Chemical grouts to reduce contaminant leaching from deep vadose zone sands

This research evaluates the effectiveness of epoxy and polyurethane resins used as grouts to mitigate iodide leaching from deep vadose zone sands. The research measured the rate of gas evolution during grout curing, foam expansion, and the effectiveness of each grout in trapping iodide within the sand matrix. Minimal iodide displacement during grouting is desired and the polyurethane grouts displaced <1 % of iodide due to moisture in the samples being consumed by reactions with methylene diphenyl diisocyanate, leaving little excess moisture and associated mobile iodide as the resins cured. Nearly half (45 %) of the iodide was displaced during the injection of epoxy grout when moisture was present. This was attributed to the immiscibility of water containing iodide with epoxy, which was displaced from the monoliths during grouting. Minimal porosities and diffusivities are desired after grouting and all polyurethane grouts had porosity values ranging from 16.59 % to 19.45 % and diffusivities between 1.84×10^-8 to 2.30×10^-7 cm²/sec. Catalyzed grouts generally showed lower porosity and diffusivity with higher ratios of added catalyst.