Investigating Effects of Phosphorus Ions on Geotechnical Properties of Bentonite

As pore fluid’s chemical properties in cohesive soils may have decisive effects on geotechnical characteristics of barriers, an investigation carried out to study bentonite-contaminant interactions at various phosphorus ion concentrations. Bentonite specimens were artificially contaminated by mixing the soil with di-ammonium phosphate (DAP) in concentrations ranging from 0.01 to 0.1mole/l. The conventional geotechnical experiments such as compaction, unconfined compressive strength, and direct shear box were performed. Findings on phosphorus ion impact on the water content (ω) change, dry density, unconfined compressive strength, internal friction angle, and cohesion indicate that: Increasing phosphate ion concentration in soil-electrolyte may lead to an increase in cohesion, and unconfined compressive strength of contaminated bentonite. The obtained results showed that 57% and 29% improvement in cohesion and unconfined compressive strength, respectively may be achieved by maintaining a high DAP concentration of about (0.1 mol/l). Our observations showed that a given value of 23% optimum water content with deionized water increased to 25% at the highest phosphorus ion concentration.

کلیدواژه ها:

Bentonite ، Phosphorus ion ، mechanical properties ، Di-ammonium phosphate