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Send EmailMetakaolin, Meta Kaolin, Calcined Kaolin, 15123-81-6
| Parameter | Information |
|---|---|
| Product Name | Metakaolin |
| CAS Number | 15123-81-6 |
| Chemical Formula | Al₂O₇Si₂ (Metakaolinite) |
| Molecular Weight | ~222 g/mol |
| Definition | High-pozzolanic activity, fine particulate mineral admixture obtained by controlled calcination (600-900°C) of kaolinite mineral |
| Appearance | Grey – light brown powder |
| Odor | No characteristic mineral odor |
| Physical State (20°C) | Solid (powder) |
Metakaolin is formed by the thermal dehydroxylation of kaolinite (Al₂Si₂O₅(OH)₄). During calcination, the layered structure of kaolinite breaks down as hydroxyl groups (OH) are removed, resulting in an amorphous, highly reactive structure.
Reaction:
Kaolinite (Al₂Si₂O₅(OH)₄) → Metakaolin (Al₂O₇Si₂) + 2H₂O↑
(600-900°C) (Amorphous)
| Feature | Description |
|---|---|
| Crystal Structure | Initially layered structure of kaolinite becomes disordered (amorphous) after calcination |
| Specific Surface Area | 10 – 20 m²/g (measured by Blaine method) |
| Pozzolanic Activity | High; reacts with Ca(OH)₂ due to amorphous silica and alumina content |
| XRD Characteristics | Characteristic peaks of kaolinite disappear after calcination; amorphous halo is observed |
| Component | % (approx.) | Description |
|---|---|---|
| SiO₂ | 50 – 63 | Main component; primary source of pozzolanic activity |
| Al₂O₃ | 19 – 35 | High alumina content; enhances reactivity |
| Na₂O | 0.1 – 0.5 | Alkali content; may vary by source |
| CaO | 0.3 – 5 | Impurity; may indicate limestone residue in some ores |
| Fe₂O₃ | 0.1 – 1 | Color-imparting impurity; undesirable in light-colored products |
| K₂O | 1 – 2 | Alkali content; requires attention for ASR reactions |
| MgO | 0.1 – 2 | Impurity; generally low |
| TiO₂ | 0.1 – 0.5 | Impurity; source dependent |
| SO₃ | < 0.1 | Sulfate content; generally low |
| Loss on Ignition (LOI) | < 1.4 | Indicator of calcination completeness |
Note: Na₂O content may vary between different metakaolin sources. Typical metakaolin products generally contain 0.1-0.5% Na₂O. Please refer to the supplier's data for specific product specifications.
| Property | Value | Description |
|---|---|---|
| Mean Particle Size (D50) | ~8 – 10 µm | Finely ground; finer than cement |
| D10 (Particle Distribution) | ~1.8 µm | Very fine fraction |
| D90 (Particle Distribution) | ~23 µm | Coarser fraction |
| Bulk Density | 350 – 600 kg/m³ | Loose state; higher when compacted |
| Specific Gravity | ~2400 kg/m³ | True density |
| Moisture Content | < 0.1 % | Very low; depends on storage conditions |
| Color | Grey – light brown | Dependent on source and calcination temperature |
| Fineness (Blaine) | 800 – 1200 m²/kg | High specific surface compared to cement |
| pH (suspension) | 5.5 – 7.5 | Near neutral in aqueous environment |
| Thermal Conductivity | 0.1 – 0.2 W/mK | Low; suitable for insulation applications |
Metakaolin reacts with calcium hydroxide [Ca(OH)₂] formed during cement hydration to produce additional binding products. This reaction is known as the pozzolanic reaction.
