| Summary: | 博士 === 國立臺灣海洋大學 === 河海工程學系 === 103 === A solar panel, also known as photovoltaic (PV) panel, recycling process should be attempted on the solar cells, comprised primarily of silicon, silver and aluminum. The process usually requires the solar cells to be ground into chips, flakes or powders, which can be utilized in the production of products like concrete. Therefore, the main purpose of this study is to investigate the use of ground solar cells for the cement-based composite and its corresponding process of hydration. The steps of investigation are threefold as follows. Firstly, the study observed the grounded powders by using x-ray fluorescence method (XRF) and toxic characteristic leaching procedure (TCLP) to realize all the possible components to the possible replacement of cement. Secondly, the research employed the grey Taguchi method and multi-quality characteristics to identify the key factors for mechanical properties of concrete substrates with the grounded powder thru various experiments, including compressive strength test, resistivity test, water absorption and permeability test. Thirdly, the identified key factors were referred to reproduce a new set of glass-powder (GP) concrete specimens, so as to study on their mechanical properties, durability and micro-mechanism, and then lead it to clearly identify its process of hydration and application with the PV powder.
The conclusions are summarized as (1)The XRF test identified the main components of the PV powder as SiO2, Na2O and CaO, which may potentially be used as the pozzolanic admixtures to concrete. (2)Thru the grey Taguchi method, responses to the factors were then analyzed to conclude as twofold. Firstly, the water-binder (W/B) ratio of concrete was the most important factor due to its maximum contribution to the response for the factor of the W/B ratio. Secondly, the alkali solution and PV powder substitute for cement played the next two important roles. The best performance came from the absence of the alkali solution with 5% of PV powder substitute for cement, explained as the self-pozzolanic capability of the PV powder including SiO2, CaO and Al2O3, which of all are the main roles of a pozzolanic reaction. Besides, the high substitute of cement made the less factorial response, i.e. the obvious evidence of the limited use of the PV powder in concrete for substitute of cement. (3)The 56-day performance of one with 5% of PV powder substitute for cement was better than the one without that (namely, the control group). The reason behind that may be due to the pozzolanic reaction caused by the PV powder substitute for cement making more closely compacted in substances. As observed in MIP test, the pores are characterized as C-S-H gel pores and capillary pores depending on the pore sizes found in MIP, and both values of porosity were smaller other than the control group, in which the case of capillary pores was more specific than the other one. Furthermore, thru SEM, the formation of C-S-H and C-A-S-H gels was found to in pores to cause more closely compacted in substances as evidence to the promotion of the compressive strength. However, the presence of alkali solution, either KOH or NaOH+Na2CO3, did not provide any promotion to the GP concrete thru all experiments.
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