Date

2013

Document Type

Dissertation

Degree

Doctor of Philosophy

Department

Civil Engineering

First Adviser

Pamukcu, Sibel

Other advisers/committee members

Suleiman, Muhannad; SenGupta, Arup; Ferguson, Gregory; Pervizpour, Mesut

Abstract

Engineered soils are geo-materials with designed mechanical, physical, and chemical properties to address practical problems in geotechnical and geo-environmental applications. This research focused on the development of an innovative "smart soil", and centered the fundamental understanding of capillary effects, mechanical properties, and conduction behaviors of this new material with the emphasis on reversible surface wettability.Surface-initiated atom-transfer radical polymerization (ATRP) technique was explored to synthesize engineered soils coated with a thermally sensitive polymer. Several surface characterizations were used to verify the surface modifications. Particle-level observations revealed the influences of the particle-fluid interactions and pore space liquid distribution on particle connectivity and propagation-path establishment in porous media with different wettability. A numerical simulation was conducted to analyze the capillary pressure and capillary forces applied at particle contact with various volumes of liquid bridge. Complementary shear-wave-velocity tests captured the "cementing" effect induced by capillarity at low degrees of saturation of water for hydrophilic soils. Finally, thermal and electrical properties of engineered soils with different wettabilities were analyzed experimentally at varying degrees of saturation to gain an enhanced understanding of effects of particle-water interaction on thermal and electrical conduction behaviors. Hydraulic transport responses under three conditions were studied to examine the influences of surface properties on flow performances - dry soil water infiltration, saturated flow, air imbibition and gravity drainage.

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