General Reaction:
Metakaolin (SiO₂ + Al₂O₃) + Ca(OH)₂ + H₂O → C-S-H + C-A-H
(Calcium-Silicate-Hydrate)
(Calcium-Aluminate-Hydrate)
Reaction Stages:
| Stage | Description |
|---|---|
| 1. Hydration | Ca(OH)₂ is released during cement hydration |
| 2. Activation | Amorphous silica and alumina of metakaolin react with Ca(OH)₂ |
| 3. Binder Formation | C-S-H (calcium-silicate-hydrate) and C-A-H (calcium-aluminate-hydrate) phases are formed |
| 4. Densification | Secondary products improve pore structure |
| Test Method | Value | Description |
|---|---|---|
| ASTM C618 | Class N (Natural Pozzolan) | Metakaolin meets the criteria |
| Calcium Hydroxide Consumption | 1000 – 1500 mg Ca(OH)₂/g metakaolin | Indicates high activity |
| Lime Activity | > 1,000 psi (7 days) | Per ASTM C311 |
| Performance Parameter | Value | Description |
|---|---|---|
| Compressive Strength Increase (7 days) | 15 – 25% | Compared to cement-free reference |
| Compressive Strength Increase (28 days) | 20 – 30% | More pronounced in the long term |
| Flexural Strength Increase | 10 – 20% | Improved flexibility and tensile strength |
| Modulus of Elasticity | 5 – 15% increase | More rigid concrete |
| Performance Parameter | Value | Description |
|---|---|---|
| Sulfate Resistance | Significant improvement | 50-70% more resistant to sulfate attack |
| ASR Control (Alkali-Silica Reaction) | Severe expansion reduction | 70-90% reduction in ASR expansion |
| Chloride Diffusion | 60 – 80% lower permeability | Protection against reinforcement corrosion |
| Freeze-Thaw Resistance | 95 – 99% durability factor | Per ASTM C666 |
| Carbonation Resistance | Improved | Surface carbonation slows down |
| Abrasion Resistance | 15 – 25% increase | Improved surface hardness |
| Permeability (Chloride) | < 1000 Coulombs | ASTM C1202 (28 days) |
| Application | Function | Details |
|---|---|---|
| High Performance Concrete | Pozzolanic admixture | Improves strength, durability, and workability |
| Precast Concrete | Early strength enhancer | Used to achieve high strength at 7 days |
| Chemical Resistant Concrete | Sulfate and acid resistance | Wastewater treatment plants, sewer structures |
| Silica Fume Alternative | Economic alternative | Similar performance to silica fume at lower cost |
| White Cement | Color stabilization | Preferred in light-colored concretes |
| Marine Structures | Chloride permeability reduction | Durability in coastal and marine structures |
| Application | Function | Details |
|---|---|---|
| Repair Mortars | Strength enhancer | Structural repair and restoration |
| Plaster | Adhesion and strength | Improves surface quality |
| Adhesive Mortars | Bond strength | Ceramic and tile adhesives |
| Waterproofing Mortars | Impermeability | Sealing and water insulation |
| Self-Leveling Mortar | Flowability and strength | Floor screeds |
| Application | Function | Details |
|---|---|---|
| Geopolymer Production | Reactive binder | Alkali-activated metakaolin geopolymer synthesis |
| Cement-Free Binders | Carbon footprint reduction | Alternative to traditional cement |
| Impermeable Coatings | Surface protection | Chemical resistant coatings |
| Inorganic Polymers | High temperature resistance | Refractory applications |
| Application | Function | Details |
|---|---|---|
| Ceramic Plasticizer | Rheological modifier | Improves pressing and casting quality |
| Whitening Agent | Color lightening | Provides whiteness in ceramic bodies |
| Glaze Component | Matt and opaque effect | In ceramic glazes |
| Refractory Materials | Heat resistance | High temperature applications |
| Porcelain | Sintering aid | Densification and strength |
| Application | Function | Details |
|---|---|---|
| PVC Cable Sheaths | Acid scavenger and insulation additive | Improves electrical insulation |
| Polymer Composites | Filler and reinforcement | Improves mechanical properties |
| Thermoplastics | Melt flow modifier | Improves processability |
| Elastomers | Reinforcing filler | Improves hardness and abrasion resistance |
| Coatings | Barrier properties | Reduces gas and moisture permeability |
| Application | Function | Details |
|---|---|---|
| Pigment and Filler | Opacity and coverage | Improves paint quality |
| Anti-Corrosion Coatings | Barrier effect | Protection for metal surfaces |
| Fire Retardant Coatings | Heat barrier | Reduces flame spread |
| Powder Coatings | Flowability improvement | More uniform coating |
| Water-Based Paints | Viscosity modifier | Application ease |
| Application | Function | Details |
|---|---|---|
| Cement Sheaths | Sulfate resistance | Well cementing |
| Mud Stabilization | Rheological modifier | Drilling muds |
| Impermeable Barriers | Sealing | Underground storage |
| Application | Recommended Dosage | Description |
|---|---|---|
| Concrete Admixture | 5 – 15% by weight of cement | 10-15% for high durability; 5-10% for workability |
| Mortar Admixture | 10 – 20% by weight of cement | For repair mortars and adhesives |
