A comparative study of hardened-state mechanical properties of 3D printed and conventionally cast Fibre Reinforced Concrete

Fiber Reinforcement in additively manufactured concrete is an effective reinforcement strategy and a segue to the use of highly durable Ultra High-Performance Concretes in digital manufacturing. The study of the hardened state mechanical properties such as compressive and flexural strengths of 3D printed elements is an important step towards standardizing the design of 3D printed fiber reinforced elements. In this study, extrusion-based printing techniques are used to manufacture cementitious mor-tar specimen with comparable lengths and depths. Highly cohesive cement with high Sulfoaluminate content and Basalt fibers have been used in the printing of the cementitious mortar specimens. Com-parative analysis of 3-point bending test results of specimen cut from these printed elements and con-ventionally cast specimen of similar dimensions has been performed in this paper. The comparisons have been done by analysing the work of fracture required per unit crack-width for various kinds of specimen. Specimen of l/h ratios of 2, 3, 4 and 5 are examined. Influence of varying depths and number of layers has also been studied. Influence of layer-orientation has been investigated studied to under-stand the interface between hardened layers better. Finally, the effect of compaction of bottom layers under self-weight during printing has been assessed by comparing the performance of specimen cut from the bottom and top of the printed elements.