Cementitious Mixture Viscosity Control for 3D Printing Extrudability
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Solution Overview
Problem
Current cementitious mixtures for 3D extrusion printing face challenges in achieving optimal extrudability, buildability, and mechanical strength within short deadlines, with existing formulations often having poor mechanical strength at 24 hours and requiring specific characteristics not found in standard 3D printers.
Innovation Solution
A cementitious mixture comprising cement, latent hydraulic addition, filler, aggregates, additives, and water, optimized with specific particle size distributions and additive combinations to achieve a viscosity range of 80,000 Pa·s to 150,000 Pa·s, ensuring excellent extrudability, buildability, and enhanced mechanical strength at 24 hours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cementitious mixture viscosity is increased to improve buildability, then extrudability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the viscosity of the cementitious mixture within the range of 80,000-150,000 Pa·s at a shear rate of 0.01 s^-1. This specific viscosity parameter optimization resolves the contradiction by finding the optimal balance point where the mixture has sufficient thickness for buildability while remaining extrudable through the nozzle system.
Solution Approach 2:
The patent uses composite materials by combining cement or hydraulic binder with latent hydraulic addition, filler, aggregates, and additives in specific proportions. This composite formulation achieves both buildability and extrudability by leveraging the synergistic effects of different materials - the binder provides structure, the filler controls viscosity, and the additives modify rheological properties to satisfy both contradictory requirements.
2Ease of manufacture
If cementitious mixture formulation is optimized for extrudability, then mechanical strength at 24 hours deteriorates
Solution Approach 1:
The patent employs composite materials by incorporating latent hydraulic addition (1-30% by weight) alongside cement and other components. This composite approach ensures that the mixture remains extrudable while the latent hydraulic addition contributes to early strength development at 24 hours, resolving the contradiction between ease of manufacturing and early mechanical strength.
Solution Approach 2:
The patent applies parameter changes by optimizing the water-to-binder ratio and incorporating specific additives that affect both extrudability and strength development. The controlled viscosity range and chemical composition parameters enable the mixture to be easily extruded while simultaneously achieving improved mechanical strength within 24 hours through controlled hydration and setting characteristics.
3Manufacturing precision
If particle size distribution is refined for better print resolution, then extrusion speed deteriorates
Solution Approach 1:
The patent applies parameter changes by specifying a maximum aggregate diameter of less than 1 mm and controlling the particle size distribution of filler and aggregates. This particle size optimization resolves the contradiction by ensuring fine enough particles for high print resolution while maintaining a graded distribution that prevents clogging and enables sustained extrusion speed throughout the printing process.
Data Source
AI summary
A cementitious mixture for a 3D printer and its relative use are described, more specifically for the production of finished products having a complex geometry using a 3D printing apparatus.