Aluminium Paste & Powder for AAC

Aluminium Paste & Powder (APP) is a key aerating agent for producing lightweight aerated concrete. It reacts with alkaline substances to release hydrogen, creating a porous structure that enhances thermal insulation, soundproofing, and construction flexibility. Ideal for reducing building weight and improving earthquake resistance.

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Aluminium Paste & Powder for AAC

Aluminium Paste & Powder (APP) is a crucial aerating agent in producing AAC blocks. It reacts with alkaline substances to release hydrogen gas, forming a lightweight, porous structure. Below are the key aspects:

1. Function & Reaction Mechanism

1.1 Aeration Principle

In an alkaline environment (e.g., Ca(OH)₂), Aluminium Paste & Powder reacts with water to produce hydrogen gas:

2آل+3Ca(OH)2+6H2O3ثاني أكسيد الكالسيومآل2O36H2O+3H2

This reaction creates uniformly distributed pores within the slurry, reducing the final product density to 500-700 kg/m³—only one-fifth of conventional concrete.

1.2 Pore Structure Impact

The size and distribution of pores directly determine AAC’s insulation and soundproofing properties. To achieve an ideal pore structure, the aluminum particles must have a suitable fineness (≤3% residue on a 0.075mm sieve) and a high active aluminum content (≥85%).

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2. Production Process & Technical Requirements

The production process of aerated aluminum paste (slurry)/powder is crucial in determining the final product’s quality and performance. This chapter will detail the production flow, key technologies, and control points of each stage in the manufacturing process of aerated aluminum paste (slurry)/powder to help readers better understand the manufacturing of this critical material.

2.1 Production Flow

The production flow of aerated aluminum paste (slurry)/powder typically includes the following main steps:

2.1.1 Raw Material Preparation

Before production begins, the selection and Preparation of raw materials are crucial. The main raw materials include aluminum powder, additives (such as DEG, dispersants, etc.), and other ingredients. The selection of aluminum powder is usually based on its particle size, activity, and purity. Highly active aluminum powder can generate more hydrogen gas when reacting with water, thus achieving better gas generation effects. The selection of additives needs to consider their role in the aerated aluminum paste, such as improving fluidity and enhancing reactivity.

2.1.2 Mixing

The prepared aluminum powder and additives are mixed in a certain proportion. This step usually uses high-efficiency mixing equipment to ensure uniform component distribution and avoid agglomeration. The mixing time and speed must be strictly controlled during the mixing process to ensure a sufficient combination of aluminum powder and additives, laying a good foundation for subsequent reactions.

2.1.3 Grinding and Classification

The mixed materials need to be ground to reach the specified particle size. This step is crucial for improving the activity of the aluminum powder. Using ball mills or other types of grinding equipment can effectively reduce the particle size and increase the surface area of the aluminum powder, thereby enhancing its reactivity with water. After grinding, the materials must also be classified to ensure particle size and product distribution consistency.

2.1.4 Paste Preparation

In this step, the ground aluminum powder is mixed with water and other necessary additives to form the aluminum paste. The reaction conditions at this time (such as temperature and stirring speed) need to be controlled to ensure that the reaction between aluminum powder and water is sufficient to generate a stable bubble structure. Better gas generation effect and fluidity can be obtained through reasonable proportioning and stirring.

2.1.5 Storage and Packaging

The prepared aerated aluminum paste (slurry) must pay attention to environmental conditions during storage and transportation, avoiding high temperatures and humidity to prevent premature reaction and failure. Its physical and chemical properties should be checked regularly during storage to ensure stable product quality. Finally, the aluminum paste must be packaged according to standards to ensure no leakage or deterioration occurs during transportation.

2.2 Key Technologies

In the production process of aerated aluminum paste (slurry)/powder, several key technologies have a profound impact on the performance and quality of the final product:

2.2.1 Ball Milling Technology

Ball milling is an important technology for grinding aluminum powder. The physical grinding process can effectively reduce the particle size of the aluminum powder and increase its specific surface area. Smaller particle sizes help enhance the reactivity of the aluminum powder, allowing it to generate hydrogen gas more rapidly when reacting with water, thereby forming a uniform and stable bubble structure.

