Code of practice for the application of silicone-based water repellents
1987 Edition

Scope of Practice (Clause 1.1):

This specification details the procedures for preparing and treating concrete and masonry surfaces using silicone-based water repellents to protect against water ingress and related deterioration.

Highlights:

• Emphasis on thorough surface preparation.
• Approved application methods for silicone repellents.
• Safety advisory: Avoid masks that increase solvent vapor retention; in confined environments, use airline respirators (Clause 6.3).

Standard Units & Definitions (SI System):

Process Flow Diagram

flowchart TD
    A[Surface Preparation] --> B[Silicone Repellent Application]
    B --> C[Drying and Curing]
    C --> D[Inspection and Quality Assurance]

The standard ensures efficient water repellency through correct surface treatment and safe repellent application.

Fundamental Details (Clauses 1.1 & 3.2.1):

• Addresses surface preparation and application processes for silicone-based water repellents.
• Repellents of Class A or B are diluted with mineral spirit or xylene.

Mineral Spirit Specifications (Clause 3.2.1):

Recommended solid content is at least 5%, although 3% may be acceptable.

Units & Definitions (SI Units):

Safety Advisory (Clause 6.3):

• Do not use masks that retain solvent vapors.
• Use airline respirators in enclosed areas.

flowchart LR
    A[Surface Prep] --> B[Dilution with Mineral Spirit/Xylene]
    B --> C[Verify Mineral Spirit Parameters]
    C --> D[Apply Water Repellent (≥5% solids)]
    D --> E[Implement Safety Measures]

This ensures adherence to preparation, application, and safety norms as per IS 12054.

Classification of Silicone Water Repellents (Clause 3.1.1):

Note: If substrate type is uncertain, default to Class B.

Preparation Guidelines (Clause 3.2.1):

• Classes A and B are diluted with mineral spirit or xylene.
• Mineral spirit must conform to:
  • Minimum flash point: 27°C
  • Boiling range: 135-185°C
  • Minimum Kauri-Butanol value: 34

• Solid content should be at least 5% for optimal efficiency, though 3% may suffice.

Preparation Formula:

[ Water Repellent = Class A or B Material + Mineral Spirit/Xylene (Diluent) ]

Maintain solids concentration ≥ 5% to ensure performance.

flowchart TD
    A[Identify Surface Type] -->|Siliceous| B[Use Class A]
    A -->|Calcareous| C[Use Class B or G]
    B --> D[Prepare Dilution]
    C --> D
    D --> E[Apply Mineral Spirit/Xylene]
    E --> F[Check Flash Point ≥ 27°C]
    E --> G[Check Boiling Range 135-185°C]
    E --> H[Check Kauri-Butanol ≥ 34]
    F & G & H --> I[Ensure ≥ 5% Solids]
    I --> J[Apply Water Repellent]

Summary: Choose repellent class based on substrate, dilute with specified solvents, and maintain recommended solids concentration.

Testing Procedure for Selecting Suitable Repellent Class (Clause 4.1.3):

• Employ masonry samples of uniform size to conduct comparative tests between different repellent classes.

Repellent Classes & Preparation:

• Classes A & B: Diluted with mineral spirit or xylene meeting the following:
  • Flash point ≥ 27°C
  • Boiling range 135–185°C
  • Kauri-Butanol value ≥ 34
  • Solids concentration ≥ 5% recommended
• Class C: Diluted with water free from wetting agents, soluble salts, and CO₂; maximum 3% solids to prevent sodium carbonate precipitation.

Important Considerations:

• Avoid exceeding 3% solids for Class C to prevent precipitate formation.
• Use equal-sized masonry specimens for absorption and repellency tests.
• Safety: Use airline respirators in confined spaces (Clause 6.3).

flowchart TD
    A[Select Uniform Masonry Samples] --> B{Are samples equal sized?}
    B -- Yes --> C[Test with Classes A, B, C]
    C --> D[Measure Water Absorption]
    D --> E[Choose Best Performing Repellent]

For full details, refer to IS 12054 clauses on specimen preparation and testing.

Guidelines for Preparing Surfaces for Silicone Water Repellents:

• Surface Condition:

  • Must be clean, dry, and devoid of dust, oils, grease, salts, loose debris, efflorescence, algae, or moss.
  • Remove contaminants by brushing or washing.

• Repairs:

  • Fill cracks and voids with suitable mortar compatible with the substrate before application.

• Moisture Level:

  • Surfaces should be dry or slightly damp, but not saturated, to ensure proper repellent penetration.

• Testing Samples:

  • Use masonry specimens of identical dimensions for repellent class selection via comparative treatment.

Preparation Steps:

1. Clean mechanically or with water wash.
2. Allow to dry naturally or by forced air.
3. Repair defects and cracks.
4. Remove dust after repairs before treatment.

Note: While IS 12054 emphasizes thorough cleaning and dryness, it does not prescribe specific formulas or tables for surface preparation.

flowchart TD
    A[Initial Surface] --> B{Is surface clean?}
    B -- No --> C[Clean (brush/wash)]
    C --> D{Is surface dry or slightly damp?}
    B -- Yes --> D
    D -- No --> E[Dry naturally or with air]
    D -- Yes --> F{Any cracks or damage?}
    F -- Yes --> G[Repair with suitable mortar]
    F -- No --> H[Ready for Repellent Application]

Summary: Thorough cleaning, dryness, and surface integrity are critical for effective silicone water repellent application.

Application Instructions for Silicone Water Repellents (Clauses 3.2.1, 3.2.2, 6.3):

• Operator Safety:

  • Avoid masks that trap solvent vapors.
  • Use airline respirators in enclosed spaces.

• Repellent Preparation:

• Units (SI):

Concentration Formula:

[ Solids ext{ concentration }= \frac{Weight ext{ of solids}}{Total ext{ weight of solution}} \times 100% ]

flowchart TD
    A[Select Repellent Class] --> B{Class A/B or C?}
    B -->|A/B| C[Prepare with Mineral Spirit/Xylene]
    B -->|C| D[Prepare with Water (≤3% solids)]
    C --> E[Maintain 3-5% solids; min 5% preferred]
    D --> F[Do not exceed 3% solids]
    E --> G[Apply with Safety Measures]
    F --> G
    G --> H[Use Airline Respirator in Confined Areas]

Reminder: Confirm solvent flash points and comply with safety protocols during application.