| Geopolymer | 70 – 100% (as binder) | With alkali activator |
| Ceramics | 1 – 10% by weight | Depends on product type |
| PVC | 5 – 15% by weight | Cable sheath applications |
| Paint | 5 – 30% by weight | As filler and pigment |
| Parameter | Value | Description |
|---|---|---|
| Water/Cement Ratio Increase | +2 – 5% | Water demand increases with metakaolin use |
| Superplasticizer Requirement | Recommended | Workability maintained with superplasticizer |
| Slump Loss | 5 – 15% | Workability time may shorten |
| Concrete Density | +1 – 3% | More dense concrete |
| Standard | Description |
|---|---|
| ASTM C618 | Meets Class N (Natural Pozzolan) or Class F (Fly Ash) requirements |
| ASTM C1709 | Standard specification for metakaolin |
| EN 450 | Similar to fly ash standards |
| EN 13263 | Similar performance to silica fume |
| TS 25 | Turkish Cement Standard (as pozzolanic admixture) |
| ASTM C311 | Test methods for pozzolanic activity |
| Parameter | Information |
|---|---|
| Packaging Options | 15 kg kraft bags, 40 lb bags, 450-2000 kg big-bags |
| Storage Conditions | Store in a dry, cool place away from direct sunlight in original packaging |
| Shelf Life | 24 months under proper conditions; must be kept away from moisture |
| Moisture Sensitivity | High; should be used promptly after opening |
| Caking | May cake in humid environments; sieving recommended before use |
| Parameter | Information |
|---|---|
| Acute Oral Toxicity (LD50) | > 5,000 mg/kg (low toxicity) |
| Skin Irritation | Mild irritant; prolonged contact should be avoided |
| Eye Irritation | Mild irritant; dust contact may cause mechanical irritation |
| Inhalation | Dust inhalation may cause respiratory tract irritation; long-term exposure carries silicosis risk |
| Carcinogenicity | Not classified as a carcinogen |
| Water Solubility | Insoluble; disperses in water |
| WGK Germany | 1 (low hazard to water) |
| Hazard Class | Category | H-Statement |
|---|---|---|
| Serious Eye Damage | Category 2 | H319: Causes serious eye irritation |
| Specific Target Organ Toxicity (Single Exposure) | Category 3 | H335: May cause respiratory irritation |
Signal Word: WARNING
Hazard Pictograms: GHS07 (Exclamation Mark)
Hazard Statements (H-Codes):
| Code | Statement |
|---|---|
| H319 | Causes serious eye irritation |
| H335 | May cause respiratory irritation |
| Code | Statement |
|---|---|
| P261 | Avoid breathing dust/fume/gas/mist/vapors/spray |
| P264 | Wash hands thoroughly after handling |
| P271 | Use only outdoors or in a well-ventilated area |
| P280 | Wear protective gloves/protective clothing/eye protection/face protection |
| P304+P340 | IF INHALED: Remove person to fresh air and keep comfortable for breathing |
| P305+P351+P338 | IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses if present |
| P337+P313 | If eye irritation persists: Get medical advice/attention |
| P501 | Dispose of contents/container in accordance with local regulations |
| Route of Exposure | Action to Be Taken |
|---|---|
| Inhalation | Move to fresh air. If breathing difficulty occurs, administer oxygen. If symptoms persist, seek medical attention |
| Skin Contact | Wash with plenty of soap and water. Remove contaminated clothing. If irritation develops, seek medical attention |
| Eye Contact | Rinse immediately with plenty of water for at least 15 minutes. Keep eyelids open. If irritation persists, seek medical attention |
| Ingestion | Rinse mouth. If conscious, drink water. Do not induce vomiting. Seek medical attention |
| Parameter | Information |
|---|---|
| Flash Point | Not applicable (not flammable) |
| Autoignition | Not applicable |
| Explosive Properties | Not explosive |
| Oxidizing Properties | Not oxidizing |
| Fire Extinguishing | Use extinguishing media appropriate to surrounding environment |
| Parameter | Information |
|---|---|
| Aquatic Toxicity | Low toxicity; large quantities may have physical effects |
| Biodegradability | Not biodegradable (mineral) |
| Bioaccumulation | Not expected |
| Environmental Precautions | Prevent dry material from entering soil or water |
| WGK Germany | 1 (low hazard to water) |
| Region / Authority | Status |
|---|---|
| USA (FDA) | Suitable for use in food contact materials |
| European Union (REACH) | Registered |
| Turkey (KKDIK) | Compliance required |
| OSHA | Regulated as dust (respiratory irritation) |
| Property | Metakaolin | Silica Fume | Fly Ash (Class F) | Cement (Portland) |
|---|---|---|---|---|
| Specific Surface (m²/kg) | 800-1200 | 15,000-30,000 | 300-600 | 300-400 |
| Pozzolanic Activity | High | Very High | Moderate-High | - |
| Water Demand | Moderate | High | Low | Baseline |
| Early Strength | High | Very High | Low-Moderate | Baseline |
| Sulfate Resistance | High | High | Moderate | Low |
| ASR Control | High | High | Moderate | Low |
| Permeability | Very Low | Very Low | Low | High |
| Cost | Moderate | High | Low | Baseline |
Q1: What is metakaolin?
