Mixed material from landfill as caisson infill

• Main Author: Tan, Qian Ying
• Other Authors: En-Hua Yang
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering
• Online Access: https://hdl.handle.net/10356/177608
• Institution: Nanyang Technological University

This study is conducted to investigate the possibility of utilizing mixed material obtained from Semakau Landfill as reinforced caisson infill. The focus of this study is to observe the length change and deterioration of mortar specimen when subjected to sulfate attack. The mortar specimens were prepared according to ASTM C-109. There was a total of 4 experiments conducted for this study. Experiment 1 is about immersing prism specimens of wall and base of caisson structure into 0.5%, 1.5%, 3% and 5% of sodium sulfate solution for 133 days to observe the length change in immersed specimens and to obtain the percentage change in length of mortar specimen which was recorded every 7 days. The results indicate that the rate of expansion of specimens increases as the concentration of sodium sulfate solution increase. Significant deterioration and cracks were found on the surface of wall specimens immersed in 5% sodium sulfate solution was observed at day 133. No deterioration observed on specimens immersed in 0.5%, 1.5% and 3% sodium sulfate solution. Experiment 2 uses high temperature to increase the deterioration rate of mortar specimens by immersing wall and base prism mortar specimens into 5% of 40 °C and 50 °C of sodium sulfate solution for 63 days to also observe the length changes of specimen to obtain percentage change in length of mortar specimen and was recorded after every 7 days. The results indicated that the rate of expansion of specimens increases as the temperature of sodium sulfate solution increases. There was not deterioration observed on specimens at day 63. Experiment 3 is to observe the length changes and to obtain the percentage of length changes in prism specimens every 7 days by immersing in 1% and 3% of magnesium sulfate solution for 56 days. The percentage change in length for specimen immersed in 3% of magnesium sulfate solution is higher than specimen immersed in 1% of magnesium sulfate solution therefore indicating that the rate of expansion of specimens increases as the concentration of magnesium sulfate solution increases. There were no signs of deterioration observed on specimens at day 56. Experiment 4 is about observing the mass change of mortar cubes specimens by immersing in synthetic leaching solutions of seawater (SW), mixed material leachate (MML) and high concentrations mixed material leachate (HMML) for 63 days to study the interactions between these solutions and caisson structure. Mass was recorded every 7 days. The results indicated that the mass change ratio of specimens increases when the concentration of synthetic leaching solution increases. There are signs of deterioration observed on specimens immersed in HMML at day 63.