Quick-Setting Slurry Admixture for Cement Concrete
Solution Overview
Problem
Conventional quick-setting admixtures for spraying in tunnel and underground applications face issues with high pH levels, dust formation, and solidification in tools, leading to inadequate initial strength and quick-setting properties, especially when using liquid admixtures with cement compositions containing alkali components.
Innovation Solution
A slurry quick-setting admixture comprising water, alkaline earth metal carbonate, a water-soluble acidic substance, calcium aluminate, and alkali metal sulfate, combined with a powder admixture containing a blowing agent and calcium aluminate, is used to form a slurry that is mixed with cement concrete and sprayed, preventing solidification in tools and enhancing quick-setting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a liquid quick-setting admixture is used, then the mixing efficiency is improved, but the initial strength is hardly obtainable and the danger of falling increases when sprayed thickly
Solution Approach 1:
The patent changes the physical state of the quick-setting admixture from liquid to powder form, and adjusts the chemical composition by incorporating calcium aluminate and aluminum sulfate in specific ratios. This parameter change enables the admixture to provide both easy mixing and sufficient initial strength, resolving the contradiction between productivity and strength.
Solution Approach 2:
The patent creates a composite powder admixture combining calcium aluminate and aluminum sulfate with specific additives. This composite formulation achieves both good mixing properties and adequate initial strength, eliminating the need to choose between liquid admixtures (easy mixing but weak) and conventional powder admixtures (strong but difficult to mix).
2Productivity
If compressed air is used to disintegrate concrete for mixing, then the mixing efficiency is increased, but the amount of compressed air increases and dust formation increases
Solution Approach 1:
The patent employs a disposable Y-tube mixing device that is simple in structure and easy to dispose of. This eliminates the need for complex, reusable mixing equipment that would require maintenance and cleaning, thereby reducing dust generation while maintaining high mixing efficiency through the simple compressed air disintegration method.
Solution Approach 2:
The patent extracts the mixing function from complex equipment and implements it through a simple Y-tube device that uses compressed air to disintegrate concrete. This extraction simplifies the mixing process, reduces dust generation, and maintains high productivity by eliminating the need for elaborate mixing mechanisms.
3Productivity
If a Y-tube is used to add quick-setting admixture, then the mixing efficiency is improved, but the amount of compressed air increases and dust formation increases
Solution Approach 1:
The patent uses a disposable Y-tube that is optimized for single-use or easy replacement. This simple, low-cost device achieves efficient mixing with minimal compressed air consumption, eliminating the need for energy-intensive, reusable mixing equipment while maintaining high productivity.
4Speed
If aluminum sulfate is used as a quick-setting admixture component, then the quick-setting property is improved, but the pH-value becomes too high and alkali reagent damage occurs
Solution Approach 1:
The patent carefully controls the ratio of aluminum sulfate to calcium aluminate in the powder admixture, and adds specific additives to modulate the pH level. This parameter optimization maintains the quick-setting property while preventing excessive alkalinity, thereby resolving the contradiction between setting speed and chemical compatibility.
Solution Approach 2:
The patent creates a composite powder admixture combining aluminum sulfate with calcium aluminate and other additives in specific proportions. This composite formulation achieves fast setting while balancing the pH to prevent alkali reagent damage, eliminating the need to choose between high setting speed and chemical safety.
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 effectively controls solidification in tools, improves the quick-setting and durability of cement concrete, while reducing dust formation and enhancing adhesive properties, providing a more efficient quick-setting property compared to conventional methods.
Implementation Method 1
one having a fluorine element incorporated to aluminum sulfate was developed... a technique for combining a liquid quick-setting admixture and a powder quick-setting admixture has also been published... liquid quick-setting admixture comprising aluminum sulfate, a calcium aluminate, a water-reducing agent and water, to cement concrete containing an inorganic powder
Implementation Method 2
a technique for combining a liquid quick-setting admixture and a powder quick-setting admixture has also been published... powder admixture comprising a blowing agent and calcium aluminate
Data Source
AI summary
A slurry quick-setting admixture comprising an alkaline earth metal carbonate, a water-soluble acidic substance, calcium aluminate, an alkali metal sulfate, and water; and a quick-setting cement concrete comprising such a slurry quick-setting admixture and cement concrete. The slurry quick-setting admixture may further contain calcium sulfate, calcium hydroxide and/or aluminum hydroxide, a retarder, etc. The spraying method comprises mixing water and a powder quick-setting admixture comprising an alkaline earth metal carbonate, a water-soluble acidic substance, calcium aluminate and an alkali metal sulfate, to form a slurry quick-setting admixture, mixing this slurry quick-setting admixture with cement concrete to form a quick-setting cement concrete, and spraying this quick-setting cement concrete.