Water-soluble polymers are of growing importance in the field of geotechnics. The term polymer is used to describe long-chain macromolecules consisting of several repeating units. Based on this general definition, the term covers a wide range of natural molecules, bacterial and synthetic products that are omnipresent in the natural and man-made environment. For geotechnical engineering, polymers have the potential to increase the resistance of geotechnical building materials to destructive environmental conditions, to sustainably replace inorganic binders for the treatment of soils or to improve or replace mineral building materials. The use of polymers to control and improve the physico-chemical, hydraulic, and mechanical properties of soils has proven to be versatile and promising for various geotechnical and geoenvironmental applications. Although the use of polymers has left the stage of feasibility studies well behind it, the wide range of possible applications and consequent innovations are constantly stimulating new research. However, at the same time, there is an ongoing need for research for applications already established in geotechnical practice, not least due to the complexity of potential polymer-clay interactions.
We are therefore delighted to present this themed issue which addresses the latest developments in research and practice using polymers to control soil properties.
The themed issue includes a number of articles dealing with the hydro-mechanical properties of modified geosynthetic clay liners (GCLs). Li et al. (2024) studies the relationship between the effective stress and permeability of modified GCL when exposed to combustion product leachate. Mazzieri and Bernardo (2024) investigate dense prehydrated GCLs with regard to their permeability and retention properties when exposed to heavy metals. Khan et al. (2024) presents the water retention properties of modified GCLs using the filter paper method. Chen et al. (2024) evaluates the shear strength of geosynthetic clay liners made of bentonite-polymer composite. The last paper in this thematic block is Geng et al. (2024a), who analyses the reliability of index tests to assess the barrier performance of modified bentonite.
The research papers by Nie et al. (2024) and Geng et al. (2024b) address modified bentonite based on a multiscale approach. Nie et al. (2024) address the swelling and consolidation behaviour of modified bentonite when exposed to cationic solutions and outline the effects of polymers on mineralogy. Geng et al. (2024b) provide an approach to link the hydraulic conductivity of modified bentonite to the morphological characteristics and viscosity of polymers embedded in intergranular pores.
In addition to this thematic focus on modified clay and geosynthetic clay liners, also research on modified sand is presented in the current themed issue. Sarkar et al. (2024) studied the potential of polymer solutions to serve as an innovative additive for the limitation of wave propagation. Chang et al. (2024) presents findings on the wetting and drying behaviour of Sand modified by using biopolymer.
We are delighted about this thematic richness and thank all the researchers contributing to this themed issue.
