Alternative reinforcements for digital concrete construction

Abstract

Applications of structural concrete require use of reinforcement in one form or another. The known reinforcement concepts in additive concrete construction typically rely on conventional reinforcement approaches, which provide a solid basis for structural design, since existing guidelines and codes can be used. However, the use of conventional steel reinforcement poses serious limitations to the digitalization and automation of fabrication techniques. The article at hand presents two alternative approaches of reinforcing 3D-printed concrete structures: (1) additive manufacturing of steel reinforcement elements, (2) use of high-performance microfiber to achieve strain-hardening behavior of printed concrete. For both approaches materials and manufacturing techniques are briefly described followed by the results of mechanical testing and complimentary microscopic investigations. The printed steel bars showed similar mechanical performance in comparison to ordinary steel bars of the same cross-section area and comparable bond behavior to concrete too, as observed in pull-out experiments. The addition of 1% to 1.5% high-density polyethylene microfiber to fine-grained matrix enabled for printable strain-hardening cement-based composites (SHCC) with a tensile strain capacity of up to 3.2%.