Experimental Study on the Effect of Thermal Treatment on the Water Stability of Compacted Loess

In this study, the water stability of compacted Yangling loess after thermal treatment was analyzed in detail. After heat treatment at temperatures of 400°C or less, Yangling loess disintegrates in water; thus, disintegration tests were performed to clarify the amount and timing of disintegration for different temperatures (100–400°C) and degrees of compaction (84%–100%). After heat treatment at temperatures equal to or above 500°C, Yangling loess did not disintegrate in water; thus, the water stability coefficient (the ratio of wet to dry strength) was used for quantitative description of the water stability of thermally treated soil. Measurements of the water stability coefficient for different treatment temperatures (500–900°C) and different degrees of compaction (84%–100%) were obtained by unconfined compressive strength tests. The water stability of Yangling loess was greatly affected by both temperature and degree of compaction. For the same degree of compaction, the disintegration time increased and the amount of disintegration decreased with increasing treatment temperature. For treatment temperatures of 400°C or less, the disintegration time increased and the amount of disintegration decreased with increasing compaction at the same treatment temperature. For a given degree of compaction, the water stability coefficient increased with rising treatment temperature, and changed only slightly with increasing compaction for a given treatment temperature for temperatures of 500°C or more.