Two parts polysulphide based sealants - Specification, Part 2: Methods of test
1987 Edition

Overview of Testing Protocols for Two-Part Polysulphide Sealants

• Purpose: Defines test methods for two-component polysulphide-based sealants in construction.
• Composition: Sealants comprise a polysulphide polymer and a curing agent, mixed prior to application; cure at room temperature to form an elastic solid.
• Application Environment: Intended for standard atmospheric conditions in building projects.
• Special Considerations: Additional testing required for extreme temperature/humidity ranges, reduced joint flexibility, submerged basement walls, or potable water containment.
• Origin: Adapted from British Standard BS 4254:1983.
• Related Sections:
  • Part 1: General requirements
  • Part 2: Testing methods (this document)

Reporting Essentials (Clause 8.4)

Typical Properties Evaluated:

Process Flow: Two-Part Sealant Application

flowchart LR
    A[Polysulphide Polymer Component] --> C[Mixing Process]
    B[Curing Agent Component] --> C
    C --> D[Sealant Application into Joint]
    D --> E[Curing at Ambient Temperature]
    E --> F[Final Elastic Solid Sealant]

Refer to Clauses 4.6 and 7.2 for detailed test procedures.

Scope of Testing and Assembly Specifications

• Scope: Procedures for evaluating two-part polysulphide sealants used in building construction.
• Composition: Two components (polysulphide polymer and curing agent), combined before use, curing into an elastic solid at ambient temperature.
• Application Range: Suitable for general building atmospheres; special tests needed for extreme climates or water pressure scenarios.

Specimen Assemblies (Clause 4.6.3 & Figure 1):

• Test substrates: Aluminium plates (3 mm thick) or glass sheets (6 mm thick)
• Spacer bar dimensions: 12×13×50 mm or alternates like 12×38×50 mm
• Sealant sample size: 12×12×50 mm
• Assembly Types:
  • 1A: Prepared substrates prior to sealant placement
  • 1B: Mortar-based test assembly
  • 1C: Aluminium and glass substrate assembly
  • 1D & 1E: Variations with different spacer bars

Water Immersion Conditioning:

• Immerse test samples in distilled water at 27 ± 2°C for 7 days.
• Post-immersion conditioning for at least 4 hours at 27 ± 2°C before further testing.

Test Reporting (Clause 8.4):

• Note any staining on substrates (primed or unprimed).
• Include batch number and primer expiry date if primers were used.

Assembly Dimensions (millimeters)

Assembly Diagram (Type 1)

graph LR
A[Aluminium/Glass Plate (3/6 mm)] -- Sealant (12×12×50) --> B[Spacer Bar (12×13×50)]
B --> C[Aluminium/Glass Plate (3/6 mm)]
direction LR

This section ensures reproducibility for adhesion, tensile modulus, and endurance testing.

Procedures for Conditioning and Blending Sealant Components

Main Requirements:

• Conditioning:

  • Both base and curing components must be kept in sealed containers for a minimum of 16 hours.
  • Maintain temperature at either 27 ± 2°C (recommended) or 5 ± 2°C (alternative per clause 2.2.1).
  • Relative humidity maintained at 65 ± 5% where applicable.
  • Metal channels used for testing should be conditioned under similar conditions for at least one hour.

• Mixing:

  • Use a clean cylindrical container to combine components.
  • Mix manually with a spatula for 10 minutes or employ a mechanical stirrer operating at a speed that minimizes air bubble inclusion.
  • Ensure curing agent is thoroughly dispersed within the base polymer.
  • After mixing, the sealant should be stored at conditioning temperature for 30 minutes if specified.

Summary Table

Immediate Post-Mixing Testing (Clause 2.3.2.1)

• Fill conditioned metal channels promptly after mixing.
• Remove excess sealant with minimal strokes.
• Conduct tests at 5 ± 2°C and 35 ± 2°C after 24 hours.

Vertical Channel Test:

• Mark transverse lines on sealant.
• Suspend vertically and measure slump as vertical distance between notches and lowest slump point.

Horizontal Channel Test:

• Position channel horizontally with open side vertical.
• Measure sealant protrusion beyond original profile.

