Electronic Thesis and Dissertation Repository


Doctor of Philosophy


Civil and Environmental Engineering


Professor Julie Q. Shang


Geomaterials can be often classified into two groups: virgin geomaterials such as soil and rock, and by-product materials such as mine tailings, coal fly/bottom ash, foundry sand, kiln dust, blast furnace/steel slag, reclaimed concrete and asphalt. Studies on these materials and their mixtures have been carried out extensively for geoengineering applications, including the characterization of mechanical properties such as the strength, compressibility, compactivity and permeability, as well as mineralogical and geochemical properties. The goal of this study is to investigate the thermal and electrical properties of selected geomaterials and their mixtures for enhancement of knowledge and engineering applications. The thesis consists of three parts as follows:

The first part presents the electrical conductivity measured on compacted kaolin clay using a circular two-electrode cell in conjunction with a specially designed compaction apparatus, which has the advantage of reducing errors owing to sample handling. The experimental results are analyzed to observe the influencing factors on the soil electrical conductivity. The performance of existing analytical models for predicting the soil electrical conductivity is evaluated by calculating empirical constants in these models.

The second part investigates the thermal and packing behaviors of mine tailings and tire crumbs mixtures in dry and wet states, which are important in engineering applications for utilizing recycled tire particles as lightweight fill materials with improved thermal insulation. The thermal and packing properties measurements of the mine tailings and tire crumbs mixtures with different mixing ratios are presented, which are then analyzed to establish the thermal properties relationships with respect to the mixing ratio of tire crumbs, porosity, bulk density, water content, compactive effort and tire crumbs size. The multiple linear regression analysis shows that the thermal conductivity of the dry and wet mixtures can be estimated using a general model consisting of the factors affecting the thermal conductivity.

The third part evaluates the thermal conductivity, compressive strength, elastic modulus and temperature changes of compacted mine tailings and fly ash mixtures during the curing period as functions of the fly ash ratio, molding water content and compaction energy. The microporosity structure of the fly ash treated mine tailings is also examined.