A: Metakaolin is a finely powdered mineral admixture with high pozzolanic activity, obtained by calcining kaolinite mineral (Al₂Si₂O₅(OH)₄) at 600-900°C.
Q2: What is metakaolin's role in cement?
A: Metakaolin reacts with calcium hydroxide [Ca(OH)₂] formed during cement hydration to produce additional C-S-H (calcium-silicate-hydrate). This increases concrete strength, durability, and impermeability.
Q3: What is the difference between metakaolin and silica fume?
A: Silica fume has higher specific surface area (>15,000 m²/kg) and higher pozzolanic activity. However, metakaolin is more economical, has lower water demand, and is advantageous in terms of color (suitable for lighter colored concretes).
Q4: What proportions should metakaolin be used in?
A: 5-15% by weight of cement. 10-15% is preferred for high durability applications, and 5-10% for workability-focused applications.
Q5: How does metakaolin affect water demand?
A: Due to its high specific surface area, metakaolin increases water demand by 2-5%. Therefore, the use of superplasticizer is recommended to maintain workability.
Q6: Which standards does metakaolin comply with?
A: Metakaolin can be used in compliance with ASTM C618 (Class N), ASTM C1709, EN 450, and TS 25 standards.
Q7: What is the shelf life of metakaolin?
A: It is stable for 12 months in its original packaging under proper storage conditions (dry, cool, away from direct sunlight). Once opened, it should be used promptly to prevent moisture absorption.
Q8: Is metakaolin safe?
A: Metakaolin is a mineral admixture with low toxicity. However, inhalation of dust may cause respiratory tract irritation. Use of dust mask, protective goggles, and gloves is recommended during use.
| Property | Value |
|---|---|
| CAS Number | 15123-81-6 |
| Chemical Formula | Al₂O₇Si₂ |
| Molecular Weight | ~222 g/mol |
| Appearance | Grey – light brown powder |
| Mean Particle Size (D50) | ~8-10 µm |
| Specific Gravity | ~2400 kg/m³ |
| Bulk Density | 350-600 kg/m³ |
| Moisture Content | < 0.1% |
| Specific Surface (Blaine) | 800-1200 m²/kg |
| Pozzolanic Activity (7 days) | > 1,000 psi |
| Main Components | SiO₂ (50-63%), Al₂O₃ (19-35%) |
| Loss on Ignition (LOI) | < 1.4% |
| Color | Grey – light brown |
| Shelf Life | 24 months (under proper storage) |
| GHS Signal Word | WARNING |
| UN Number | Not applicable |
| WGK Germany | 1 (low hazard to water) |
Moisture Sensitivity: Metakaolin is sensitive to moisture. Caking and activity loss may occur if the packaging is opened and exposed to moisture. Opened packages should be used immediately or stored in moisture-proof containers.
Dust Control: Metakaolin is a fine particulate material. Inhalation of dust may cause respiratory tract irritation. Long-term exposure carries silicosis risk. Use a dust mask (N95/FFP2) during handling.
Water Demand: Metakaolin increases water demand due to its high specific surface area. Use of superplasticizer is recommended to maintain workability.
Dosage Optimization: Recommended dosages (5-15%) are starting points. Optimum dosage for each application should be determined through trial mixes. Overdosing may cause workability issues and economic inefficiency.
Setting Time: Metakaolin may affect the setting time of cement. Shortening or lengthening of setting time may occur, especially at high dosages (≥10%). This should be monitored through trial mixes.
Color Effect: Metakaolin imparts a light grey-brown color to concrete. Should be used with caution in white or light-colored concretes.
Concrete Applications:
Metakaolin should be mixed dry with cement or added separately to the concrete mixer
Use with superplasticizer to maintain workability
Water/cement ratio should be optimized
Concrete curing should be given care (at least 7 days)
Storage:
Store in a dry, cool, well-ventilated place
Protect from direct sunlight and moisture
Keep tightly closed in original packaging
Opened packages should be used promptly
Handling:
Use dust mask (N95/FFP2), protective goggles, and gloves
Avoid dust formation
Use in well-ventilated areas
Wash hands after handling
Testing:
Conduct trial mixes before application
Determine optimum dosage
Check setting time and workability
Adjust superplasticizer amount if needed
This Technical Data Sheet (TDS) is for informational purposes only and is prepared based on available technical data. The user is solely responsible for determining the suitability of the product for their specific application and for complying with all local, national, and international regulations. For complete safety, storage, handling, transport, waste, and regulatory compliance information, the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier must be consulted. This document does not substitute professional advice. Dosage and application conditions should be optimized through product-specific trials. Chemical composition values are average values and may vary by product grade/quality. Na₂O content may vary by source; please check the supplier's data.