Effect of Iron Oxide Coatings on Thermal Conductivity of Silica Sands

Abstract

Engineering properties of soils coated with naturally occurring or artificially manufactured particles can significantly differ from those of uncoated soils. This study aims at evaluating the effect of iron oxide coatings on the thermal conductivity of silica sands. Laboratory thermal needle probe tests were conducted on uncoated, goethite coated and hematite coated Ottawa 20/30 and Ottawa 100/200 sands. Test results demonstrated that the thermal conductivity (k) of all tested materials increases with increasing applied vertical stress, and the k of hematite coated sands was greater than that of uncoated sands under the similar relative density. However, the measured k of both uncoated and coated sands is a single function of porosity regardless of applied stress level, reflecting the limited effect of applied stress and iron oxide mineral coating on the k of tested materials. Simple resistances in series model was employed to explain the observed test results, and the results of this study was compared with k of previous studies on uncoated natural soils.