C-S-H Accelerator Composition for Cement Strength
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Solution Overview
Problem
Current cement-based building materials face challenges in achieving high early strengths without compromising final strengths, particularly in dry mortar systems, and existing accelerators like calcium nitrate and chloride-based compounds can harm corrosion resistance and cause efflorescence.
Innovation Solution
A process involving the mixing of an aqueous suspension containing calcium silicate hydrate with a water-soluble comb polymer, followed by dilution and drying, to produce solid compositions that act as efficient curing accelerators for cement-based systems, enhancing early strength without affecting final strength and minimizing water content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional accelerators (calcium nitrate, calcium chloride, calcium formate) are used to increase early strength, then setting acceleration is achieved, but corrosion resistance deteriorates and efflorescence occurs
Solution Approach 1:
The invention changes the chemical composition parameters by replacing traditional salt-based accelerators with calcium silicate hydrate (C-S-H) particles, fundamentally altering the acceleration mechanism from ionic to colloidal/nucleation-based, thereby eliminating corrosion and efflorescence while maintaining setting acceleration
Solution Approach 2:
The invention creates a composite accelerator system combining calcium silicate hydrate particles with water-soluble comb polymer, where the C-S-H provides acceleration through nucleation and the polymer provides dispersion and adhesion, achieving both performance and durability
2Strength
If water-containing suspensions of calcium silicate hydrate are used to achieve high early strength, then early strength is significantly increased, but water content causes premature hydration and reduces ease of operation in dry mortar systems
Solution Approach 1:
The invention utilizes phase transition from liquid suspension to solid powder through spray drying, transforming the accelerator into a stable dry form that can be stored and handled without premature hydration, yet still delivers high early strength when reconstituted
Solution Approach 2:
The invention performs preliminary drying of the C-S-H suspension before use, creating a pre-prepared dry accelerator that eliminates water-related problems during storage and handling while maintaining the acceleration effectiveness when added to the mortar mix
3Speed
If conventional pulverulent accelerators are used to achieve high early strength, then setting acceleration is obtained, but the amount required is large and productivity is reduced
Solution Approach 1:
The invention changes the physical state and surface properties of the accelerator by using spray-dried C-S-H particles with controlled morphology and surface area, increasing the specific surface area and reactivity per unit mass, thereby reducing the required dosage while maintaining acceleration effectiveness
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 resulting compositions significantly increase early strength in cement-based systems while maintaining final strength, reducing water usage, and preventing efflorescence, thus overcoming the limitations of existing accelerators.
Implementation Method 1
WO 2010/026155 A1 also indicates that the suspensions can be dried by conventional processes such as spray drying. However, for practical reasons, it is not possible to formulate dry mortar mixtures containing essentially (portland) cement as binder or other binder systems which set hydraulically in the presence of water using the water-containing suspensions of calcium silicate hydrate (C—S—H) since the water content of the suspensions would lead to an unacceptable, at least partially premature hydration of the binder.
Implementation Method 2
mixing of an aqueous suspension containing calcium silicate hydrate which is optionally suitable as setting and curing accelerator for (portland) cement-containing binder systems
Data Source
AI summary
A process for producing solid compositions containing calcium silicate hydrate (C—S—H) and a water-soluble comb polymer which is suitable as plasticizer for hydraulic binders, wherein the following process steps are carried out: a) contacting of an aqueous C—S—H-containing suspension with at least one comb polymer, b) optionally setting a suitable solids content of the product from step a) by dilution with water and c) drying of the product from step a) or b). The process products which can be obtained, the use thereof in building material mixtures, in particular, containing cement, the use as grinding aid in the production of cement and corresponding building material mixtures are likewise provided.