2.2.2 Classification Technology

Classification technology plays an important role in ensuring the consistency of the particle size distribution of aluminum powder. Through classification, aluminum powders of different particle sizes can be separated, improving the activity and adaptability of the material. A suitable particle size distribution can optimize bubble formation and enhance aerated concrete’s strength and thermal insulation performance.

2.2.3 Reaction Control Technology

In the preparation process of aluminum paste, controlling reaction conditions (such as temperature and time) is crucial. Reasonable reaction conditions can ensure that the reaction between aluminum powder and water is sufficient to generate an adequate number of evenly distributed bubbles. The application of reaction control technology helps to improve the stability and consistency of the product.

2.2.4 Formulation Optimization Technology

Product performance can be improved by continuously optimizing the formulation of aluminum paste (slurry). For example, adding appropriate amounts of certain additives can increase the aluminum powder’s reaction rate and improve the aluminum paste’s fluidity and stability. In addition, for different application needs, enterprises can develop various types of aluminum paste to meet the market’s diverse needs.

2.2.5 Environmental Control Technology

In production, controlling environmental conditions (such as temperature and humidity) is also crucial to ensure product quality. Especially in the storage and transportation stages, it is necessary to provide suitable environmental conditions to prevent the aluminum paste from failing or deteriorating due to environmental changes.

2.3 Quality Control

Quality control is an important link throughout the production process to ensure the stable performance of aerated aluminum paste (slurry)/powder. Enterprises usually establish a complete quality management system, including:

2.3.1 Raw Material Inspection

Before production begins, all raw materials must undergo strict quality inspection to ensure they meet production standards. The aluminum powder’s activity, purity, and particle size distribution need to be tested to determine whether it meets the production requirements.

2.3.2 Process Monitoring

During the production process, the parameters of each stage (such as temperature, humidity, mixing time, etc.) are monitored in real-time to ensure that the production process is always in the best state. In addition, online testing equipment can detect and adjust problems in time to prevent the generation of unqualified products.

2.3.3 Finished Product Inspection

After the product is produced, comprehensive performance testing of the finished product is required, including indicators such as fluidity, gas generation, and compressive strength, to ensure that it meets relevant standards and customer needs. Only products that have passed strict testing can be put on the market for sale.

3. Application Advantages & Market Trends

3.1 Comparison Between Aluminum Paste and Traditional Dry Aluminum Powder

CharacteristicAluminum Paste (Water-based)Dry Aluminum Powder
عملية الإنتاجWet grinding, no need for degreasingDry grinding, requires degreasing
السلامةNo dust explosion riskFlammable and explosive, requires nitrogen protection
سهولة الاستخدامDirectly added to slurry, good dispersionRequires pre-degreasing treatment
Environmental ImpactLow pollution, easy wastewater treatmentHigh energy consumption, more pollution

3.2 Performance Advantages

  • Lightweight & High Strength: Reduces building weight by over 40%, enhancing earthquake resistance.
  • Thermal Insulation: Thermal conductivity ranges from 0.11 to 0.16 W/m·K, outperforming traditional brick walls.
  • Ease of Construction: The material can be cut and drilled, allowing for flexible applications in complex structures.

3.3 Market Trends

  • Price Fluctuations: Aluminium prices and energy costs influence market pricing, which will average around ¥10,000 per ton in 2024.
  • Regional Supply & Demand: Major production areas include Anhui, Shandong, and Jiangsu, while demand in the southwest region is growing significantly.
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4. Quality Control & Testing Methods

Below are key testing methods and technical requirements based on industry standards and practical applications:

4.1 Key Physical Property Tests

4.1.1 Active Aluminium Content Measurement

  • Principle: Hydrogen gas volume from the reaction between Aluminium Paste & Powder and an alkaline solution determines the active aluminum content (theoretical aeration capacity: 1.24 L/g).
  • Method: Operators follow JC/T407 standards using a gas evolution apparatus (featuring reaction bottles, gas volume tubes, and thermostatic baths). The hydrogen gas volume is recorded and adjusted based on temperature and pressure to calculate active aluminum content.
  • Standard: Oil-based aluminum paste must have an active aluminum content of ≥90%, while water-based aluminum paste must be ≥85%.

