Hardening Accelerator Composition with Low Salt Content
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hardening accelerators for building materials based on calcium silicate hydrate have limitations due to high salt content, corrosiveness, safety concerns, and environmental impact, particularly with the use of calcium chloride and nitrate, which affect their effectiveness and applicability, especially for dry binders.
Innovation Solution
A process for preparing a hardening accelerator composition using calcium hydroxide or calcium oxide reacting with a water-soluble silicate compound in the presence of a water-soluble polymeric dispersing agent with anionic and/or anionogenic groups and polyether side chains, resulting in calcium silicate hydrate particles with a controlled molar ratio, which can be formulated into a powder form for broad applicability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If calcium chloride or calcium nitrate is used as calcium source for hardening accelerator preparation, then the hardening acceleration effect is achieved, but the corrosiveness and safety concerns increase
Solution Approach 1:
The invention extracts and removes the harmful components (chloride and nitrate ions) from the hardening accelerator system by replacing calcium chloride and calcium nitrate with calcium hydroxide and calcium oxide as calcium sources. This extraction of harmful substances eliminates corrosiveness and safety concerns while maintaining the hardening acceleration effect through alternative chemical pathways.
Solution Approach 2:
The invention converts potentially harmful high-alkalinity calcium compounds (calcium hydroxide and calcium oxide) into beneficial components by utilizing their reactivity to form calcium silicate hydrate in a controlled manner. The high alkalinity that could be harmful is instead used to drive the formation of C-S-H particles that accelerate hardening, while the harmful chloride and nitrate ions are completely eliminated.
2Loss of time
If conventional hardening accelerators are used, then setting time is reduced, but the environmental impact and salt content increase
Solution Approach 1:
The invention extracts and eliminates harmful salts (chloride and nitrate) from the hardening accelerator composition by using calcium hydroxide and calcium oxide instead of conventional salt-based calcium sources. This results in an accelerator composition with dramatically reduced anion content, eliminating environmental contamination issues while maintaining effective hardening acceleration.
Solution Approach 2:
The invention changes the chemical composition parameters of the hardening accelerator by replacing traditional high-salt calcium compounds with alternative calcium sources (hydroxide and oxide) that react with silicate to form C-S-H. This parameter change eliminates harmful ions while preserving the acceleration function through controlled particle formation.
3Reliability
If water-based hardening accelerator suspensions are used, then the accelerator effect is achieved, but the applicability to dry binders is limited
Solution Approach 1:
The invention creates a universal hardening accelerator composition based on calcium silicate hydrate particles that can be effectively applied to both wet and dry binder systems. By forming C-S-H particles through reaction of calcium hydroxide/oxide with silicate in the presence of dispersing agents, the accelerator achieves broad adaptability across different application scenarios while maintaining reliable acceleration effects.
Solution Approach 2:
The invention changes the physical state and composition parameters of the hardening accelerator to enable use with dry binders. The formation of fine C-S-H particles with controlled morphology and surface properties allows the accelerator to function effectively in dry powder formulations, expanding applicability beyond water-based suspensions.
4Stability of the object's composition
If high concentration of salts is present in hardening accelerator, then the accelerator composition is stable, but the product activity is reduced upon drying
Solution Approach 1:
The invention extracts and removes harmful salt components from the hardening accelerator composition, replacing them with calcium hydroxide and calcium oxide that form C-S-H particles without leaving residual harmful ions. This eliminates the problem of activity loss upon drying while maintaining composition stability through the formation of stable calcium silicate hydrate 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 provides a hardening accelerator with reduced anion and alkali content, improved safety, and environmental sustainability, enabling effective use in both wet and dry binders with enhanced performance and reduced corrosiveness.
Implementation Method 1
in the presence of at least one water-soluble polymeric dispersing agent which includes anionic and/or anionogenic groups and polyether side chains
Implementation Method 2
water-soluble polymeric dispersing agent which includes anionic and/or anionogenic groups and polyether side chains
Implementation Method 3
reacting a calcium source which is selected from calcium hydroxide and calcium oxide with a water-soluble silicate compound
Data Source
Figure 1
AI summary
The invention relates to a process for the preparation of a hardening accelerator composition by reacting a calcium source selected from calcium hydroxide, calcium oxide with a water-soluble silicate compound in the presence of at least one water-soluble polymeric dispersing agent and the hardening accelerator composition obtainable by said process. The composition has a low content of anions and of alkali cations and is therefore broadly applicable in building material mixtures.