Investigating the Effect of Eggshell Ash and Crushed Stone Powder on Geotechnical Properties of Expansive Soils: In Case of Dukem Town

Abstract

Expansive Soils Are Those Having The Ability To Undergo Excess Swelling-Shrinkage Behavior Due To Available Smectite Mineral In Soil Mass And Which Causes Distress On Overlaid Structures As Moisture Content Varies. This Soil Type Covers More Than 40% Of Land Area In Ethiopia, And Currently It Becomes An Alarming Issue Throughout The Overall World. So, To Overcome Such Problems This Study Was Tried To Apply Ground Improvement By Using Different Stabilizing Agent slike Eggshell Ash (ESA) And Crushed Stone Powder (CSP) Which Are Selected Based On Their Cost Effectiveness, Availability, Pollutant Reducibility And Environmental Compatibility. For This Study expansive Soil Samples From Three Different Test Pits Were Collected To Be Categorized And Identified As The Weakest Based On Their Plasticity Property, Gradation, Swelling Property And Compressive Strength And Further The Weakest Soil, Selected Additives And Soil-Additive Mixtures Were Characterized For Their Mineralogical Compositions Using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM) And X-Ray Diffraction(XRD) Analysis. This Paper Also Presents The Results Of Some Index And Engineering Properties including Atterberg Limits, Compaction, Free Swelling, And Unconfined Compressive Strength Of Expansive Soil Mixed With The ESA At 2%, 4%, 6%, And 8% By Dry Weight Of Soil. The Result shows That The Decrease In Liquid Limit (84.38% To78.23%), Plasticity Index (47.16% To 32.65%), Maximum Dry Density (1.32g/Cm3 To 1.29g/Cm3), Free Swelling Index (95% To 36.36%), Free Swell ratio (1.95 To 1.36), And Linear Shrinkage (21.96% To 18.87%) With The Addition Of ESA Up To 8%. Whereas, Increase In Optimum Moisture Content (35.78% To 36.36%), Plastic Limit (37.22% To 45.58%), And UCS From 94.74kpa To 149.17kpa (Uncured) And 177.68kpa (Cured) Were Observed For Addition Of ESA To Soil Sample. And Also 6% ESA Was Combined With CSP At 5%, 10%, 15% And 20% By Dry Weight Of Soil To Investigate Their Effect On Properties Of Natural Soil. Again, The Result Shows Better Improvement Of Soil Properties By Reducing Plasticity Property, Shrinkage Capacity, Optimum Moisture Content, Swelling Characteristics, And Degree Of Compressibility And Increasing Rate Of Consolidation, Maximum Dry Density, And Compressive Strength Of Natural Soil. Results Also Shows That Curing Have Positive Impact On Improvement Of Expansive Soil Related To Strength. Based On The Overall Test Results, The Optimum Ratio Of ESA And CSP For The Improvement Of Expansive Soil In This Study Was Proposed As 6% And 15% Respectively