Hyeongi Lee

The use of supplementary cementitious materials is customary in contemporary concretes. Different industrial by-products and waste materials have been investigated earlier for such applications. In this paper, the use of organic light-emitting diode glass (OLED) display waste as a partial replacement of cement binder in concretes has been explored. Concretes with 10%, 20%, and 30% substitution (by weight) of ordinary Portland cement (OPC) by OLED powder were developed, and the resulting mechanical properties and durability characteristics were evaluated. The results showed that OLED addition leads to strength improvement of up to 8% after 28-day age. Also, the resistance to chloride-ion penetration and sulfate attack improved considerably. The chloride binding capacity for the developed concretes was also investigated. It was demonstrated that the OLED powder incorporation is beneficial in improving the corrosion resistance of the modified concrete. The enhanced mechanical and durability properties of modified concrete point toward the excellent performance of OLED-incorporated concrete for improved service life. Incorporating OLED display waste in concrete as a partial cement replacement can also reduce environmental burden and concrete cost.

In this study, we report on the development and testing of hydrophobic coatings using cellulose fibers. The developed hydrophobic coating agent secured hydrophobic performance over 120°. In addition, a pencil hardness test, rapid chloride ion penetration test, and carbonation test were conducted, and it was confirmed that concrete durability could be improved. We believe that this study will promote the research and development of hydrophobic coatings in the future.

The use of pozzolanic waste materials as partial cement replacement is customary in contemporary concretes from the sustainability perspective. In this study, glass wastes from organic light-emitting diode (OLED) and liquid crystal display (LCD) were used waste as supplementary cementing material (SCM) in concrete. For the first time, detailed microstructural and hydration attributes have been studied for such blended concretes. Concretes with 10%, 20%, and 30% substitution of ordinary Portland cement (OPC) by OLED and LCD glass powders were developed. The resulting mechanical properties, hydration attributes, and microstructural features were studied at various ages, up to one year. Superior mechanical properties were shown after 28-day age for blended concretes; however, much profound improvement in compressive and flexural strength was observed at 1-year age. The enhanced mechanical properties of modified concretes are attributed to greater pozzolanic activity and secondary hydrates formation of OLED and LCD glass powders in alkaline cementitious matrix. Greater C-S-H gel formation, lower permeability, and more refined microstructure of the blended concrete were corroborated by thermogravimetric analysis (TGA), Rietveld quantitative phase analysis (RQPA), backscattered electron image analysis (BSE), and mercury intrusion porosimetry (MIP). 20 wt% has been found as the optimal value of cement replacement by either LCD or OLED powder. The results clearly indicate LCD and OLED can be successfully used as SCM for developing concrete with improved properties.