Development of M-A-S-H binder system with MgO and calcined marine clay

• Main Author: Jeevaganth, Prashin
• Other Authors: Qian Shunzhi
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Civil engineering
• Online Access: https://hdl.handle.net/10356/158945
• Institution: Nanyang Technological University

In a metropolitan city such as Singapore, it is evident that there is a constant and increasing need for infrastructure as the nation and economy continues to develop. The primary component in the construction of these infrastructure is concrete and thus construction being a large industry in Singapore, it is important to consider the environmental impacts of this industry. Till today, the most commonly used component in concrete is Ordinary Portland Cement (OPC) due to its ease of procurement and good performance as a binder. However, the production of OPC results in a large amount of carbon dioxide gas and greenhouse emission into the atmosphere. This contributes to the greenhouse effect and results in rising temperatures and sea levels. These consequences directly affect an island nation such as Singapore. Therefore, it is important that more sustainable methods of construction be explored. MgO-based binder systems are considered alternatives to OPC as it results in less net CO2 emission. MgO-silica fume and MgO-metakaolin binder systems have been developed and could reach comparable compressive strength to that of PC under ambient curing. However, silica fume and MgO-metakaolin are not as abundantly available and easy to procure. Marine clay could be used as a supplementary cementitious material (SCM) instead due to its abundance in various coastal regions. It is also a common waste product in excavations and other construction projects. In this project, the goal is to develop a binder system comprising of MgO and calcined marine clay(CMC) which with comparable mechanical properties as that of OPC. Carbonation curing of the binder system was also investigated considering its effect on strength gain of MgO based binder systems. It was found that the compressive strength of the developed MgO-CMC binder system reached 29.6 MPa after 28 days. In addition, carbonation curing had increased the rate of strength gain of samples as compared to ambient curing significantly. The ultimate strength reached by samples was also higher for carbonation cured samples. The microstructural development was elaborated by X-Ray Diffraction, Thermogravimetric analysis and Nuclear Magnetic Resonance(NMR) Spectroscopy. In addition, a quantitative analysis of carbon sequestration capacity was conducted, reaching 7.6% after 28 days