3D Printable Clay-Based Mortar Reducing Cement Viscosity
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Solution Overview
Problem
The challenges of 3D printing with cement include the high viscosity of cement, which makes it difficult to pump over long distances and through complex piping systems, and the environmental impact and cost associated with sourcing cement materials for large-scale projects.
Innovation Solution
A 3D printable clay-based mortar cementitious ink is developed, which includes Type I/II Portland cement, calcined clay, ground calcium carbonate, sand, and liquid admixtures. This formulation reduces the amount of Portland cement and incorporates calcined clay, which improves the fluidity and workability of the mortar, allowing it to be pumped and extruded effectively for 3D printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional Portland cement is used for 3D printing, then structural strength is achieved, but viscosity is too high for effective pumping and extrusion
Solution Approach 1:
The patent uses a composite binder system combining Portland cement with calcined clay (metakaolin) and limestone filler. This composite material approach allows the mixture to achieve both adequate structural strength and improved workability for pumping and extrusion, as the clay and limestone components modify the rheological properties while contributing to strength development.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the cementitious mixture by incorporating specific ratios of calcined clay (15-30% by weight) and limestone filler (10-25% by weight), along with controlled water-to-binder ratios and chemical admixtures. These parameter changes optimize both the viscosity for pumping and the compressive strength performance.
2Strength
If high amounts of Portland cement are used, then structural performance is achieved, but greenhouse gas emissions and cost increase
Solution Approach 1:
The patent replaces a significant portion (40-60% by weight) of Portland cement with calcined clay and limestone filler, thereby discarding the need for large amounts of high-emission cement while recovering and utilizing locally available clay and limestone resources. This substitution maintains structural performance while reducing the carbon footprint associated with cement production.
Solution Approach 2:
The patent utilizes abundant, low-cost local materials such as clay and limestone that can be sourced near construction sites, replacing expensive and environmentally costly Portland cement. These local materials provide adequate performance for the application while being more economically and environmentally sustainable.
3Ease of operation
If cement mixture is made more fluid for pumping, then pumpability improves, but structural strength and stability deteriorate
Solution Approach 1:
The patent introduces chemical admixtures as intermediaries to decouple the relationship between fluidity and strength. Specifically, superplasticizers and viscosity-modifying admixtures are used to achieve the desired rheological properties for pumping while maintaining the structural integrity and strength development of the cementitious mixture.
Solution Approach 2:
The patent carefully controls the water-to-binder ratio and incorporates specific admixture dosages to achieve optimal rheological parameters that allow fluidity for pumping without compromising strength. The calcined clay and limestone filler also contribute to optimizing the flow characteristics while maintaining structural performance.
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 printable mortar achieves the target structural performance while reducing greenhouse gas emissions and utilizing locally available source materials. It exhibits improved fluidity, workability, and green strength, enabling faster and more efficient 3D printing with reduced environmental impact.
Implementation Method 1
calcined clay, which improves the fluidity and workability of the mortar, allowing it to be pumped and extruded effectively
Implementation Method 2
calcined clay, which improves the fluidity and workability of the mortar
Implementation Method 3
Cement is a fine powder of primarily hydraulic calcium silicates that hardens when water is added to form durable structures
Data Source
AI summary
A 3D printable clay-based mortar cementitious ink includes a blend of commercially available Portland cement, calcium carbonate, sand, and calcined clay. The calcined clay is produced from the calcination of clay having a high kaolinite content of greater than about 60%. The clay is calcined at a temperature of between about 600° C. and about 800° C., preferably between about 650° C. and about 850° C., for a period of one to two hours. In a preferred embodiment, a ratio of calcined clay to Portland cement is about 0.148, a ratio of calcium carbonate to Portland cement is about 0.333, and a ratio of sand to Portland cement is approximately about 3.0. The ratio of water to powder (clay, cement, calcium carbonate, and sand) may range between 0.39 and 0.40.