Technical NoteUndrained cyclic loading response of lignosulfonate treated high plastic clay
Introduction
Traditional chemical additives such as cement, lime, gypsum, etc have been used effectively to enhance the compressibility and strength characteristics of problematic soils. However, the use of such chemical stabilizers are not readily acceptable as they create serious environmental problems such as altering pH level, limiting the scope of vegetation, affecting the yielding capacity of soils, and reducing the quality of the groundwater [[1], [2], [3]]. Moreover, soil stabilization using traditional admixtures makes the soil excessively brittle which is undesirable in case of structures subjected to cyclic loading such as highway embankments and rail tracks [4,5]. In order to overcome these problems, a lignin-based chemical, lignosulfonate (LS) has been recognized as an alternative stabilizer in recent years and its application has been explored for stabilization of problematic soils [[6], [7], [8], [9]]. Lignosulfonate (LS) is a non-toxic and non-hazardous environmental friendly chemical that enhances the strength and stiffness without affecting the ductility of the host soil [8].
Although research studies have reported the benefits of LS stabilized soil; however, most of the studies are carried out for static tests such as unconfined compressive strength tests and improving the physical properties of soil. In the present study, a series of static and cyclic triaxial tests were conducted to evaluate the effectiveness of LS treated high plastic clay for different parameters such as unconfined compressive strengths (UCS), undrained shear strength, deformation characteristics i.e., total and plastic strain behaviour and resilient modulus of the test soil. In addition, the influence of lignosulfonate stabilization on the rate of axial deformation has been investigated to illustrate the longevity of LS treated soil under cyclic loading.
Section snippets
Material properties
A high plastic clay (CH) was collected for the present investigation and preliminary tests were conducted to determine its basic physical properties as detailed in Table 1. The soil contains approximately 30% clay, 59% silt and 11% fine sand. The maximum dry unit weight and optimum moisture content were found to be 16.8 kN/m3 and 20.7% from standard proctor test. The physical and chemical properties of lignosulfonate used to stabilize the selected soil in the present study are also presented in
Unconfined compression test results
Fig. 1 presents the variation of axial stress with axial strain for stabilized soil samples at different percentages of lignosulfonate dosages i.e., 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% and curing periods. The compressive strength of treated soil specimens increased with increase in lignosulfonate content up to an optimum dose of 2.0% and then decreased with further increase in LS content; however, compressive strength increased continuously with curing period. The unconfined compressive strength
Conclusions
In this paper, the influence of lignosulfonate stabilization on the high plastic clay was investigated under static and cyclic loading for soil specimens compacted at dry side of optimum moisture content. The unconfined compressive strength of soil specimens increased with increase in the lignosulfonate content up to an optimum content of 2.0%, which decreased with the further addition. The increase in UCS values was found to be dependent on both lignosulfonate content and curing time. The
Author statement
Avinash Kumar Singh: Conceptualization, Methodology, Investigation, Data Curation, Validation, Writing - Original Draft.
Jagdish Prasad Sahoo: Conceptualization, Methodology, Formal analysis, Writing - Review & Editing, Supervision.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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