Screwed Reinforcing Bars in 3D Printed Concrete Walls
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Solution Overview
Problem
Existing methods for producing concrete walls using 3D printing face challenges in introducing vertical reinforcement without complicating the print head design, limiting reinforcement height, and requiring complex structures to accommodate reinforcement mats, which also increases the number of lap joints and manufacturing errors.
Innovation Solution
The method involves screwing reinforcing bars into the concrete wall after partial solidification of layers, allowing for longer bars with fewer connections and enabling automated, economic production by using a screw thread on the rebar and a screw tip for easy insertion, reducing the force required and minimizing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcement mats are used in 3D printed concrete walls, then vertical reinforcement is achieved, but the print head design becomes complex and reinforcement height is limited
Solution Approach 1:
The reinforcement is segmented into individual rebars rather than using continuous reinforcement mats. Each rebar is inserted separately through the printed layers, allowing the print head to maintain a simple single-nozzle design while still achieving vertical reinforcement throughout the wall structure
Solution Approach 2:
The rebars are preliminarily positioned by being inserted into the concrete layers during the printing process itself, rather than requiring complex pre-assembled reinforcement mats. This preliminary insertion action simplifies the print head design while ensuring proper reinforcement placement
2Reliability
If reinforcement bars are inserted immediately after layer application, then reinforcement is secured, but the number of lap joints increases
Solution Approach 1:
Multiple concrete layers are printed in advance before rebar insertion begins. This preliminary layering action creates a solid matrix that can accommodate longer rebars, reducing the number of lap joints needed while maintaining reinforcement reliability
Solution Approach 2:
The insertion timing parameter is changed from immediate insertion after each layer to delayed insertion after multiple layers are printed. This parameter change allows for longer rebar lengths and fewer connections, improving productivity while maintaining structural reliability
3Strength
If reinforcing bars are screwed into fully solidified concrete, then structural integrity is maintained, but the force required for insertion becomes excessive
Solution Approach 1:
The concrete layers are allowed to preliminarily solidify to a semi-hard state before rebar insertion. This preliminary solidification maintains structural integrity while creating a matrix that is still sufficiently workable to accept rebars with moderate insertion forces
Solution Approach 2:
The concrete solidification parameter is changed from fully solidified to partially solidified at the time of rebar insertion. This parameter optimization reduces the insertion force required while maintaining adequate structural integrity for the application
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the reinforcement process, reduces the number of reinforcing bars needed, minimizes lap joints, and allows for fully automated, economic production of high walls with efficient force transfer between the rebar and concrete, while avoiding manufacturing errors.
Implementation Method 1
The reinforcing bar is screwed into the layers before the concrete of the layers has completely set
Implementation Method 2
at least one reinforcing bar is screwed into the wall, which protrudes through at least this part of the layers
Data Source
Figure 1~2
Figure 3
AI summary
A method for producing a concrete wall (1) of a structure provides that the wall (1) is produced by applying concrete in superimposed layers (4) without lateral formwork. After the application and at least partial hardening of at least a portion of the layers (4), at least one reinforcing bar (7, 8) is screwed into the wall (1), which protrudes through at least this portion of the layers (4). For a concrete wall (1) of a structure, which is constructed from superimposed layers of concrete, it is provided that the wall (1) has at least one reinforcing bar (7, 8) which protrudes through at least a portion of the layers (4). The at least one reinforcing bar (7, 8) has at least one projection (5) on its circumference, wherein all projections of the reinforcing bar (7, 8) form a screw thread (20).