Porous-Substrate Accelerator Powder for Lump-Resistant Dry Mortars
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Solution Overview
Problem
Existing accelerators for dry mortars and concretes, such as alkanolamines and calcium chloride, face issues with handling, lump formation, hydration reactions, and hygroscopic behavior, making them impractical for dry-mix formulations, and require complex dosage and mixing processes.
Innovation Solution
A free-flowing powder composition is developed with a porous substrate functionalized with a solid hygroscopic or deliquescent accelerator, ensuring the accelerator remains on the substrate's surface and quickly dissolves in water without penetrating into pores, allowing easy handling and effective acceleration of setting and reducing aging effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid accelerators (e.g., alkanolamines) are added during dry mixing, then accelerating effect is achieved, but lumps formation and handling difficulties occur
Solution Approach 1:
The accelerator is transformed from liquid state to solid state by changing its physical parameters (phase change), allowing it to be handled as a free-flowing powder while maintaining its accelerating functionality when water is added
Solution Approach 2:
A porous substrate acts as an intermediary carrier that holds the accelerator in solid form, enabling easy handling during dry mixing while releasing the accelerator effectively when water is introduced to the mortar or concrete
2Reliability
If hygroscopic accelerators (e.g., calcium chloride) are used in dry-mix formulations, then accelerating effect is achieved, but lumps formation and ageing occur due to moisture absorption
Solution Approach 1:
The porous substrate serves as a moisture barrier that prevents atmospheric humidity from reaching the hygroscopic accelerator, keeping it stable during storage while allowing controlled release when water is deliberately added to the mixture
Solution Approach 2:
The porous substrate acts as a protective intermediary layer between the hygroscopic accelerator and atmospheric moisture, preventing premature hydration and lump formation during storage and handling
3Reliability
If accelerators are used to compensate cementitious binder ageing, then setting acceleration is achieved, but dust generation increases
Solution Approach 1:
The accelerator is combined with a porous substrate to form a composite material system, where the substrate acts as a dust-suppressing carrier that reduces fine particle generation while maintaining the accelerator's effectiveness
Solution Approach 2:
The porous substrate serves as an intermediary that binds accelerator particles together, reducing dust generation during handling while allowing effective release when water is added to the mixture
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 dry, free-flowing powder that accelerates hardening, reduces aging, and minimizes dust, while maintaining the accelerator's effectiveness and safety by ensuring it remains on the substrate's surface, thus avoiding hydration and lump formation issues.
Implementation Method 1
the porous substrate keeps the accelerator in a dry state during storage and handling, yet allows its quick release in water
Implementation Method 2
after 15 minutes of immersion of said free-flowing powder composition in water at 20°C at least 80% in weight of said accelerator is solubilized
Data Source
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AI summary
The present invention relates to a free-flowing powder composition comprising at least one substrate, said substrate having pores and an external surface between said pores, wherein said external surface is functionalized with at least one accelerator for a hydraulic setting composition, said accelerator being liquid, or hygroscopic or deliquescent, and wherein after 15 minutes of immersion of said free-flowing powder composition in water at 20°C at least 80% in weight of said accelerator is solubilized, provided that said free-flowing powder composition is immersed in an amount of water sufficient so that the saturation concentration of said accelerator cannot be reached. The invention also relates to a method for preparing said free-flowing powder composition. The invention is further directed to the use of said free-flowing powder composition as an additive for mortar or concrete composition so as to provide an accelerating effect, an anti-ageing effect and an anti-dusting effect. The invention additionally concerns a dry mortar or concrete composition comprising a hydraulic binder, said free-flowing powder composition and a granulate, wet mortar or concrete composition and hardened body obtained therefrom.