Effects of Some Metal Sulfates on the Strength and Swelling Properties of Lime-Stabilised Kaolinite

Abstract

The presence of sulfates during lime-stabilisation of clay soils may modify the clay–lime reaction products with undesirable consequences such as excessive expansion and reduced strength. Some failures in major highways have been attributed to formation of these expansive products. Sulfates may occur in the parent stabilisation material or in the ground water either naturally, or artificially due to industrial or non-industrial human activity. This paper reports the effects of varying sulfate type and concentration on the development of compres-sive strength and on the expansion behaviour of a lime-stabilised commercial kaolinitic clay, when sulfates of calcium, magnesium, sodium and potassium are artificially introduced into the clay. The results clearly illustrate that the sulfate cation type is a major factor in influencing subsequent behaviour and performance of the clay. The effects of the sulfates of sodium, magnesium and potassium are found to be different from and more deleterious than those of calcium.

Keywords:

• Clay soils
• compressive strength
• lime
• soil stabilisation
• sulfates
• swelling