Compacted clay-sand mixtures/sand-bentonite mixtures, when installed as landfill liners are subjected to saline intrusions due to the inorganic dissolved salts present in the leachate. Saline intrusions play a vital role in the desiccation crack formation in compacted soil liners along with gradation and initial compaction conditions when subjected to multiple wet-dry (W-D) cycles. In this research, expansive clay and the three clay-sand mixtures, featuring low (32%), medium (50%) and high (68%) sand contents, were utilized to prepare compacted specimens under Modified (MOD) Proctor conditions. Cyclic W-D tests were carried out on these specimens with distilled water (DW) and salt solutions (0.4 M NaCl, 0.4 M CaCl2 and 0.4 M AlCl3 solutions) as inundating fluids. Digital images of specimens were captured after the first, second and fifth drying cycles and analyzed using ImageJ Fiji software. The study reveals that the area of desiccation cracks decreases with an increase in the cation valence of the salt solution during W-D cycles. Higher osmotic suction and particle aggregation induced by salt solutions result in increased total suction and tensile strength, thus reducing the area of desiccation cracks. With the increase in the number of W-D cycles, the specimen with lower sand content became more susceptible to desiccation cracks, whereas the specimens with medium and higher sand content did not showcase any significant desiccation cracking even after multiple W-D cycles. The combined effect of the increase in sand content and salt intrusions reduced the area of desiccation cracks in specimens prepared using expansive clay and clay-sand mixtures.

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Investigating the Impact of Saline Intrusions on Desiccation Cracks in Compacted Clay-Sand Mixtures During Wet-Dry Cycles

  • Sabari Ramesh,
  • T. Thyagaraj

摘要

Compacted clay-sand mixtures/sand-bentonite mixtures, when installed as landfill liners are subjected to saline intrusions due to the inorganic dissolved salts present in the leachate. Saline intrusions play a vital role in the desiccation crack formation in compacted soil liners along with gradation and initial compaction conditions when subjected to multiple wet-dry (W-D) cycles. In this research, expansive clay and the three clay-sand mixtures, featuring low (32%), medium (50%) and high (68%) sand contents, were utilized to prepare compacted specimens under Modified (MOD) Proctor conditions. Cyclic W-D tests were carried out on these specimens with distilled water (DW) and salt solutions (0.4 M NaCl, 0.4 M CaCl2 and 0.4 M AlCl3 solutions) as inundating fluids. Digital images of specimens were captured after the first, second and fifth drying cycles and analyzed using ImageJ Fiji software. The study reveals that the area of desiccation cracks decreases with an increase in the cation valence of the salt solution during W-D cycles. Higher osmotic suction and particle aggregation induced by salt solutions result in increased total suction and tensile strength, thus reducing the area of desiccation cracks. With the increase in the number of W-D cycles, the specimen with lower sand content became more susceptible to desiccation cracks, whereas the specimens with medium and higher sand content did not showcase any significant desiccation cracking even after multiple W-D cycles. The combined effect of the increase in sand content and salt intrusions reduced the area of desiccation cracks in specimens prepared using expansive clay and clay-sand mixtures.