Abstract
The effects of a sulfonated oil (SO) stabiliser on the swell–shrink properties of an expansive soil were investigated through cyclic wetting–drying tests. The cyclic wetting–drying action led to the reconstruction of the soil microstructure by inducing clay particle aggregation. Accordingly, the greater the number of applied cycles, the lower the swell–shrink potential up to the fourth cycle, beyond which the swelling and shrinkage strains attained elastic equilibrium. At any given cycle, the tendency for swell–shrink reduction was in favour of the SO concentration up to 0·75%, beyond which the excess SO molecules self-associated in the form of aggregates, thereby acting as a ‘lubricant’ rather than a clay-stabilising agent. As a result of SO treatment, the accumulated axial strain progressively transitioned towards a desirable, ‘neutral’ state, with 0·75% SO exhibiting the highest resistance against cyclic wetting–drying. For any given SO concentration, the equalised void ratio–moisture content curves for wetting and drying followed the same S-shaped path, further corroborating that the swelling and shrinkage processes, on achieving elastic equilibrium, become reversible. The shrinkage and liquid limits indicated a progressive transition towards a desirable, aggregated fabric, with 0·75% SO identified as the optimum concentration.
Highlights
In arid and semi-arid climates, the design and construction of infrastructure are often adversely affected by the presence of expansive/reactive soil deposits
In view of the limited and inconsistent literature on employing sulfonated oils (SOs) in ground improvement practice, the work reported in this paper examined the performance of a commercial SO stabiliser as a sustainable solution towards mitigating the swell–shrink volume change potential of an expansive soil
The use of 0·75% SO promoted a 51% improvement/reduction in the swelling potential at N = 2 (SWP decreased from 21·2% for SO0 to 10·5% for SO0·75), while a lower improvement of 26% was achieved for the same SO concentration at N = 5 (SWP decreased from 13·4% for SO0 to 9·9% for SO0·75)
Summary
In arid and semi-arid climates, the design and construction of infrastructure are often adversely affected by the presence of expansive/reactive soil deposits. The problems associated with expansive soils are often alleviated by means of various soil stabilisation techniques, which refer to a group of mechanical, chemical or combined mechanical–chemical practices capable of amending the soil fabric into a coherent matrix with improved shear strength and reduced swell–shrink volume change potential (Soltani et al, 2017; Winterkorn and Pamukcu, 1991) In this regard, the use of cementitious/calcium-based binders, such as cement and lime, still remains the most well-established and timetested soil stabilisation scheme practised over past decades (e.g. Al-Rawas et al, 2005; Estabragh et al, 2013, 2014; Garzón et al, 2015, 2016; Jha and Sivapullaiah, 2016; Nalbantoglu and Tuncer, 2001; Phanikumar and Nagaraju, 2018; Rao et al, 2008; Sharma and Sivapullaiah, 2016; Soltani et al, 2017; Thyagaraj and Zodinsanga, 2014). The basic principles of chemistry, in conjunction with the soil mechanics framework, were employed to identify the clay SO-amending mechanisms, and to predict and perceive the evolution of the soil fabric in response to alternate wetting and drying
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