Important Considerations

• Avoid entrainment of air to prevent voids.
• Uniform mixing is critical for consistent curing and performance.
• Conditioning stabilizes raw material properties prior to mixing.

flowchart TD
    A[Condition base and curing components] -->|≥16h at 27±2°C| B[Condition metal channels (≥1h)]
    B --> C[Mix components in clean container]
    C --> D[Mix by hand or machine (10 min)]
    D --> E[Store mixed sealant for 30 min]

Calculation Method for Plastic Deformation

Formula (Clause 3.3):

[ D(%) = \frac{W_{recovered} - W_{initial}}{W_{extended} - W_{initial}} \times 100 ]

Where:

• (D): Plastic deformation percentage
• (W_{initial}): Initial width of sealant specimen (mm)
• (W_{extended}): Width after extension (mm)
• (W_{recovered}): Width after recovery post extension (mm)

Notes:

• Accurate width measurements in millimeters are essential.
• Plastic deformation quantifies permanent set after unloading.
• Report the calculated deformation value in test results (Clause 3.4).

Additional Test Details:

• Adhesion and tensile modulus tests involve measuring slump in vertical channels and protrusion in horizontal channels (Clause 4).
• Test assemblies utilize cylindrical polyethylene mandrels for deformation evaluation (Clause 8.1.2).

Parameter Summary

flowchart LR
    Wi[Initial Width W_i] --> D
    We[Extended Width W_e] --> D
    Wr[Recovered Width W_{ar}] --> D
    D[Plastic Deformation %]

This calculation is crucial to evaluate permanent deformation affecting sealant performance.

Procedures for Assessing Adhesion and Tensile Modulus of Sealants

Test Setup:

• Use aluminium (3 mm thick) or glass (6 mm thick) plates with sealant samples measuring 12×12×50 mm.
• Spacer bars of varying dimensions used to assemble test specimens.
• Cure specimens for 7 days at ambient temperature followed by 3 days at 50 ± 2°C in an oven.
• Condition test specimens for 16 hours at 27 ± 2°C prior to testing.
• Extension rate during tensile testing is maintained between 5 to 6 mm per minute until a total extension of 30 mm.
• Hold the extension for 5 minutes, then allow specimens to recover for 1 hour at 27 ± 2°C without compression.

Test Procedure:

1. Extend the test assembly to 30 mm at specified rate.
2. Maintain extension for 5 minutes.
3. Remove load and permit 1 hour recovery.
4. Record tensile force at extension (F).
5. Calculate adhesion failure area (length × depth of cracks).
6. Repeat tests after water immersion conditioning (7 days at 27 ± 2°C).

Key Calculations:

• Tensile Modulus (E): [ E = \frac{\sigma}{\epsilon} = \frac{F/A}{\Delta L / L_0} ] Where:

• (F): Tensile force at extension (Newtons)

• (A): Cross-sectional area of sealant (mm²)

• (\Delta L): Extension (30 mm)

• (L_0): Original specimen length (50 mm)

• Plastic Deformation (%): [ \frac{L_f - L_0}{L_0} \times 100 ] Where:

• (L_f): Final length after recovery

• (L_0): Original length

Typical Assembly Dimensions:

This testing verifies adhesive strength and elastic properties under simulated service conditions.

Guidelines for Conditioning and Combining Sealant Components

Conditioning:

• Store base and curing agents in sealed containers for no less than 16 hours.
• Maintain temperature at 27 ± 2°C with relative humidity of 65 ± 5% (Clause 2.3.1).
• Alternatively, conditioning can be conducted at 5 ± 2°C (Clause 2.2.1).
• Metal channels used for testing must be conditioned at 27 ± 2°C for at least one hour.

Mixing:

• Utilize a clean cylindrical container for blending components.
• Mix manually with a spatula or mechanically for 10 minutes.
• Ensure thorough, uniform mixing with minimal air entrainment.
• After mixing, allow the sealant to rest in the conditioning environment for 30 minutes before use.

Application Life Testing:

• Store mixed sealant uncovered in a humidity chamber.
• Conduct application ease tests every 10 minutes starting 30 minutes before the material’s expiration time.
• Confirm spatula application remains smooth on clean aluminium surfaces.

Summary Table:

flowchart TD
    A[Condition base & curing agents] --> B[Condition metal channels]
    B --> C[Mix components for 10 minutes]
    C --> D[Store mixed sealant for 30 minutes]
    D --> E[Conduct application life tests every 10 minutes]

These steps assure consistent quality and usability as per IS 12118 Part 2.

