Shellac-Coated Accelerator Particles for Cement Workability Control

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Solution Overview

Problem

In cementitious systems, achieving a balance between workability and setting time is challenging, as potent accelerators for fast setting shorten workability time, and vice versa, making it difficult to achieve long workability with short setting times without causing 'flash-setting'.

Innovation Solution

Development of internally triggered, osmatically controlled release particles with shellac coating, which releases the accelerator after a delay, allowing for adjustable workability and setting times, using shellac as a coating that changes from water-soluble to insoluble and permeable, ensuring a quick release when osmotic pressure builds up.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a higher dosage or more potent accelerator is used to achieve fast setting, then setting time is reduced, but workability time is shortened

Engineering Contradiction:

Improvesetting speedVSAvoidworkability time

Core Design Contradiction:

SpeedVSDuration of action of moving object

Solution Approach 1:

The accelerator is pre-loaded into the core of coated particles, but its release is delayed until after the coating dissolves. This preliminary positioning allows the accelerator to be ready for action at the precise moment needed, separating the workability phase from the setting phase effectively.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A water-soluble coating material acts as an intermediary barrier between the accelerator core and the mortar matrix. This coating delays the release of the accelerator, allowing workability to be maintained while ensuring fast setting occurs after the coating dissolves in the presence of moisture.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If accelerator is released immediately after activation, then setting occurs quickly, but workability time is reduced

Engineering Contradiction:

Improvesetting speedVSAvoidworkability time

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The release of the accelerator occurs in a periodic manner: first the coating dissolves over time (maintaining workability), then the accelerator is released in a concentrated burst (triggering fast setting). This periodic release pattern solves the contradiction between extended workability and rapid setting.

Inventive Principle:

Principle #19Periodic action

3Ease of manufacture

If a coating is water-soluble before application, then it is easy to apply, but it dissolves too quickly in the mortar

Engineering Contradiction:

Improvecoating application easeVSAvoidcoating durability

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The coating material's solubility parameter is changed by the alkaline environment of the mortar. The coating is formulated to be stable at neutral pH during application and storage, but dissolves when exposed to the high pH (above 10) environment of hydrated cement, providing the desired delayed release timing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The coating undergoes a phase transition from a stable, intact state during application to a dissolving state when exposed to the alkaline mortar environment. This phase change is triggered by the pH shift, allowing the coating to maintain its integrity during manufacturing and application, then dissolve controllably in the mortar to release the accelerator.

Inventive Principle:

Principle #36Phase transitions

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 allows for homogeneous and controlled release of the accelerator, enabling long workability with fast setting, maintaining mortar properties over time without the risks of flash-setting, and ensuring the active ingredient is evenly distributed throughout the mortar.

Implementation Method 1

shellac as a coating that changes from water-soluble to insoluble and permeable, ensuring a quick release when osmotic pressure builds up

Methodology Applied

Scientific EffectpH-dependent solubility change:

Implementation Method 2

releases the accelerator after a delay, allowing for adjustable workability and setting times, using shellac as a coating that changes from water-soluble to insoluble and permeable, ensuring a quick release when osmotic pressure builds up

Methodology Applied

Scientific EffectOsmotic pressure: Osmotic Pressure

Data Source

PatentEP2791076B1Process for manufacture of shellac-coated particles of active ingredients with controlled release properties at high ph-values

Publication Date: 2017.10.18 CONSTRUCTION RESEARCH & TECHNOLOGY GMBH

AI summary

Suggested is a novel coated particleof active ingredients with controlledrelease properties at pH-valuesfrom 10 to 14, wherein the active ingredient is selected from one or more construction chemical additives for the control of inorganic binders, characterized in that the coating comprises shellac, a process for its manufacture and the use thereof as an additive for mortars, dry mortars, cement slurries and/or concretes.