Matric suction of compacted soils

• Main Author: Ng, Teik Ting
• Other Authors: Leong Eng Choon
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/67410
• Institution: Nanyang Technological University

This project covers the direct and indirect measurement of matric suction of compacted soil. The soil used in this project was Bukit Timah Granite residual soil. Residual soil was compacted with standard Proctor and modified Proctor effort. Matric suction measurements were conducted on the compacted soil specimens using the high capacity tensiometer (HCT), null-type axis-translation technique and chilled-mirror dew point device. Matric suction measured from three different methods showed a steady trend, which matric suction decreased with the compacted water content. However, the HCT and null-type axis-translation method were unable to measure high suction whereas low accuracy on total suction measurement was encountered by chilled-mirror dew point device on low suction. Correction of water activity measured was applied for measurement on low suction to resolve this problem. Equilibration time of the HCT increased with matric suction of the soil specimen whereas equilibration time of null-type axis-translation technique was independent of both air pressure applied and matric suction of the soil specimen. However, cavitation occurred during matric suction measurement of the HCT for suction more than 1200 kPa. Air diffusion into the water reservoir of null-type axis-translation setup caused the matric suction to be underestimated. High sensitivity of the chilled-mirror dew point device leads to high fluctuation between first round and second round of the total suction measurements. Matric suction values collected from several papers were compared to evaluate the relationship between matric suction and liquid limit of the soil.