The clay-concrete interface is very common in various construction settings such as in pipelines buried in soil, piles in soft soil, earthen dams made up of compacted clay as inner core, etc. Polymer have found diverse applications across industries, including construction sector as soil stabilizers, structural coatings, component of geomembrane and geotextiles. The contact area/surface between fine grained soil (clay) and structural material such as cement/concrete requires meticulous attention during the design stage. The work focuses on developing an interface between clayey soil and cement substrate applying a non-acrylic polymer coating. Contrary to the usage of Optimum Moisture Content (OMC) as a field practice, our findings indicate that a moisture to the dry of optimum exhibits superior interfacial adhesive strength. The presence of distinct pore microstructure in clay and the subsequent impregnation of polymer to these pores giving rise to mechanical interlocking were considered the contributing factor for this enhanced strength. In addition to this, surface free energy measurements on clay surface at different moisture content doesn’t show any appreciable difference, thereby confirming the role of mechanical interlocking of polymers as the driving factor.
In addition, we investigated the effect of organic modification of clay on interfacial performance of epoxy coatings applied to the clay surface. By tuning the clay surface to organophilic using suitable agents, it can be made more compatible with polymers. A similar methodology was adopted and the interfacial adhesion characteristics of the modified clay system is assessed. Unlike in Polymer-Nanocomposites (PNC’s), the modifiers, in this case, have a detrimental effect on the strength due to the blockage of clay surface pores, a phenomenon confirmed through porosity estimation using Mercury Intrusion Porosimetry (MIP) studies. Additionally, we evaluated the influence of the the proximity of cement substrate on the interfacial strength. Notably, the clay-epoxy interface behaviour was altered because of the competetive interaction between cement and unpolymerised epoxy resin for DETA (diethylenetriamine). Detailed insights based on XPS and FT-IR studies will be discussed in the seminar.