Performance of lime kiln dust-treated subgrade soils

Lime kiln dust (LKD), which is a byproduct of lime production, has been increasingly used as an additive to improve the workability of clayey soils. However, limited research has been conducted to quantify the benefits of LKD used for this purpose. In this study, laboratory experiments were conducted to quantify the benefits of LKD for stabilization of subgrade soils. Two types of clayey soil from two different sites were selected and mixed with different percentages of LKD. The Atterberg limits, moisture-density relationships, swelling potential, durability, and unconfined compression strength of the native and LKD-treated soils were determined. The strength gain with time was also studied to assess the benefits of curing (if any). The LKD-treated samples were compacted and cured for 1-2 hours and 1, 3, 7, and 28-day periods, and then tested to determine the unconfined compressive strength and volume expansion. A strength gain of more than 100% for the LKD-treated soil over the untreated soil was observed. The results also indicated that the strength of LKD-treated soil continuously increased with time. LKD also substantially reduced the plasticity and swelling potential of subgrade and improved the workability and durability of clayey soil. In general, LKD performed well and can be used for modifying and/or stabilization of clayey soil subgrades.