling and chemical constituents are carried out, and based on the obtained results, interrelations between them are developed. The analysis of results revealed the maximum swelling occurrence at NaT of 0.4�0.7%, CaT of 4�5.5%, total CEC of 45�70�meq/100�g, and (Ca/Na)T of 15.75, respectively. The results portray that swelling in clays is minimal when NaT < 0.2%, CaT > 5.5%, and total CEC < 20�meq/100�g, delineating a fact that additive selection is highly effectual and economical for those soils that comprise constituents in these prescribed limits. The results provided in the study fetch two major benefits: first, likely avoidance of overdose usage of stabilizer content, and second, economization of the cost of stabilization by predicting the most appropriate additive. Such kind of in-depth studies is indeed imperative to decide the direct applicability or to choose an appropriate stabilizer to amend expansive soils, such that the treated soil qualifies as a geomaterial in the construction of earthen structures. � 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.