4.1.2 Fineness Testing

  • Sieving Method: Dried aluminum powder is sieved using a 0.075mm copper mesh (wet sieving with a dispersing agent), with a residue requirement of ≤3%.
  • Laser Particle Analysis: Used to verify uniform particle distribution and optimize milling processes.

4.1.3 Solid Content Measurement

  • Procedure: Weigh aluminum paste samples, dry at 105°C until constant weight, and calculate solid content. (Oil-based ≥75%, water-based ≥65%).

4.2 Chemical Performance Tests

4.2.1 Gas Evolution Characteristics

  • Gas Evolution Curve Test: Conducted at 45°C, where Aluminium Paste & Powder reacts with a cement-sodium hydroxide mixture. The gas evolution curve ensures synchrony between aeration and slurry thickening, preventing collapse or trapped gas.
  • Standard: Oil-based aluminum paste should achieve ≥50% gas evolution in 4 minutes, ≥80% in 16 minutes, and ≥90% in 30 minutes.

4.2.2 Hydrogen Evolution Test (for Passivated Aluminium Powder)

  • pH Monitoring Method: Aluminium powder is dispersed in water and heated to 60°C while monitoring pH changes. A drop to 4.19-4.23 within 35 minutes indicates excessive hydrogen evolution (failure), while a stable pH of 6-7 confirms passivation integrity.

4.2.3 Oxidation Degree Testing

  • Oxygen-Nitrogen Analyzer Method: Pre-treated Aluminium Paste & Powder are heated in a dual-layer graphite crucible (4.5kW), measuring released oxygen to evaluate oxide layer thickness and sintering quality.

4.3 Safety & Environmental Standards

4.3.1 Explosion Prevention

  • Dust Concentration Control: Maintain aluminum powder concentration below 10g/m³ to mitigate explosion risks.
  • Electrostatic Protection: Wet-process aluminum paste is preferred over dry powder to reduce dust explosion hazards.

4.3.2 Environmental Compliance

  • Wastewater Treatment: Monitor heavy metal content (e.g., aluminum ions) in wet milling effluents to ensure regulatory compliance.

4.4 Equipment & Standards Reference

  • Key Equipment: Laser particle analyzers, gas evolution measurement devices, oxygen-nitrogen analyzers, thermal gravimetric analyzers, precision pH meters.
    • Applicable Standards: JC/T407-2008: Aluminium paste technical specifications (active aluminum content, fineness, aeration rate).
    • GB/T11968-2023: Testing methods for autoclaved aerated concrete blocks.

4.5 Important Considerations

  • Sample Pre-Treatment: Before testing, remove oil contamination from aluminum powder via ultrasonic cleaning with petroleum ether, followed by drying.
  • Process Adaptation: Adjust the dosage of Aluminium Paste and powder based on slurry temperature and calcium-to-silicon ratio (0.55-0.80) to synchronize aeration with thickening.
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5. Impact of Gas Evolution Characteristics on AAC

5.1 Aeration Speed & Production Process Synchronization

5.1.1 Matching Aeration & Thickening

Aluminium Paste & Powder must aerate at a rate that aligns with slurry thickening:

  • Too Fast (e.g., >20ml in 2 minutes): Excessive gas release before slurry setting causes pore merging, collapse, or sedimentation.
  • Too Slow (e.g., <6ml in 2 minutes): Residual aluminum powder continues reacting after the slurry sets, leading to trapped gas, cracks, or uneven expansion.
  • Ideal Range: Data suggests optimal stability at 6-15ml in 2 minutes, 40-60ml in 8 minutes, and 70-90ml in 16 minutes.

5.1.2 Temperature Sensitivity

Maintain slurry temperature at 40-60°C. Excessive heat accelerates aeration, risking uncontrolled expansion, while low temperatures slow aeration, leading to uneven pore distribution.

