GEOTECHNICAL PROPERTIES OF LIQUID POLYMER AMENDED FINE-GRAINED SOILS

Author

Basanta Dhakal, Southern Illinois University CarbondaleFollow

Date of Award

8-1-2016

Degree Name

Master of Science

Department

Civil Engineering

First Advisor

Kolay, Prabir

Abstract

The present study investigates the effect of liquid polymer on the geotechnical properties as well as the microstructure of fine-grained soil. Commercially available liquid polymer (Acrylic Polymer, MA-60) is used to stabilize commercially available EPK Clay soil and Carbondale soil. Physical properties test was performed which includes Atterberg limits test, linear shrinkage test, hydrometer analysis, and specific gravity test. Standard Proctor test was performed to determine the relationship between dry unit weight and moisture content of the soil samples. The polymer is mixed at various percentages (i.e., 2, 3, 4, and 5%) of the dry weight of soil. Tap water is added corresponding to its OMC (Optimum Moisture Content) for a particular soil-polymer mixture and compacted to achieve its maximum dry unit weight. The compacted samples were allowed to cure for 7, 14, and 28 days under confined and open air environment. Unconfined Compressive Strength (UCS) test was performed to evaluate the strength of polymer stabilized soil. The results show that with the addition of polymer; UCS value for EPK Clay samples prepared at OMC (i.e., 32.50%) increases from 30-75% in open air environment and the UCS value increases from 12-14% in confined air environment. Carbondale soil samples prepared at OMC (i.e., 23.50%) shows cracks while curing in open air environment and there is no significant change (i.e., 1.2- 13.8%) of strength in confined air environment. For the Carbondale soil samples prepared with reduced moisture contents (less than OMC i.e., 12.50%) and cured in open air environment shows increase in UCS strength from 7-10%. California Bearing Ratio (CBR) test was performed for EPK Clay and Carbondale soil and there was marginal increase (i.e., 14%) in CBR value for Carbondale soil but a significant increase (i.e., 340%) in CBR value for EPK Clay. X-Ray Diffraction (XRD) test was conducted for EPK Clay and Carbondale soil to determine the mineralogical composition of original and liquid polymer stabilized soil. It was observed that, no new minerals were formed with the addition of polymer. Scanning Electron Microscope (SEM) test was conducted to analyze the microstructure of original and liquid polymer stabilized soil. It was observed that for EPK Clay, polymer resulted in more compact microstructure. However, there was no significant change in the microstructure of Carbondale soil with the addition of liquid polymer.