Polymer Solution–Clay Interaction Effects on Contaminant Barrier Material Integrity: Part II—Damage Parameters

摘要

Textural changes can manifest in emplaced barrier materials for contaminants in response to their stabilization with aqueous polymers against desiccation stresses that can induce cracking. In this Part II of the two-part article, experimental studies of clay and sand/clay barrier materials were performed to determine their shrinkage, drying rate (DR), and cracking patterns when admixed with aqueous polymers such as polyvinyl alcohol, polyethylene oxide, carboxymethyl cellulose, and chitosan. Aqueous concentrations used were in the range of 0–5 g/L, and DR tests were performed at 25°C and 30% relative humidity. Shrinkage tests were performed at 75°C. As evident in the shrinkage results for chitosan and polyethylene oxide with 90:10 mixture of sand:montmorillonite, high aqueous polymer content may not necessarily translate to greater resistance to barrier material shrinkage. Results show that almost all polymer-amended barrier samples exhibit better shrinkage characteristics (low shrinkage ratio and high shrinkage limit) than those mixed with distilled water. Polymer chain length does not correlate positively with shrinkage parameters. The DR curves show greater retention of aqueous polymer solutions than distilled water in desiccating barrier materials after 10 h of drying. At any concentration between 0 and 5 g/L, only polyvinyl alcohol can be considered to be a crack inhibitor.