Geopolymer Composition with Calcined Clay and Kaolin for Thermal Resistance
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Solution Overview
Problem
Geopolymers lack enhanced flame retardant and mechanical properties, limiting their applications in thermal protection and industrial waste management.
Innovation Solution
A composition comprising a powdery alumino-silicate mixture of clay and kaolin, mixed with an alkaline aqueous solution of alkali metal silicate, undergoes calcination and polycondensation to form a geopolymer that can be heat-treated for improved mechanical reinforcement and thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional geopolymers are used, then they provide basic thermal resistance, but they lack enhanced flame retardant and mechanical properties
Solution Approach 1:
The invention uses a composite material system combining clay material (A1) with specific composition (30-70% SiO2, 10-40% Al2O3, 5-20% CaO, 0.5-6% MgO) and kaolin (A2) in a powdery alumino-silicate mixture. This composite formulation, when activated with alkaline aqueous solution, creates a geopolymer that simultaneously achieves enhanced mechanical strength and flame retardancy through the synergistic effect of its constituents, particularly calcium and magnesium compounds that contribute to both structural integrity and thermal stability.
Solution Approach 2:
The invention changes the chemical composition parameters of the geopolymer precursor by specifying precise ranges of SiO2, Al2O3, CaO, and MgO content in the clay material. By controlling these compositional parameters and the calcination temperature (500-900°C), the resulting geopolymer achieves optimized balance between mechanical resistance and flame retardant properties, transforming the material's inherent characteristics through parameter optimization.
2Object-affected harmful factors
If geopolymers are used for thermal protection, then they provide fire protection, but their mechanical properties remain insufficient for enhanced applications
Solution Approach 1:
The geopolymer composition employs a composite approach by integrating clay material rich in calcium and magnesium oxides with kaolin. This composite structure provides inherent fire protection through the formation of stable crystalline phases during calcination and subsequent heat treatment, while simultaneously enhancing mechanical properties through the reinforced geopolymer matrix formed by alkaline activation and polycondensation reactions.
Solution Approach 2:
The invention optimizes mechanical properties while maintaining fire protection by controlling the calcination temperature range (500-900°C) and the composition ratios of clay to kaolin (10-75 parts A1 to 90-25 parts A2). These parameter changes enable the formation of a dense, mechanically strong geopolymer structure that retains excellent fire resistance, allowing the material to satisfy both fire protection and mechanical strength requirements.
3Ease of manufacture
If clay and kaolin are mixed and calcined, then reactive alumino-silicate mixture is formed, but additional processing steps are required to achieve enhanced properties
Solution Approach 1:
The invention applies preliminary action by pre-mixing and calcining the clay material and kaolin together before geopolymerization. This pre-calcination step (at 500-900°C) activates the alumino-silicate precursors and forms reactive phases that facilitate subsequent geopolymer formation, simplifying the overall process by combining material preparation and activation in one preparatory stage before mixing with the alkaline solution.
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 geopolymer exhibits increased mechanical resistance and flame retardancy, suitable for thermal protection barriers and refractory applications, with enhanced performance after heat treatment.
Implementation Method 1
the constituents (A1) and (A2) having been mixed then calcined to form said powdery alumino-silicate mixture (A)
Implementation Method 2
Solid matrices are then obtained by polycondensation reactions of alkaline silicates
Implementation Method 3
during a subsequent 'heat treatment ', voluntary or not, in particular by causing the formation of calcium silicates, zeolite or aluminates (spinel structure type) acting as mechanical reinforcements
Implementation Method 4
by causing the formation of calcium silicates, zeolite or aluminates (spinel structure type) acting as mechanical reinforcements in the material after thermal transient
Data Source
Figure 1(a)~1(g)
Figure 2
Figure 3
AI summary
The invention relates to a composition for forming a geopolymer, characterised in that it comprises: (A) an alumino-silicate powder mixture made up of: (A1) 10 to 75 parts by weight of at least one clay material having, by mass composition (by % mass): • 30 to 70 % of SiO2; • 10 to 40 % of Al2O3; • 5 to 20 % of CaO; • 0.5 to 6 % of MgO, and (A2) 90 to 25 parts by weight of at least one kaolin, with (A1) + (A2) representing 100 parts by weight, and the constituents (A1) and (A2) having being mixed, then calcinated to form said alumino-silicate powder mixture (A); and (B) an alkaline aqueous solution of at least one alkaline metal silicate; the constituents (A) and (B) being intended to be mixed to form a reactive colloidal solution able to provide said geopolymer by hardening.