Abstract
Many recent studies in the development of floating concrete structures focused on a connection system made of modules. In the connection system, the modules are designed to be attached by pre-stressing (PS) while floating on the water, which exposes them to loads on the surface of the water. Therefore, the development of a pre-connection material becomes critical to ensure successful bonding of floating concrete modules. Micro-silica mixed aqua-epoxy (MSAE) was developed for this task. To find the proper MSAE mix proportion, 0% to 4% micro-silica was mixed in a standard mixture of aqua-epoxy for material testing. Also, the effect of micro-silica on the viscosity of the aqua epoxy was evaluated by controlling the epoxy silane at proportions of 0%, ±5%, and ±10%. After completion of the performance tests of the MSAE, we evaluated the effect of MSAE in a connected structure. The plain unreinforced concrete module joint specimens applied with MSAE at thicknesses of 5, 10, and 20 mm were prepared to be tested. Finally, we evaluated the performance of MSAE-applied reinforced concrete (RC) module specimens connected by PS tendons, and these were compared with those of continuous RC and non-MSAE-applied beams. The results showed that the mix of micro-silica in the aqua-epoxy changed the performance of the aqua-epoxy and the mix ratio of 2% micro-silica gave a stable failure behavior. The flexural capacity of concrete blocks bonded with MSAE changed according to the bond thickness and was better than that of concrete blocks bonded with aqua-epoxy without micro-silica. Even though MSAE insignificantly increases the load-carrying capacity of the attached concrete module structure, the stress concentration reduction effect stabilized the failure of the structure.
Highlights
Great efforts to utilize the vast space occupied by the ocean have been attempted in many countries
In this study, we optimized the micro-silica mixed aqua-epoxy (MSAE) formulation and we verified the performance of unreinforced plain concrete and Pre-stressed Concrete (PSC) modules attached using micro-silica aqua-epoxy (MSAE)
1) To estimate the optimum MSAE mix proportion, 1%, 2%, 3%, and 4% of micro-silica were added to aqua-epoxy (AE) and tensile and bond shear tests were performed to evaluate the effects
Summary
Great efforts to utilize the vast space occupied by the ocean have been attempted in many countries. Kim et al [3] verified the performance of structural filler epoxy and primer aqua-epoxy (AE) and tested their connecting performance in concrete members. Woo [4] suggested a method of roughening the surfaces of concrete members before bonding to increase the bonding area of the epoxy-concrete interface. This method was unsuccessful because aqua-epoxy has a high viscosity, which resulted in surface irregularities. A series of micro-silica (SiO2) with high chemical stability was selected for enhancing the performance of the bonding material. Two unreinforced concrete modules with dimensions of 100 mm 100 mm 190 mm were attached using micro-silica aqua-epoxy (MSAE) developed from the selected mix proportion. The beam specimens were tested using a 3-point bending test
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