3D-Printed Cementitious Mixture Rheology Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing 3D printing technologies face challenges with hydraulic binders having short initial setting times, which lead to material buildup in equipment and limited operational flexibility, while also requiring high printing speed and strong interlayer bonding for structural stability.
Innovation Solution
A dry cementitious material mixture for 3D printing comprising hydraulic cement, viscosity-enhancing admixtures, and clay, eliminating the need for additional admixtures at the deposition head, providing a consistent and stable fresh mortar or concrete composition with increased yield strength and thixotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hydraulic binder with a short initial setting time is used, then the mechanical stability of deposited layers is improved, but material buildup in mixing devices and pumps increases
Solution Approach 1:
The patent changes the rheological parameters of the fresh concrete by adding viscosity-enhancing admixtures (cellulose ethers, associative thickeners) to modify the flow behavior and yield stress, allowing the material to remain pumpable while developing sufficient strength to support subsequent layers without excessive buildup
Solution Approach 2:
The patent creates a composite system combining hydraulic binder, viscosity-enhancing admixtures, and specific aggregate distributions to achieve a material that simultaneously provides early strength development and reduced adhesion to equipment surfaces
2Speed
If a hydraulic binder with a short initial setting time is used, then the printing speed is improved, but the operational flexibility is reduced
Solution Approach 1:
The patent modifies the rheological parameters (yield stress, plastic viscosity) through viscosity-enhancing admixtures to extend the working time window, allowing slower printing speeds while maintaining layer stability, thus improving operational flexibility without sacrificing printing efficiency
3Strength
If a hydraulic binder with a short initial setting time is used, then the interlayer adhesion is improved, but the time for adjustments during construction is reduced
Solution Approach 1:
The patent adjusts the rheological parameters to achieve optimal yield stress values that maintain layer shape and support subsequent layers while extending the setting time, providing a wider window for construction adjustments without compromising interlayer bonding quality
4Ease of operation
If the fresh concrete has low yield stress for good pumpability, then the ease of operation is improved, but the mechanical stability of deposited layers deteriorates
Solution Approach 1:
The patent optimizes the yield stress parameter to a specific range that balances pumpability and layer stability, using viscosity-enhancing admixtures to achieve sufficient yield stress for mechanical stability while maintaining flowability for easy pumping and deposition
Solution Approach 2:
The patent creates a dynamic rheological behavior where the concrete exhibits shear-thinning properties, allowing it to flow easily during pumping and deposition then rapidly develop yield stress to support subsequent layers, effectively adapting its mechanical properties to different operational phases
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
The solution enables non-stop continuous 3D printing with improved mechanical stability, reduced material buildup, and enhanced operational flexibility, allowing for high-strength structures with consistent quality and cost savings.
Implementation Method 1
The at least one viscosity enhancing admixture and the clay are present in an amount to increase the yield stress of the fresh mortar or concrete composition immediately after placing and/or after a defined period of time
Implementation Method 2
the combined amount of the at least one viscosity enhancing admixture and of the clay is selected in order to achieve a yield stress of 0.5-1.5 kPa, preferably 0.5-3 kPa, immediately after placing the fresh mortar or concrete composition
Implementation Method 3
3d printed elements also require a strong bonding strength between the deposited layers
Data Source
AI summary
A dry cementitious material mixture for 3D-printing, includes a hydraulic cement, at least one viscosity enhancing admixture, and clay and optionally aggregates, wherein the at least one viscosity enhancing admixture is present in an amount of 0.05-1.5% by weight based on the hydraulic cement and the clay is present in an amount of 0.01-5.0% by weight based on the hydraulic cement.