The researchers conducted tests on weak expansive soil to understand its swelling, shrinkage, and permeability characteristics. They found that soil compactness of 95% is best for embankment construction. Lime treatment reduces swelling and shrinkage, with lime-treated soil having only 0.7% total swelling-shrinkage ratio. Permeability decreases with increasing dry density, with lime-treated soil having higher permeability than untreated soil at the same compactness. The study suggests using 95% compactness for weak expansive soil embankments and lime treatment to reduce swelling and shrinkage.