Date Approved

7-1-2020

Embargo Period

7-7-2020

Document Type

Thesis

Degree Name

M.S. Civil and Environmental Engineering

Department

Civil and Environmental Engineering

College

Henry M. Rowan College of Engineering

Advisor

Zhu, Cheng

Committee Member 1

Lomboy, Gilson

Committee Member 2

Montalbo-Lomboy, Melissa

Keywords

Bottom Ash Admixture, Crack Reduction, Desiccation Cracking, Digital Image Correlation, Image Processing, Microbial Induced Calcite Precipitation

Subject(s)

Fills (Earthwork)--maintenance and repair; Soil mechanics

Disciplines

Civil and Environmental Engineering | Geotechnical Engineering

Abstract

Desiccation cracking considerably impairs the hydraulic and mechanical properties of clayey soils and is critical to the long-term performance of infrastructure foundations and earth structures. Classical crack remediation methods are associated with high labor and maintenance costs or the usage of environment-unfriendly chemicals. Recycling waste materials and developing bio-mediated techniques have emerged as green and sustainable soil stabilization solutions. The objective of this study is to investigate the feasibility of soil crack remediation through the usage of microbial-induced calcite precipitation (MICP) and bottom ash admixtures. We carry out monotonic drying and cyclic drying-wetting tests to characterize the effects of bottom ash and MICP on the desiccation cracking of clayey soils. The desiccation cracking patterns captured by a high-resolution camera are quantified using image processing and digital image correlation techniques. We also resort to scanning electron microscopy for microstructural characterizations. MICP treatment improves the soil strength due to the precipitation of calcite crystals on soil particle surface and inside inter-particle pores. Adding bottom ash into clay reduces the plasticity of the mixture, promotes the flocculation of clay particles by cation exchange, and also provides soluble calcium to enhance calcite precipitations. This study demonstrates the potential of using bottom ash and MICP for crack remediation and brings new insights into the design and assessment of sustainable infrastructures under climate changes.

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