Test Procedure for Peel Adhesion of Sealants

Sample Preparation (Clause 6.4.5):

• Cut sealant and backing material into strips 25 mm wide with 10 mm spacing between strips (see Fig. 3).
• Immerse the assembled specimen in distilled or deionized water maintained at 27 ± 2°C for 7 days.

Testing Method (Clause 6.5.2):

• Peel one strip of backing material at a constant rate of 50 mm per minute for 1 minute.
• Record the peel strength in Newtons once a steady reading is achieved.
• Measure the area of sealant adhesion failure on the substrate.
• If the backing separates from the sealant, discard the result and repeat the test.

Reporting (Clause 6.6):

• Report the mean peel strength per test surface.
• Document the adhesion failure area for each strip.

Peel Strength Calculation (N/mm strip width):

[ \text{Peel Strength} = \frac{\text{Force (N)}}{25 \text{ mm}} ]

Test Setup Diagram (Fig. 3)

graph LR
A[Sealant with Backing] --> B[Cut into 25 mm wide strips]
B --> C[10 mm gap between strips]
C --> D[7-day immersion in water at 27 ± 2°C]

This test evaluates the durability of sealant adhesion on substrates under wet conditions.

Procedure for Assessing Mass Loss Post Heat Aging

Steps (Clauses 7.2.3 & 4.6.4):

• Cure three test specimens for 7 days at 27 ± 2°C and 65 ± 5% relative humidity.
• Subject specimens to heat aging in a ventilated oven at 70 ± 2°C for 14 days.
• Allow specimens to cool for 2 hours under laboratory conditions (27 ± 2°C).
• Weigh specimens to obtain final mass (m_3) in grams.

Mass Loss Calculation:

[ \text{Percentage Mass Loss} = \frac{m_1 - m_3}{m_1} \times 100 ] Where:

• (m_1): Initial mass before heat aging (g)
• (m_3): Mass after heat aging (g)

Reporting (Clause 7.4):

• Document mass loss percentage for each specimen.
• Calculate and report the average mass loss across the three specimens.

Test Parameters:

flowchart TD
    A[Cure specimens at 27°C for 7 days] --> B[Heat age at 70°C for 14 days]
    B --> C[Cool specimens at 27°C for 2 hours]
    C --> D[Measure post-aging mass]
    D --> E[Calculate mass loss percentage]
    E --> F[Report individual and average results]

This test measures sealant stability under thermal aging conditions.

Guidelines for Fabrication of Mortar Blocks for Testing

Mix Specifications:

• Cement to sand ratio: 1:3 by dry weight.
• Water to cement ratio: Between 0.35 and 0.40.
• Sand grading:
  • 100% passing 850 µm sieve.
  • Not more than 10% passing 600 µm sieve.
• Sand must be thoroughly washed and dried.

Block Dimensions:

• Approximately 125 mm length × 75 mm width × 25 mm thickness.
• Minimum block thickness: 12 mm.

Curing Process:

• Initial curing for 24 hours inside mold at relative humidity ≥ 90%.
• Subsequent water curing submerged for 28 days at room temperature.
• Dry blocks at 110°C for 12 hours.
• Store at 27 ± 2°C and 65 ± 5% relative humidity for at least 28 days before testing.

Preparation Steps:

1. Uniformly dry mix cement and sand.
2. Add water to produce a smooth mortar paste.
3. Cast mortar into rigid plastic molds in four layers, compacting each layer using vibration.
4. Follow the curing regime as detailed.

Additional Information (Clause 8.2.2):

• For lime cement mortar, mix dry cement, lime, and sand, add water, and mold using a split ring with a 20 mm diameter core.

Summary Table:

Key Requirements for Test Documentation

Plastic Deformation Reporting (Clause 3.4):

• Document the percentage plastic deformation calculated according to Clause 3.3.

Adhesion and Tensile Modulus Reporting (Clause 4.7):

• For each test specimen, record:
  • Force applied (in Newtons) to achieve extension.
  • Total area of adhesion/cohesion failure (length × depth in mm²).
  • Crack depth (in millimeters).

Application Life Test Reporting (Clause 7.4):

• Record percentage mass loss for each specimen.
• Calculate and report average mass loss for all specimens.

Summary Table of Recorded Parameters

This framework ensures comprehensive and uniform test result reporting in accordance with IS 12118 Part 2.