Strength behaviour of Clayey Soil modified with processed periwinkle shell ash

Area of Science:

• Geotechnical Engineering
• Materials Science
• Environmental Engineering

Background:

• Periwinkle shells, generated globally from various sources, pose environmental risks if improperly disposed of.
• Indiscriminate disposal of periwinkle shells can lead to environmental hazards.
• There is a growing need for sustainable alternatives to conventional cement stabilization in civil engineering projects.

Purpose of the Study:

• To investigate the potential of processed periwinkle shell ash (PSSA) as a sustainable material for clay soil stabilization.
• To improve the engineering characteristics of clay soil for enhanced pavement structure preservation.
• To offer an eco-friendly alternative to traditional cement-based stabilization methods.

Main Methods:

• Clay soil samples were collected and subjected to standard laboratory tests, including California Bearing Ratio (CBR), Unconfined Compressive Strength (UCS), durability, sieve analysis, and consistency limits.
• Microstructural analyses using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) were conducted on clay-PSSA admixtures.
• Optimized stabilization was determined at 5.5% PSSA content.

Main Results:

• Stabilization with 5.5% PSSA significantly improved UCS from 392.77 to 460.60 kN/m² and CBR from 32.07% to 61.60% (unsoaked) and 21.00% to 46.81% (soaked).
• Optimum Moisture Content (OMC) increased from 15.36% to 17.02%, and Maximum Dry Density (MDD) increased from 1.61 to 1.88 g/cm³ with increasing PSSA content.
• Microstructural analysis revealed the formation of calcite minerals through carbonation reactions, indicating successful stabilization.

Conclusions:

• Processed periwinkle shell ash is an effective and sustainable material for stabilizing clay soil, yielding optimal results at 5.5% stabilization for road construction.
• Utilizing PSSA reduces environmental pollution associated with shell waste and decreases reliance on cement, promoting economic viability.
• The chemical reactions involving CaCO₃ and Ca(OH)₂ in PSSA contribute to the formation of calcite, enhancing the durability and strength of stabilized clay.