Optimization of material for 3D concrete printing with recycled glass

• Main Author: Hwang, Benjamin Soon Yew
• Other Authors: Tan Ming Jen
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Mechanical engineering; Engineering::Civil engineering::Construction technology
• Online Access: https://hdl.handle.net/10356/140922
• Institution: Nanyang Technological University

3D Printing is steadily gaining popularity around the world for its ability to manufacture objects of complex geometry with minimal wastage. While it is gaining popularity for use in many industries such as in medicine, electronics, and fashion, it has not seen much use in the building and construction industry on a large commercial scale. 3D Printing, particularly for the deposition of concrete, presents a host of unique challenges due to the nature of cement itself. Cement behaves as a non-newtonian, visco-plastic Bingham material which viscoelastic properties changes with respect to time. Hence, it is crucial to ensure that the concrete stays flowable for printing before deposition, yet at the same time, maintain strength for building up layers after deposition. This paper seeks to explore the use of recycled glass in substituting river sand as an aggregate in structural concrete. Experiments such as rheological tests, material characterization tests and mechanical tests will be conducted in 20% increments of sand replacement levels to investigate the behavior of recycled glass in concrete. Apart from experimenting with the sand-glass ratio, chemical additives such as nano-clay will also be used. In addition, recommendations for future research is also discussed. The following key observations were noted in comparing the use of recycled glass aggregates (RG) against river sand in 3D printed concrete: 1. There was a decrease in buildability (42%), compressive strength (27%), and interlayer bonding strength (60%) 2. The inclusion of nano-clay significantly improved the buildability of RG mixes (125%) 3. RG concrete specimens have exceeded the permissible limit of 0.10% ASR expansion by day 14 (0.13%)