Degree

Doctor of Philosophy (PhD)

Department

Civil and Environmental Engineering

Document Type

Dissertation

Abstract

Traditional ground improvement techniques involve high energy consumption and expensive and invasive earthworks. To develop sustainable ground improvement techniques, extensive research has explored biological processes and strategies. This dissertation identifies two organisms, fungal mycelium and mud dauber wasp, as sources of utilization and inspiration for the development of sustainable soil improvement techniques.

Filamentous fungi can form a root-like interconnected complex network known as fungal mycelium. Fungal mycelium can extend through soil pores and secrete hydrophobic compounds, binding soil particles and increasing soil water repellency. This dissertation conducted experimental studies to investigate the effects of fungal mycelium on hydraulic and mechanical properties and erodibility of various types of soils. The results demonstrate that fungal mycelium can significantly increase attractive interparticle stress, shear strength, and soil water repellency and reduce water infiltration and hydraulic conductivity, improving erosion resistance of soils.

Mud dauber wasps construct soil nests to protect their offspring from predators, extreme temperatures, and rainwater. Mud dauber compacts the nest soils by producing a repetitive tapping using front legs and mandibles (similar to vibratory compaction in geotechnical engineering) and hardens the nest soils through atmospheric drying. This dissertation investigates the mechanical and thermal properties of mud dauber nests, to assess the effectiveness of the nest construction techniques (repetitive tapping and atmospheric drying) used by mud daubers in improving soil properties. The results show mud dauber nests exhibit high density, modulus, and strength, and low thermal conductivity, demonstrating the effectiveness of the nest construction techniques for soil improvement. Furthermore, this dissertation discusses the potential of mud dauber nest construction techniques for sustainable development in earthen building construction.

Date

1-11-2024

Committee Chair

Hai Lin

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