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

IS 12118 Part 2 (1987) - Foreword Summary & Key Points

• Scope: Methods of tests for two-part polysulphide-based sealants used in building construction.
• Sealant Composition: Two components—polysulphide polymer + curing agent mixed before application; cures at ambient temperature to a rubber-like solid.
• Usage: Suitable for normal atmospheric environments in general building applications.
• Special Conditions: For extreme temperature/humidity variations, reduced joint resilience (< ¼ joint width), basement walls under water pressure, or potable water storage, special performance tests are necessary.
• Standard Basis: Adapted from BS 4254:1983.
• Standard Parts:
  • Part 1: General requirements
  • Part 2: Methods of tests (this document)

Key Test Reporting Requirements (Clause 8.4)

Typical Sealant Properties to Test (from IS 12118 Part 2 context & general knowledge):

Conceptual Diagram: Two-Part Sealant Application

flowchart LR
    A[Component 1: Polysulphide Polymer] --> C[Mixing]
    B[Component 2: Curing Agent] --> C
    C --> D[Application to Joint]
    D --> E[Curing at Ambient Temperature]
    E --> F[Rubber-like Solid Sealant]

Note: For detailed test procedures, refer to clauses 4.6 and 7.2 of IS 12118 Part 2.

IS 12118 (Part 2) - 1987: Scope Summary & Key Specifications

• Scope: Methods of tests for two-part polysulphide-based sealants used in building construction.
• Sealant Composition: Two components (polysulphide polymer + curing agent), mixed before application, curing at ambient temperature to rubber-like solid.
• Application: General building environments; special conditions (high temp/humidity variations, water pressure, potable water) require additional testing.

Key Test Assemblies (Clause 4.6.3 & Fig.1):

• Test surfaces: Aluminium (3 mm) or Glass (6 mm)
• Spacer dimensions: 12×13×50 mm or variations (e.g., 12×38×50 mm)
• Sealant sample size: 12×12×50 mm
• Typical assemblies:
  • 1A: Prepared surfaces before sealant placement
  • 1B: Mortar test assembly
  • 1C: Aluminium and glass test surfaces
  • 1D & 1E: Variations with spacer bars

Water Immersion Test (Clause 4.6.3):

• Immerse test assemblies in distilled water at 27 ± 2°C for 7 days.
• Condition for ≥4 hours at 27 ± 2°C before further testing.

Test Report Requirements (Clause 8.4):

• Record staining occurrence (primed/unprimed surfaces).
• Record batch number and primer expiry (if applicable).

Typical Test Assembly Dimensions (mm)

Summary Diagram of Test Assembly (Type 1)

graph LR
A[Aluminium/Glass Plate (3/6 mm)] -- Sealant (12x12x50) --> B[Spacer Bar (12x13x50)]
B --> C[Aluminium/Glass Plate (3/6 mm)]
direction LR

This standard ensures reliable testing for adhesion, tensile modulus, and durability

IS 12118 Part 2: Conditioning and Mixing of Sealants

Key Specifications:

• Conditioning:

  • Base and curing components in closed containers for ≥16 hours.
  • Temperature: 27 ± 2°C (or 5 ± 2°C as per clause 2.2.1).
  • Relative Humidity: 65 ± 5% (where applicable).
  • Metal channels conditioned similarly for ≥1 hour.

• Mixing:

  • Use a clean cylindrical container.
  • Mix by hand with a spatula for 10 minutes or use a powered stirrer.
  • Stir at a speed minimizing air entrainment.
  • Ensure uniform dispersion of curing component in base.
  • Store mixed sealant at conditioning temperature for 30 minutes (if specified).

