Development of Extrudable High-Strength Fiber-Reinforced Concrete Incorporating Nano-Calcium-Carbonate (2020-09)¶

The use of extrudable (3D printable) concrete in construction has attracted increasing attention, whilst the major obstacles to its wider application lie in the difficulties in materials design, particularly when fibers are added as an alternative to reinforcement. In this study, high strength fiber reinforced concrete (HSFRC) mixtures for extrusion were developed, and the influences of nanoparticles and carbon, steel and glass fibers on their extrudability, buildability and strength properties were investigated. It was found that the addition of nanoparticles and fibers would enhance the rheological properties for shape retention. It was also found that the addition of steel fibers would be more effective in improving the strength but less effective in improving the interlayer bond compared to the addition of carbon or glass fibers, whereas a suitable amount of nanoparticles would generally favor the strength and interlayer bond. Lastly, a conceptual model for the design of extrudable concrete mixtures and some explanations from the perspective of thixotropy were presented. This study shall advance the development of extrudable HSFRC