Testing surfactants as additives for clay improvement: compaction and suction effects

Nathan Jones,Sérgio D.N Lourenço,Alison Paul,P Delage,Y.-J Cui,A.-M Tang,J.-M Pereira,S Ghabezloo

doi:10.1051/e3sconf/20160913006

Nathan Jones, Sérgio D.N Lourenço + Show 6 more

Open Access

https://doi.org/10.1051/e3sconf/20160913006

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Abstract

This paper presents an exploratory study on surfactants as additives to improve soil properties. It is hypothesized that surfactant molecules populate the air-water interfaces reducing surface tension and suction thus allowing a control of the mechanical response of the soil. Suction measurements by means of a high suction tensiometer, compaction tests and Atterberg limits were conducted in mixtures of sand and kaolin, with and without a surfactant solution. The results revealed a prominent effect on suction, but to a lesser extent on the Atterberg limits and compaction behavior (the maximum dry density). This targeted effect of the surfactants suggests its molecules populate, not only the air-water interfaces decreasing surface tension, but may be adsorbing to the clay particles and forming micelles in the pore water as well. Therefore the interplay between the three may influence the soil behavior.

Highlights

Surfactants molecules consist of one polar, hydrophilic head group and one non-polar, hydrophobic tail group
To determine the consistency behavior, the liquid limit (LL) was obtained following the Cone Penetrometer Method (BS1377:Part 2:1990:4.3) with LL corresponding to a penetration of 20 mm while the plastic limit (PL) followed BS1377 with PL obtained for a water content of a thread of soil that crumbles at 3 mm
The plastic limit increased from 35.1% to 42.6% while for the 25% kaolin sample, the

Summary

Introduction

Surfactants molecules consist of one polar, hydrophilic head group (water-loving) and one non-polar, hydrophobic tail group (water-hating). Surfactants have an affinity for a surface, forming into an orientated monolayer at the interface and reducing the interfacial tension. When the surface has no more space they begin to self-associate to form aggregates inside the bulk of the liquid (micelles). Micelles typically contain between 20100 surfactant molecules. The concentration of surfactants, at which micelles begin to form, is defined as the critical micelle concentration (CMC). The CMC depends on surfactant type/chemistry, temperature (Rosen, 1989) among other factors

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Conclusion