Effect of Calcium-Based Derivatives on Consolidation, Strength, and Lime-Leachability Behavior of Expansive Soil

The current study aims at examining the effect of different calcium-based stabilizers {calcium hydroxide [Ca(OH)2], calcium carbonate [CaCO3], and calcium chloride [CaCl2]} on the geotechnical properties and lime-leaching behavior of expansive clay. The lime-leaching tests were conducted on clay samples that were compacted at maximum Proctor dry density values relying on specially fabricated molds and subjected to water flow conditions for a specific period (up to 7 days). In order to study the effect of pore fluid on the lime-leachability patterns, the pH of the leaching solution was kept at 7 (pH of deionized double-distilled water) and at 4 (adjusted using 0.1 N HNO3). The effect of curing period (1, 7, 14, and 28 days) on the lime-leaching pattern and unconfined compression strength (UCS) behavior were also studied. One-dimensional fixed-ring consolidation tests were performed to quantify the effect of various stabilizers (at fixed dosage of 4% by weight of dry sample) on the swell and deformation characteristics. The results of the study indicate that with an increase in curing period, irrespective of the type of stabilizer, the calcium concentration in the leachate reduced. The flow duration (7 days was adopted in the study) had an insignificant effect on the resultant lime-leaching values. When acidic water was used as flushing solution, relatively higher concentrations of calcium were noticed, which further establishes the fact that amorphous pozzolanic compounds formed in the early hydration reaction stages are easily soluble. Furthermore, the associated anions in respective stabilizers have a direct bearing on the resultant UCS and consolidation behavior.