Procedure Summary

Testing Immediately After Mixing (Clause 2.3.2.1)

• Fill conditioned channels immediately.
• Strike off surplus with minimal strokes.
• Test at 5 ± 2°C and 35 ± 2°C for 24 hours.

a) Vertical channel test:

• Draw transverse mark across sealant.
• Suspend vertically.
• Measure slump as vertical distance between V-notches and lowest point of slump.

b) Horizontal channel test:

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

Important Notes

• Keep air entrainment minimal to avoid voids.
• Uniform mixing ensures consistent curing and performance.
• Conditioning stabilizes material properties before mixing.

flowchart TD
    A[Condition base & curing components] -->|≥16h at 27±2°C

Plastic Deformation Calculation (IS 12118 Part 2)

Formula (Clause 3.3):

[ D (%) = \frac{W_{ar} - W_i}{W_e - W_i} \times 100 ]

• D = Plastic deformation (%)
• W_i = Initial width (mm)
• W_e = Width extended (mm)
• W_ar = Width after recovery (mm)

Notes:

• Measure widths accurately in mm.
• Plastic deformation indicates permanent set after unloading.
• Record D in the test report (Clause 3.4).

Additional Test Specifications:

• Adhesion & Tensile Modulus (Clause 4):

  • Vertical channels: Measure slump (mm) and check for detachment/slippage.
  • Horizontal channels: Measure protrusion (mm) beyond original profile.

• Test Setup (Clause 8.1.2):

  • Use a cylindrical mandrel made of polyethylene or similar material for deformation tests.

Summary Table:

flowchart LR
    Wi[Initial Width (Wi)]
    We[Extended Width (We)]
    War[Width After Recovery (War)]
    D[Plastic Deformation (D %)]

    Wi --> D
    We --> D
    War --> D

This formula quantifies permanent deformation after stretching and recovery, critical for sealant performance evaluation.

IS 12118 Part 2: Test for Adhesion and Tensile Modulus

Key Specifications:

• Test Assemblies: Aluminium (3 mm) or Glass (6 mm) plates with sealant (12×12×50 mm) and spacers (various sizes).
• Curing: 7 days at room temp, then oven at 50 ± 2°C for 3 days.
• Conditioning: 16 h at 27 ± 2°C before testing.
• Extension Rate: 5 to 6 mm/min until 30 mm total width.
• Hold Extension: 5 min during test, then recover 1 h at 27 ± 2°C.

Test Procedure Summary:

1. Pull assembly to 30 mm width at 5-6 mm/min.
2. Hold extension for 5 min.
3. Remove and allow 1 h recovery without compression.
4. Measure force at extension → Tensile Force (F).
5. Calculate Adhesion Failure Area (length × depth of cracks).
6. After water immersion (7 days at 27 ± 2°C), repeat test.

Key Formulas:

• Tensile Modulus, E:

[ E = \frac{\sigma}{\epsilon} = \frac{F/A}{\Delta L / L_0} ]

Where:

• ( F ) = Force at extension (N)

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

• ( \Delta L ) = Extension (30 mm)

• ( L_0 ) = Original length (50 mm)

• Plastic Deformation (%) (Clause 3.4):

[ \text{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 (mm):

IS 12118 Part 2: Conditioning and Mixing Procedures

Key Specifications:

• Conditioning of components:

  • Base and curing components in closed containers.
  • Duration: At least 16 hours.
  • Temperature & Humidity:
    • Typically 27 ± 2°C, 65 ± 5% RH (Clause 2.3.1).
    • Alternative: 5 ± 2°C (Clause 2.2.1).
  • Metal channels conditioned at 27 ± 2°C for ≥1 hour.

• Mixing:

  • Use a clean cylindrical container.
  • Mix by hand (spatula) or power stirrer for 10 minutes.
  • Goal: Achieve uniform mixing with minimum air entrainment.
  • Mixed sealant should be stored for 30 minutes before use (Clause 2.2.1).

• Application life testing:

  • Store mixed sample uncovered in humidity cabinet.
  • Test every 10 minutes starting 30 minutes before expiry.
  • Ensure easy application by spatula on clean aluminium surface (Clause 5.5).

Summary Table:

flowchart TD
    A[Condition base & curing components] --> B[Condition metal channels]
    B --> C[Mix components for 10 min]
    C --> D[Store mixed sealant for 30 min]
    D --> E[Application life testing every 10 min]

This ensures consistent sealant quality and workability per IS 12118 Part 2.

IS 12118 Part 2 — Test for Adhesion in Peel: Key Points

Test Setup (Clause 6.4.5)

• Cut sealant + backing into 25 mm wide strips, spaced 10 mm apart (Fig. 3).
• Immerse assembly in distilled/deionized water at 27 ± 2°C for 7 days.

