School of Engineering Department of Civil and Environmental Engineering 74 Department of Civil and Environmental Engineering Biomimicry: Structural Design Lessons from Trees Supervisor: DIMITRAKOPOULOS Ilias / CIVL Student: DOAN Phuc Nghia / CIVL Course: UROP 1000, Summer The study aims to elucidate the relationship between tree geometry and dynamic properties (modal periods and damping ratios). Previous research showed a large discrepancy between modal periods estimated by Finite Element Method and those measured by LiDAR sensor. These discrepancies were attributed to unreliable estimations of the modulus of elasticity (MOE) due to outdated data and neglecting branch mass. However, this study offers an alternative explanation by measuring the exact palm tree’s MOE with a multibeam LiDAR sensor and total mass of branches. The findings show that branch mass accounts for only 30% of the total tree mass, which is unlikely to explain the underestimation of modal periods with less than 6 times. Therefore, the only possible factor might be their overestimated MOE, which was previously overestimated. A Cement-free Novel Concrete That Absorbs Greenhouse Gas CO2 to Heal Itself and Improve Its Mechanical Performance Supervisor: QIU Jishen / CIVL Student: LEE Natalyn Ning Ern / CIVL Course: UROP 1100, Spring Carbon dioxide makes up more than 70% of greenhouse gases; and the production of ordinary Portland cement (OPC), the key ingredient of concrete, is one of the main causes for anthropogenic CO2 emission. In this project, we will be studying a new MgO-based composite developed in our lab. This reactive magnesium oxide cement (RMC) has the potential to be a cleaner concrete– and thus the overall research objective is to enhance RMC self-healing and strength properties. The mechanisms for these properties are related to MgO’s role as a binder and products formed during its carbon sequestration phase. During this term, my short-term research goal was isolating the early hydration characteristics of MgO since it serves as a bottleneck for further hydration and carbonation. This was done by observing material properties with variation of water to concrete ratio, addition of water reducer, and addition of fibre.
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