Study on behaviour of soil with phosphogypsum as stabiliser

Abstract

Background/Objective: Civil engineering structure resting on expansive soils needs more attention since it causes undesirable engineering behavior when the soil comes in contact with water. The areas consisting of expansive soil need a proper stabilization method to solve the site problems faced by the civil engineers. Pavements constructed on such soil shows signs of damage continuously during the service life of the pavement eventually increase the maintenance costs. Stabilization of these soils is a usual practice for improving the strength. Methods: In this work an attempt was made on the utilization of Phospho Gypsum (PG) with soil by adding various percentages of 2, 4, and 6% in soils and accessed their geotechnical behaviour for different curing periods. The effects of PG treatment on the microstructure and strength improvement of compacted expansive clays are studied based on Microstuctural analysis and Unconfined Compression tests for different curing periods of 0, 14 and 28 days. Findings: UCS performed on these mixes and identified that addition of phosphogypsum attained high strength with the increasing percent of phosphogypsum in soils. From the test results, it was observed that the UCS peak stresses were increases to 162kPa and 336kPa from 75 kPa and 122 kPa for soil samples S1 and S2 at 28days of curing. X-ray Diffraction and Scanning Electron Microscopy were carried out for microlevel analysis and the results confirmed the presence of minerals and cementation nature in the treated soil. Improvement: From the experimental study, it is observed that the treatment of the expansive soil with the addition of Industrial waste material Phosphogypsum is more efficient in subgrade modification and other geotechnical applications.