Soil stabilisation using novel binders

• Main Author: Wong, Geraldine
• Other Authors: Yi Yaolin
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering::Civil engineering
• Online Access: https://hdl.handle.net/10356/173225
• Institution: Nanyang Technological University

In recent years, Singapore has been grappling with a growing issue of construction waste, with a significant portion stemming from marine clay, which consistently contributes approximately more than 10 million tonnes to the local waste stream annually. Concurrently, the depletion of natural resources has added to the concerns. Given the strong demand for sand in construction and land reclamation projects, the scarcity of these natural resources in Singapore has become a cause for worry. Consequently, there is a concerted effort to explore alternative sustainable materials and the recycling of locally available waste materials as part of a broader initiative to establish a circular economy. A common approach involves harnessing and stabilizing soft clay, like marine clay, to serve as a substitute for sand while ensuring the practical usage in construction project. Pumpable filling is used in the research of this project to curb the issue of cohesiveness in marine clay when combined with water. Thus high water content combined with two different GGBS content activated with different CS content had been used. While Ordinary Portland Cement (OPC) has proven effective as an additive for stabilizing, modifying, and enhancing the engineering properties of soil, its production is energy-intensive and leads to significant emissions of carbon dioxide and other pollutants. To provide an alternative solution, this research investigates the feasibility of introducing a modest amount of Carbide Slag with Ground Granulated Blast Slag(CS-GGBS) into the soft clay. In this study, varying proportions of OPC and CS-GGBS are incorporated into marine clay samples, which are then subjected to curing periods of 7, 28 and 56 days. A comprehensive series of tests is conducted to assess the performance and effectiveness of GGBS with CS addition, including the evaluation of Unconfined Compression Strength (UCS), water content, bulk density, flow value, pH and dry density. Additionally, further tests, such as X-ray Diffraction (XRD) and Scanning Electro Microscopy (SEM) are employed to further investigate the morphological characteristics and phase composition of the treated clay slurry. The findings demonstrate that the addition of CS-GGBS effectively increases the workability of marine while utilise low amount of binder content. The optimal CS-GGBS dosage is determined to be 16 kg/m3 to 20 kg/m3 of CS with 60 kg/m3 of GGBS, resulting in the highest UCS at lower OPC content. The mineralogy and microstructure analysis reveals a greater formation of hydration products with increased CS-GGBS dosage and longer curing periods.