Expanded Glass Granules Metakaolin Water Absorption
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Solution Overview
Problem
Expanded glass granules exhibit high water absorption over time, which affects their long-term stability and performance in applications such as construction materials and fillers.
Innovation Solution
Incorporating metakaolin into the production process of expanded glass granules, along with the use of potassium waterglass and a specific composition of starting materials, enhances chemical stability and reduces water absorption by forming stable aluminosilicates during the foaming process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional starting materials are used to produce expanded glass granules, then the production process is simple, but the granules exhibit high water absorption over time
Solution Approach 1:
The patent applies composite materials by combining metakaolin (an alumina source) with glass cullet and waterglass to form a multi-component starting material mixture. This composite approach creates a more chemically stable expanded glass granule structure that resists water absorption, as the metakaolin forms stable aluminosilicate phases during firing that reduce pore connectivity and improve long-term durability.
Solution Approach 2:
The patent changes the chemical composition parameters of the starting materials by introducing metakaolin at specific proportions (1-10 wt% relative to glass cullet) and adjusting the waterglass modulus. These parameter changes in the chemical formulation lead to improved chemical stability and reduced water absorption in the final expanded granules while maintaining the foaming process effectiveness.
2Object-affected harmful factors
If metakaolin is added to the starting materials, then water absorption is reduced and chemical stability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-mixing the starting materials in optimal proportions before the foaming process. The metakaolin, glass cullet, and waterglass are thoroughly mixed to ensure homogeneous distribution of the alumina source throughout the batch, which simplifies the overall process by eliminating the need for complex in-process adjustments and ensures consistent product quality.
Solution Approach 2:
The patent applies self-service by utilizing the exothermic reaction characteristics of the waterglass-metakaolin system during firing. The chemical reactions between waterglass and metakaolin generate heat that contributes to the foaming process, reducing the external energy input required and simplifying process control while achieving the desired granule expansion and structural stability.
3Ease of manufacture
If metakaolin is used as a separating agent in the firing oven, then granules do not stick to the oven wall, but metakaolin consumption increases production cost
Solution Approach 1:
The patent applies universality by making metakaolin serve dual functions: (1) as a chemical additive in the starting material mixture that improves granule stability and reduces water absorption through aluminosilicate formation, and (2) as a separating agent in the firing oven that prevents granule adhesion to oven walls. This multi-functionality eliminates the need for separate separating agent materials and reduces overall metakaolin consumption while achieving both manufacturing ease and product quality improvement.
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 method results in expanded glass granules with significantly reduced long-term water absorption, achieving values below 25 volume % after 21 days, and improved chemical stability, making them suitable for durable applications.
Implementation Method 1
the kaolinite (Al4[(OH)8Si4O10]), which is the primary constituent of kaolin, is calcined by the action of heat in the firing oven at temperatures of around 700° C., in accordance with the formula Al4[(OH)8Si4O10]→2(Al2O3×2SiO2)+4H2O, to form metakaolin (Al2O3×2SiO2), with the liberated water being evaporated.
Implementation Method 2
the kaolinite (Al4[(OH)8Si4O10]), which is the primary constituent of kaolin, is calcined by the action of heat in the firing oven at temperatures of around 700° C.
Implementation Method 3
This foaming operation is driven here by formation of gas, which is caused by evaporation or chemical reaction of the expandant.
Implementation Method 4
This foaming operation is driven here by formation of gas, which is caused by evaporation or chemical reaction of the expandant.
Implementation Method 5
This effect is based, as has been recognized, in particular on the partial dissolution of metakaolin even while the slip is being produced, in other words in the aqueous batch of the starting materials. In the course of this partial dissolution, aluminum is leached out, diffuses into the waterglass matrix during the subsequent foaming operation
Implementation Method 6
In the course of this partial dissolution, aluminum is leached out, diffuses into the waterglass matrix during the subsequent foaming operation
Data Source
AI summary
In a method for producing an expanded-glass granular material, starting materials containing glass powder, water glass, at least one blowing agent, and metakaolin, are mixed in order to form a homogeneous slurry. The slurry is granulated to form raw granular-material particles, which are foamed at a baking temperature between 780° C. and 950° C. in order to form expanded-glass granular-material particles. The expanded-glass granular material has a long-term water absorption of less than 25 volume percent when the expanded-glass granular material is exposed to water for a time period of 21 days.