PERFORMANCE OF CALCIUM LIGNOSULFONATE AS A STABILISER OF HIGHLY EXPANSIVE CLAY

MARIANO TOMAS FERNÁNDEZ; SANDRA ORLANDI; CODEVILLA, MAURO; PIQUÉ, TERESA MARÍA; MANZANAL, DIEGO

Transportation Geotechnics

Elsevier Ltd.

Año: 2020

2214-3912

The efficiency of calcium lignosulfonate (CLS) as an expansive soil stabiliser wasstudied. CLS is a bio-based polymer, obtained as a sub-product of the paper industry. Itsuse as a soil stabilizer not only enhances the properties of the soil but also eliminates theeconomic and environmental costs of its disposal. In this project, CLS was added to anatural smectite clay (Clay) from Comodoro Rivadavia, Argentina. Smectite clays exhibitsignificant plastic volumetric deformations when subjected to moisture variations. Claywas stabilised using 3.0 and 5.0% mass of CLS. The efficiency of CLS as a stabilisingagent was measured studying its influence on the physical properties of Clay (Atterberglimits, Cation Exchange Capacity, Specific Surface Area). Considerable reductions of thecation exchange capacity (CEC) and the specific surface were registered. Furthermore, afull hydro-mechanical characterisation of Clay with CLS was performed in saturated andunsaturated conditions. Results from free swell and swelling pressure tests show that CLSreduces by nearly a half and nearly a quarter the free swell and swelling pressure of Clay,respectively. Additionally, mercury intrusion porosimetry (MIP) and scanning electronmicroscopy (SEM) tests were carried out to evaluate the microstructure re-arrangementof Clay when CLS was added. Results showed that a relatively small amount of CLSmight yield a reasonably satisfactory performance as a stabiliser, particularly in reducingthe natural Clay?s swelling potential. Moreover, CLS induced an increase in the stiffnessand strain at failure of Clay and a reduction in its porosity.