Experimental comparative research
Unconfined comprehensive strength
California bearing ratio test

Includes bibliographical references

This experimental study investigated the potential of eggshell powder (ESP) as a sustainable bio-based stabilizer for improving the engineering properties of Guadalupe Clay in Imus, Cavite. The natural soil was classified through Atterberg Limits testing as a high-plasticity clay with a Plasticity Index (PI) of 49.49%, indicating very high swell potential and poor suitability for construction applications. Laboratory tests, including Standard Proctor Compaction, Unconfined Compressive Strength (UCS), and California Bearing Ratio (CBR), were conducted to evaluate the effects of varying ESP contents (5%, 7.5%, and 10%) on soil behavior. Results showed that ESP significantly influenced soil compaction, strength, and volume stability. The highest Maximum Dry Density (MDD) of 13.41 kN/m³ was achieved at 10% ESP, corresponding to a 14.1% increase compared to untreated soil, while the PI was reduced to 21.57%, indicating improved workability. However, the optimum mechanical strength was observed at 7.5% ESP, which produced the highest UCS of 1350 kPa, representing a 6.3% increase over the control specimen. In contrast, soaked CBR values decreased with increasing ESP content, from 4.7% in untreated soil to 1.8% at 10% ESP. Despite this reduction, swelling behavior was significantly improved, with maximum swell reduced from 0.4% to 0.1% or lower. Overall, the findings demonstrate that ESP is an effective, low-cost, and environmentally sustainable stabilizer that enhances particle packing and significantly reduces the expansive behavior of clay soils, supporting its potential application in sustainable geotechnical and pavement engineering.