Cementitious Composition for 3D Printing Stability

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Solution Overview

Problem

Cementitious materials used in three-dimensional printing face issues with inconsistency and instability when extruded through a nozzle, leading to poor workpiece quality and inaccurate dimensions due to insufficient static yield stress, which previous solutions have not adequately addressed.

Innovation Solution

A cementitious composition comprising cement, fine aggregate, powdered limestone, expanding admixture, retarding admixture, thickener, and rheology modifier is developed, with specific ratios and properties to enhance static yield stress and flowability, ensuring stability and accuracy in extrusion printing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cementitious material is used for three-dimensional extrusion printing, then environmental resistance and cost-effectiveness are improved, but consistency and dimensional accuracy of printed lines deteriorate

Engineering Contradiction:

Improveenvironmental resistanceVSAvoiddimensional accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent modifies the rheological parameters of cementitious material by adding specific additives (hydroxyethyl cellulose, sodium carboxymethyl cellulose, or carboxymethyl starch) to control flowability and stability. This allows the material to maintain dimensional accuracy during extrusion while preserving the environmental resistance benefits of cementitious materials.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system combining cementitious material with cellulose-based or starch-based thickening agents. This composite approach improves print consistency and dimensional accuracy by controlling material flow properties without sacrificing the inherent environmental resistance of cementitious materials.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If amount of mortar is reduced to solve dimensional accuracy, then dimensional accuracy is improved, but continuity of printed line deteriorates

Engineering Contradiction:

Improvedimensional accuracyVSAvoidcontinuity of printed line

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent adjusts the flowability parameter of the cementitious material through controlled addition of thickening agents. This enables the material to be extruded in consistent, continuous lines with accurate dimensions, simultaneously achieving both dimensional accuracy and line continuity that were previously conflicting goals.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If cementitious material is extruded through nozzle, then three-dimensional printing formation is achieved, but static yield stress is insufficient causing instability

Engineering Contradiction:

Improveextrusion printing formationVSAvoidstatic yield stress

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent modifies the static yield stress parameter of cementitious material by incorporating specific thickening agents in controlled amounts (0.1-5.0 wt%). This enhancement provides sufficient stability to maintain printed line shapes and prevent deformation, while still allowing easy extrusion through the nozzle during the printing process.

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If cementitious material is used for extrusion printing, then cost-effectiveness is improved, but homogeneity and strength of workpiece deteriorate

Engineering Contradiction:

Improvecost-effectivenessVSAvoidworkpiece strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent optimizes the water-to-cement ratio and additive concentrations to achieve homogeneous material distribution during extrusion. This controlled parameter adjustment ensures uniform curing and consistent strength development throughout the workpiece, maintaining cost-effectiveness while improving homogeneity and overall strength.

Inventive Principle:

Principle #35Parameter changes

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 composition provides a stable and consistent extrusion process, resulting in improved workpiece fineness, accuracy, and increased compressive strength, making the printing process more convenient and effective.

Implementation Method 1

a cementitious composition comprising cement, fine aggregate, powdered limestone, expanding admixture, retarding admixture, thickener and rheology modifier

Methodology Applied

Scientific EffectViscosity enhancement:

Implementation Method 2

expanding admixture 0.1-5% by weight of dry binding material

Methodology Applied

Scientific EffectExpansion:

Implementation Method 3

retarding admixture 0.1-1.5% by weight of dry binding material

Methodology Applied

Scientific EffectHydration retardation:

Data Source

PatentUS10934214B2Binding material suitable for three-dimensional printing formation

Publication Date: 2021.03.02 SCG CEMENT CO LTD

AI summary

A cementitious composition suitable for formation by three-dimensional printing according to the present invention is aimed at developing a cementitious composition suitable for formation by three-dimensional printing which gives good stability to the extruded material coming out of a nozzle. The workpiece obtained from the three-dimensional printing formation therefore has fewer errors and greater fineness and is easier to use. The cementitious composition comprises cement, fine aggregate, powdered limestone, expanding admixture, retarding admixture, thickener and rheology modifier.