Geotechnical characterization of a fine-grained soil potential for landfill liner application

Date of Publication

3-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Subject Categories

Civil Engineering | Engineering | Geotechnical Engineering

College

Gokongwei College of Engineering

Department/Unit

Civil Engineering

Thesis Advisor

Dr. Mary Ann Q. Adajar

Defense Panel Chair

Dr. Jonathan R. Dungca

Defense Panel Member

Dr. Mario P. de Leon

Dr. Erica Elice S. Uy

Dr. Vergel C. Bungay

Dr. Lessandro O. Garciano,

Abstract/Summary

This geotechnical investigation of a fine-grained soil is to determine its suitability as a sanitary landfill liner, as an alternative earthen material, or as a component in a composite liner system. The soil's index and mechanical properties, morphological, mineral, and elemental composition are determined. The fined-grained soil is elastic silt as per the Unified Soil Classification System (USCS) with a small 2% of fine sand and 98% majority of fines. The crystal phases of kaolinite, biotite, antigorite, and goethite comprise the soil sample from the XRD result. The Scanning Electron Microscopy (SEM) reveals flakey, spheroidal, tubular morphological attributes and intergranular voids usually associated with clay minerals. The energy-dispersive X-ray spectroscopy (EDS) result indicates the presence of phyllosilicates. The hydraulic conductivity ranges from 1.98x10-6 to 1.0x10-7 cm/sec meets the regulatory requirement for sanitary landfills in many countries. The unconfined compressive strength (UCS) test yields values ranging from around 125 kPa to 450 kPa with most values over the acceptable value of 200 kPa. The volumetric shrinkage strain (VSS) test result ranges from over 2.97 % to 11. 17 % with most measured values above the 4% limit. The breakthrough time estimates for Chemical Oxygen Demand (COD) range from 5.39 years to 45.82 years with substantial estimated values less than the minimum 30-year threshold. A superposed plot of the replots of the zones that meet the design criteria for low hydraulic conductivity, UCS, and VSS yielded an intersection of the hydraulic conductivity and unconfined compressive strength only. The formulated empirical models for the compaction characteristics and hydraulic conductivity coefficient can provide good predictions. The fine-grained soil can readily be used as a top liner material. In its use as a sanitary landfill bottom liner, soil amendments are needed to improve its swell and shrink characteristics and breakthrough time attribute.

Keywords: Breakthrough Time, Compacted Soil Liner, Hydraulic Conductivity, Landfill Liner, Unconfined Compressive Strength, Volumetric Shrinkage Strain

Abstract Format

html

Language

English

Format

Electronic

Keywords

Sanitary landfills

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Embargo Period

8-7-2024

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