Experimental Investigation on Inner- and Inter-Strip Reinforcements for 3D Printed Concrete via Automatic Staple Inserting Technique

Abstract

Lack of reinforcements is an existing drawback of 3D printed cementitious components, which is an urgent concern. A staple-inserting apparatus was developed and installed on a 3D printer and automatically fabricated 3D printed and staple-reinforced components with 98% successful insertion to achieve inner- and inter-reinforcement of the printed strips. The inserted staples inside the printed strips improved the compressive strength by 25% maximum owing to the inner locking effect by the staple pins, while the flexural strength did not increase because the scattered staples functioned separately. The staples over the strip interfaces remarkably increased the flexural stress by 46–120%. The inserted staples demonstrated a significant strip locking effect, but the unavoidable voids decreased the bonding between staples and the composite. The mechanical analysis concluded that the printing parameters considerably affected the reinforcing rate. The staple inserting technique proved the feasibility of automatic fabrication of fiber-reinforced and printed concrete structures.

3D Printing Devices and Reinforcing Techniques for Extruded Cement-Based Materials: A Review

“…steel fibers [126], steel rebars [123,124], nails [50], U-nail [129,131] Placing between the layers horizontal a. reinforces the layers only, b.…”

Sewing Concrete Device—Combining In-Line Rheology Control and Reinforcement System for 3D Concrete Printing

“…In this regard, three categories of reinforcing method can be distinguished: the first consists in entraining the reinforcements in the concrete flow simultaneously to the printing [ 11 ] (embedded reinforcements, like fibers and cables can be included in this classification); the second consists in placing the reinforcement before the concrete printing [ 12 , 13 ]; and the third and last method aims to reinforce already deposited layers of concrete by inserting or screwing reinforcements (nails, staples, screws, rebars, etc.) in different directions [ 14 , 15 , 16 , 17 , 18 ]. However, this last reinforcing method needs the implementation of multiple robots or tools (for instance one robot for concrete printing and one robot for reinforcement) and leads to complexity in robotic control and programming [ 19 , 20 ].…”