5.2 Gas Evolution & Pore Structure

  • Pore Uniformity: High active aluminum content (≥85%) and fine particle size (≤3% residue on a 0.075mm sieve) ensure even aeration. Low activity or oversized particles create large, interconnected pores, reducing compressive strength by 15-30%.
    • Density & Functional Properties: Theoretical Gas Evolution: 1g of aluminum produces 1.24L hydrogen. Practical aeration should reach at least 90% of the theoretical value to ensure a 500-700 kg/m³ density.
    • Thermal & Acoustic Performance: When pore size ranges from 0.2-2mm and porosity is 70-85%, thermal conductivity drops to 0.11-0.16W/m·K, outperforming conventional brick walls by 4-5 times.

6. Optimization Strategies for Aeration Performance

6.1 Raw Material Selection

  • Prefer Water-Based Aluminium Paste (GLS-65): It offers better dispersion and minimizes dust explosion risks.
  • Active Aluminium Content Testing: For accurate results, utilize JC/T407 gas evolution measurement devices with temperature compensation.

6.2 Process Adjustments

  • Calcium-Silicon Ratio (0.55-0.80): Excessive alkalinity (high Ca(OH)₂ content) inhibits aluminum reactions.
  • Foam Stabilizers (e.g., Soluble Oil): Extend bubble stability by 30-50%, reducing collapse risks.

Fiver Star New Materials ensures optimal concrete quality, enhancing thermal efficiency, mechanical strength, and construction adaptability by fine-tuning aeration parameters.

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Specification of Aluminium Paste & Powder for AAC

Product Name Solid Content (%) Active Alumina (%) Bulk Density Median Particle Size (D₅₀) Suitable for AAC
DEG-60 70% ≥96 0.15 58–62 <600
DEG-40 70% ≥94 0.15 36–42 <500
DEG-35 70% ≥94 0.15 33–35 <400
DEG-25 70% ≥94 0.15 25–27 <400
DEG-18 70% ≥92 0.11 17–19 <350

 

Estimated Cost of Aluminium Paste & Powder for AAC

We suggest you to communicate with us fully before purchasing, we will certainly consider all aspects and provide a fair and reasonable price plan. By choosing us, you will get the best product and the best value for your money.

Choosing Right Specification

Choosing the right size of product gives you the best value for money. Our Metal Flash Aluminum Silver Paste is available in a wide range of particle sizes and purities, with prices varying by specification. By communicating your needs in detail and choosing the right size, you can get the best value for your money.

Purchasing Quatity

The larger the quantity purchased, the lower the unit price will be. Bulk orders allow us to better share our production and operating costs, so we are happy to offer discounted prices for bulk purchases.

Payment Terms

The timing and method of payment you choose will also affect the price. For example, paying in full upfront can result in a more favourable price, as it reduces our cost of capital. Please discuss the most suitable payment option with our sales team.

النقل والمواصلات

Transport and logistics are also factors that affect the total cost of ownership. Different modes of transport and destinations will incur different shipping costs. Duties, insurance and other costs also need to be taken into account. By calculating these factors in advance of purchase, you can more accurately estimate the total cost.

Manufacturing Craft of Aluminium Paste & Powder for AAC

At Five Star Materials, our Aluminium Paste & Powder for AAC produced in a delicate and rigorous process. Below is our basic production process:

Raw Material Preparation

We purchase high purity raw materials from trusted suppliers to ensure the quality of our products from the source.

Crushing

The raw material is crushed to convert the aluminium blocks into tiny particles for subsequent processing.

Mixing Process

The crushed aluminium powder is mixed with our specially formulated solvents and additives and then blended through a high speed mixing process. This step is very important as it determines the stability of the aluminium paste and the shape of the particles.

Filtration and testing

After grinding, the aluminium paste is passed through a filtration system to remove possible impurities. Our quality control team will then carry out a series of tests on the product, such as particle size, gloss, metallic feel, etc., to confirm that the product meets our high quality standards.

التعبئة والتغليف والتخزين

Products that have passed rigorous testing are carefully packaged and then stored in our warehouses, ready for shipment to our customers.

Please note that this is a basic production process and the exact process may vary depending on the specific requirements of the product. At Five Star Materials, we take quality control very seriously and ensure that our products meet our strict quality standards at every step of the production process.

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At Five Star Material, we understand that every project is unique, and our goal is to provide the best customized solutions for each customer.

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