Bột silicon kỵ nước dùng cho vữa chống thấm: Cơ chế hoạt động, liều lượng và ứng dụng

Bột silicon kỵ nước là gì?

According to the Michem product page, Silicone Hydrophobic Powder is:

“A free-flowing powder additive based on silicone compounds and specially processed carriers. It is designed to be easily mixed into dry powder formulations and, once added to cement- or gypsum-based systems, provides excellent hydrophobic properties after curing.”

The key distinction from liquid water repellents is the powder format. In dry-mix mortar production — where all ingredients are pre-blended at the factory and only water is added on site — a powder additive is essential. Liquid water repellents cannot be pre-mixed into dry formulations without special equipment and stability concerns.

Michem Silicone Hydrophobic Powder: Verified Technical Specifications

Tất cả dữ liệu dưới đây được trích dẫn trực tiếp từ Michem product page.

Thông số kỹ thuật

Nguồn: michemicals.com

Important Note on Dosage

The product page includes an explicit caution:

“The exact dosage should be determined through laboratory and production testing according to raw materials, target water repellency, and formula design.”

This means the 0.1–1.0% range is a starting point, not a fixed recommendation. The optimal dosage depends on:

• The cement or gypsum type in the formulation
• The target level of water absorption reduction
• Other additives present in the mix
• The specific application (e.g., waterproofing mortar requires higher dosage than standard grout)

Cơ chế hoạt động của bột silicon kỵ nước

The Michem product page provides a clear explanation of the mechanism:

Step 1: Dispersion in Dry Mix

The powder is evenly dispersed throughout the dry-mix formulation during factory blending. Because it is a free-flowing powder, it mixes uniformly with cement, sand, and other dry additives without clumping or segregation.

Step 2: Integration During Mixing

“After being evenly dispersed in the dry mix formula and mixed with water on site, Silicone Hydrophobic Powder becomes integrated into the mortar or plaster matrix.”

When the dry mix is combined with water on site, the silicone hydrophobic component is released from its carrier and begins to disperse throughout the wet mortar.

Step 3: Hydrophobic Barrier Formation During Curing

“During curing, the active silicone component distributes through the capillary network and forms a hydrophobic barrier on internal pore surfaces.”

As the mortar cures, the active silicone compound migrates through the capillary pore structure of the hardened material. It bonds to the pore surfaces, creating a water-repellent molecular film.

The Chemistry: Siloxane Bonding

The product page explains the molecular mechanism:

“Silicone hydrophobic powder forms a low-surface-energy, water-repellent molecular film on substrates through siloxane bonding, effectively repelling liquid water by reducing surface wettability.”

Siloxane bonds (Si-O-Si) are chemically stable and durable. Unlike surface-applied water repellents that can wear off or degrade, the internal hydrophobic barrier formed by silicone hydrophobic powder is integrated into the material structure, providing long-term water repellency.

Key Mechanism Advantage

“Because it works within the material structure rather than only on the surface, it can provide durable internal water repellency.”

This is a critical distinction. Surface treatments (spray-on water repellents) protect only the outer layer. If the surface is damaged, worn, or cracked, water penetration resumes. Integral hydrophobic treatment with silicone powder protects the entire material volume.

Key Benefits

The Michem product page identifies six key benefits of Silicone Hydrophobic Powder:

1. Excellent Water Repellency

“The main benefit is its ability to significantly reduce water absorption in mortar, plaster, grout, and other building materials. This helps keep surfaces and structures drier over time.”

2. Protection Against Moisture Damage

“By reducing water penetration, the product helps protect building materials from moisture-related damage such as freeze-thaw deterioration, efflorescence, cracking, and mold risk.”

3. Ideal for Water-Critical Applications

“This additive is especially useful for exterior wall systems, façade mortars, insulation systems, and humid-area construction where water resistance is critical.”

4. Easy Integration into Dry Mix

“Because it is in powder form, the product can be directly incorporated into dry mix mortar formulations without requiring special liquid dosing equipment.”

5. Maintained Vapor Permeability

“While improving hydrophobic performance, the product can still allow construction materials to retain reasonable vapor permeability, depending on the formula design.”

This is an important distinction from waterproof membranes. A completely impermeable barrier traps moisture inside the wall, leading to blistering and delamination. Silicone hydrophobic powder repels liquid water while allowing water vapor to escape — a “breathable” waterproofing approach.

6. Cost-Effective Performance

“A relatively low dosage can deliver a clear improvement in water resistance, making Silicone Hydrophobic Powder a practical additive for higher-value mortar products.”

