Aerated Concrete Moulding Sedimentation Control
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Solution Overview
Problem
Current methods for producing unreinforced aerated concrete moldings with high relative compressive strength face challenges such as sedimentation issues due to high water/solids values and the acidic reaction of aluminum sulfate, leading to increased corrosion and foaming, which limits the achievable A number to below 1600 and thermal conductivity above 0.085 W/mK.
Innovation Solution
The use of polysaccharides, polyethylene glycol, polyethylene oxide, or melamine resin derivatives as sedimentation inhibitors in combination with SiO2 components of specific surface areas and adjusted water/solids ratios to produce aerated concrete moldings with A numbers over 1600 and thermal conductivities ≤ 0.085 W/mK, without aluminum sulfate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aluminum sulfate is used as a blowing agent with high water/solids values to achieve high strength aerated concrete moldings, then the A number increases, but sedimentation occurs and corrosion increases
Solution Approach 1:
The patent introduces an intermediary substance (polymer additive) that mediates between the blowing agent and the cementitious matrix. This additive acts as a bridge that allows the aluminum sulfate to function as a blowing agent while preventing the harmful side effects of sedimentation and corrosion through its polymer structure
Solution Approach 2:
The patent changes the chemical and physical parameters of the casting compound by introducing a polymer additive with specific molecular weight and concentration ranges. This parameter change modifies the rheological properties and chemical environment to prevent sedimentation while maintaining the blowing agent's effectiveness
2Strength
If aluminum sulfate is used to produce aerated concrete moldings, then the A number can be increased, but thermal conductivity increases above 0.085 W/mK
Solution Approach 1:
The patent modifies the physical-chemical parameters of the casting compound through the addition of polymer additives, which alter the pore structure formation and gas distribution during aeration. These parameter changes enable achieving high A numbers while controlling thermal conductivity at or below 0.085 W/mK
3Strength
If high water/solids values are used in the casting compound to achieve high strength, then the A number increases, but sedimentation of solids occurs
Solution Approach 1:
The polymer additive serves as an intermediary that stabilizes the suspension of solid particles in the high water/solids casting compound. It creates a protective environment around the solids, preventing them from settling while allowing the mixture to maintain its high water content for improved workability and strength
Solution Approach 2:
The patent creates a composite casting compound system that combines traditional cementitious materials with polymer additives. This composite formulation leverages the synergistic effects of different materials to achieve both high strength and sedimentation resistance simultaneously
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
This approach enables the production of aerated concrete moldings with improved compressive strength and reduced thermal conductivity, maintaining standard production parameters while avoiding sedimentation and corrosion issues, resulting in bulk densities from 240 to 260 kg/m³ and thermal conductivities from 0.068 to 0.072 W/mK.
Implementation Method 1
The use of aluminum sulfate has the disadvantage that it reacts strongly acidically in aqueous solution (pH value is approximately 3). This results in increased corrosion of the system technology. When the raw materials are dosed in certain sequences into the mixer, the acidic environment also causes carbonate-containing additives (e.g. limestone powder) to release CO 2 and the resulting foaming of the casting compound.
Implementation Method 2
A pourable mass, usually made from burnt lime as the CaO component, cement, quartz powder as the SiO 2 component, calcium sulfate and an aluminum component (blowing agent) and water, is mixed together
Implementation Method 3
The green cake is usually cut into shaped bodies and the shaped bodies are hardened in an autoclave.
Data Source
AI summary
Aerated concrete molded body (I) comprising calcium silicate hydrate bar framework, preferably a tobermorite bar framework, and pores, is claimed, where the aerated concrete molded body exhibits an A-number of above 1600, a thermal conductivity of = 0.085 W/mK and at least a compressive strength of 1.6 N/mm 2>. An independent claim is included for a process for producing (I) comprising preparing a casting compound from at least one calcium oxide component reacting in a hydrothermal process, preferably from burnt lime, at least a cement, at least a silica component reacting in hydrothermal process, preferably in the form of quartz powder, at least a calcium sulfate component and at least a blowing agent, especially in the form of an aluminum component, and water, binging the pourable mass poured into a mold to raise and stiffen into a green cake, cutting the cake into molded bodies and curing the molded body in an autoclave, where the casting compound contains an additive to prevent the sedimentation of castable solids that contain more than 50% of a finely divided silica-component with specific surface of 8000-30000 m 2>/g, as measured according to Blaine, and the water/solids value is 0.8-2.