Reinforcement method for 3D concrete printing using paste-coated bar penetrations

Reinforcement integration is the largest technological challenge in 3D Concrete Printing. Recent studies of inprocess 'bar penetrations' into fresh printed layers shows promise as an interlayer reinforcement. The formation of induced voids around penetrated bars reduces the bond, hindering reinforcing potential. In this study, cement paste-coating bars during penetration is investigated to increase bar bond by void filling. A cement paste is developed with red pigment added allowing visual analysis of paste coverage and embedment. Printed wall sections reinforced with and without paste-coated bars are tested in 3-point bending and compared to casted variants. Results show that paste-coated bars performed significantly better than non-paste coated bars. Strength and ductility are comparable to casted variants thereby concluding the paste-coating method effective. The hypothesis of void filling is validated through analysis of paste embedment which occurred in the top 50% of penetration. Whereas compaction of surrounding concrete occurred in the bottom region.