Test Procedure (Clause 6.5.2)

• Pull one backing strip at a separation rate of 50 mm/min for 1 min.
• Record peel strength (N) after steady state is reached.
• Measure the area of adhesion failure on the test surface.
• If backing peels from sealant, discard and repeat.

Reporting (Clause 6.6)

• Report the average peel strength (N) per test surface.
• Report the area of sealant adhesion failure for each strip.

Formula for Peel Strength (N/mm width)

[ \text{Peel Strength} = \frac{\text{Force (N)}}{\text{Width of strip (mm)}} ]

• Width = 25 mm (standard strip width)

Diagram (Fig. 3 arrangement)

graph LR
A[Sealant + Backing Material] --> B[Cut into 25 mm strips]
B --> C[10 mm gap between strips]
C --> D[Immersion in water at 27±2°C for 7 days]

This test ensures sealant adhesion durability on aluminum surfaces under wet conditions.

IS 12118 Part 2: Test for Loss of Mass after Heat Ageing

Procedure Summary (Clauses 7.2.3 & 4.6.4)

• Cure 3 specimens for 7 days at 27 ± 2°C and 65 ± 5% RH.
• Age specimens in a ventilated oven for 14 days at 70 ± 2°C.
• Cool specimens for 2 hours at standard lab conditions (27 ± 2°C).
• Measure final mass ( m_3 ) (in grams).

Key Formula for Mass Loss

[ \text{Loss of Mass (%)} = \frac{m_1 - m_3}{m_1} \times 100 ]

• ( m_1 ) = Original mass before heat ageing (g)
• ( m_3 ) = Mass after heat ageing (g)

Reporting (Clause 7.4)

• Record loss of mass % for each specimen.
• Calculate and report average loss of mass % for all three specimens.

Important Specifications

flowchart TD
    A[Cure specimens at 27°C, 7 days] --> B[Heat age at 70°C, 14 days]
    B --> C[Cool specimens at 27°C, 2 hours]
    C --> D[Measure mass after heat ageing (m3)]
    D --> E[Calculate % loss of mass]
    E --> F[Report individual and average loss]

This ensures sealant durability assessment under thermal ageing conditions per IS 12118 Part 2.

Preparation of Mortar Blocks (IS 12118 Part 2 - Clauses 4.2.3, 6.2.3, 8.2)

Key Specifications:

• Mortar Mix Ratio:
  • Cement : Sand = 1 : 3 (by dry mass)
  • Water/Cement ratio = 0.35 to 0.40
• Sand Requirements:
  • 100% passing 850 µm sieve
  • ≤10% passing 600 µm sieve
  • Sand must be washed and dried
• Block Size:
  • Approximately 125 × 75 × 25 mm
  • Minimum thickness: 12 mm
• Curing:
  • 24 h in mould at ≥90% RH
  • Then 28 days submerged in water at room temperature
  • Followed by drying at 110°C for 12 h
  • Store at 27 ± 2°C and 65 ± 5% RH for at least 28 days

Preparation Steps:

1. Dry mix cement and sand uniformly.
2. Add water to form a smooth paste.
3. Cast mortar in rigid plastic moulds in 4 layers, compacting each layer on a vibrating table.
4. Cure as per above.

Additional Notes (Clause 8.2.2):

• For lime cement mortar, mix dry cement, lime, and sand, add water, and cast in split ring mould with a 20 mm diameter central hole (using a mandrel).

Summary Table:

IS 12118 Part 2: Key Test Report Requirements

3.4 Plastic Deformation Test Report

• Record plastic deformation (%) calculated as per Clause 3.3.

4.7 Adhesion and Tensile Modulus Test Report

For each test assembly, record:

• Force (N) required to produce extension.
• Total failure area (length × depth in mm²) of adhesion/cohesion failure.
• Crack depth (mm).

7.4 Application Life Test Report

Record:

• Loss of mass (%) for each specimen.
• Average loss of mass (%) for three specimens.

Summary Table of Key Recorded Parameters

This structured data ensures consistent and comprehensive test reporting as per IS 12118 Part 2.