UROP Proceedings 2022-23

School of Engineering Department of Civil and Environmental Engineering 82 Department of Civil and Environmental Engineering Micro-tomography and Tensile Testing of Strain Hardening Cementitious Composites (SHCC) to Understand the Microstructure-properties Relation Supervisor: LEUNG, Christopher Kin Ying / CIVL Student: WIJAYA, Fiona Angelica / CIVL Course: UROP1100, Spring Engineered Cementitious Composites (ECC), also called Strain Hardening Cementitious Composites (SHCCs), are innovative construction materials with high tensile ductility and controlled crack width, achieved through the proper incorporation of reinforcing fibers guided by micromechanics. To improve their usage in various structural applications, a better understanding of the microstructure-properties relationship is needed. In this study, micro-tomography and tensile testing were used to investigate this relationship. To enhance the microscopic understanding, fluorescence images of the specimens were taken after the tensile testing, and X-ray tomography photographs were cross-sectionally analyzed to establish a quantitative analysis for linking fiber and pores size distribution with tensile performance. A Cement-free Novel Concrete that Absorbs Greenhouse Gas CO2 to Heal itself and Improve its Mechanical Performance Supervisor: QIU, Jishen/ CIVL Student: MAK, Cheuk Yiu / CIGBM Course: UROP1100, Fall Concrete produced with Mg(OH)2 cement gain strength through carbonation, however, carbonation is a slow processes which could take years owing to the dense microstructure of concrete. To ensure that the early strength of Mg(OH)2 concrete is sufficient to be demoulded, carbonation has to be accelerated. This study investigates the use of Mg(CH3COO)2 to increase the initial rate of formation of hydrated magnesium carbonates (HMCs) by providing extra Mg2+ ions. Sisal fiber which has previously been proven to be conducive to CO2 diffusion was also used in this study to facilitate CO2 penetration. The use of Mg(CH3COO)2 effectively speed up the initial and intermediate strength gain of concrete, doubling the compressive strengths of concrete after 3 days of carbonation.