At 0.1–1.0% dosage, the cost impact on the total formulation is modest, while the performance improvement in water resistance is significant.

Lĩnh vực ứng dụng

The Michem product page confirms six main application areas:

1. Waterproof Mortar

“In waterproof mortar formulations, Silicone Hydrophobic Powder helps reduce capillary water absorption and improve the overall waterproofing performance of the hardened material.”

This is the primary application — cement-based waterproofing mortars used in basements, water tanks, swimming pools, and below-grade structures.

2. Exterior Plaster and Façade Mortars

“For exterior plaster and façade mortars, the product helps resist rainwater penetration and improve weather durability.”

Façade mortars are constantly exposed to wind-driven rain. Without hydrophobic treatment, the porous mortar absorbs water, leading to staining, efflorescence, and freeze-thaw damage in cold climates.

3. Tile Grout

“In tile grout applications, it reduces water uptake and helps maintain grout durability in wet environments such as bathrooms, kitchens, and exterior tiled surfaces.”

Tile grout is particularly vulnerable to water absorption because of its high cement content and fine aggregate. Hydrophobic treatment prevents water from penetrating behind tiles, reducing the risk of mold growth and substrate damage.

4. Wall Putty and Finishing Materials

“It can be used in wall finishing materials where moderate water repellency and moisture resistance are required.”

Wall putties and skim coats benefit from hydrophobic treatment to prevent moisture from penetrating through the finish layer into the substrate.

5. Gypsum Plasters and Gypsum-Based Products

“In selected gypsum plasters and gypsum-based dry mix products, silicone hydrophobic powder helps reduce sensitivity to moisture and improve service performance.”

Gypsum is naturally more water-sensitive than cement. Hydrophobic powder helps gypsum products maintain performance in humid environments where they would otherwise soften and degrade.

6. External Insulation Finishing Systems (EIFS)

“In external insulation finishing systems, this additive helps improve water resistance while supporting the durability of the façade system.”

EIFS systems are multi-layer assemblies where water penetration can cause insulation degradation and system failure. Hydrophobic treatment of the base coat and finish mortar provides critical protection.

Powder vs Liquid Water Repellents

The Michem product page provides a comparison explaining why powder-form hydrophobic additives are preferred for dry-mix applications:

“For dry mortar factories, this makes powder-type hydrophobic additives a highly efficient choice.”

Nguồn: michemicals.com

Dosage Guidance

Starting Dosage Recommendations

The product page specifies a dosage range of 0,1%–1,0% of the total dry mix formulation. Based on the application areas described on the page, the following starting points are consistent with the product’s intended use:

Lưu ý quan trọng: These starting points are based on the product’s stated dosage range (0.1–1.0%) and application descriptions from the product page. The exact dosage must be determined through laboratory testing with your specific raw materials and performance targets.

Testing Protocol

To determine the optimal dosage for your formulation:

1. Prepare test batches at 3–4 dosage levels within the 0.1–1.0% range
2. Measure water absorption per EN 1062-3 or ASTM C1403 (or your local standard)
3. Test vapor permeability to ensure the “breathable” property is maintained
4. Verify compatibility with other additives in the formulation (RDP, cellulose ether, PCE)
5. Conduct accelerated weathering to confirm long-term performance

Compatibility Considerations

The product page notes that Silicone Hydrophobic Powder is “dispersible in dry mix systems,” confirming its compatibility with standard dry-mix production. However, formulators should verify compatibility with:

• Ete cellulose (HPMC, MHEC, HEC, CMC) — these provide water retention; the hydrophobic powder reduces water absorption. Both functions are complementary, not contradictory.
• Bột polymer có thể tái phân tán (RDP) — provides flexibility and adhesion; hydrophobic powder provides water repellency. Both can coexist in the same formulation.
• Superplasticizers (PCE) — controls water demand; no known incompatibility with silicone-based hydrophobic agents.
• Canxi formiat — accelerator; no known interaction with hydrophobic agents.

As with any additive combination, laboratory testing is essential to confirm that all components perform as expected in the final formulation.

Tại sao nên chọn bột silicone kỵ nước Michem?

The product page identifies the target customer base:

“Whether you are a dry mix mortar factory, tile grout producer, wall putty manufacturer, waterproofing material distributor, or construction chemical importer”

Michem cung cấp:

• Complete technical support for international customers
• Mẫu thử miễn phí for product evaluation
• TDS, SDS, and COA documentation
• Mẫu hàng sẽ được gửi đi trong vòng 48 giờ, kèm theo các báo cáo so sánh độ ổn định của các lô sản phẩm
• Customized solutions based on your formulation system