Glossary of terms for sealants for building purposes (ISO 6927-1981)
1984 Edition

IS 10959 - 1984: Scope and Application Domain

• Scope: Establishes terminology related to sealants utilized in building construction joints.
• Applicability: Pertains to joints filled with curing, plastic, or elastic substances not pre-shaped.
• Objective: Provides standardized definitions prior to specific test method descriptions.
• Material Attributes: Described qualitatively without fixed test parameters (e.g., temperature, strain rate).

Important Definitions within Scope

Diagram: Sealant Lifecycle during Use

flowchart LR
    A[Manufacturing] --> B[Storage Duration (Storage Life)]
    B --> C[Container Opening / Mixing]
    C --> D[Application Period (Application Life)]
    D --> E[Joint Curing and Performance]

Note: This document serves as a terminology reference, not a design or testing standard.

IS 10959 (1984) - Essential Terms and Definitions for Sealants

This standard corresponds with ISO 6927-1981, detailing terminology for sealants applied in joints filled with curing, plastic, or elastic materials (non-preformed).

Core Terms:

• Storage Life (Clause 2.27)
  Time span post-manufacture during which the sealant, kept under stipulated storage conditions, retains its intended properties.

• Secant Tensile Modulus (Clause 2.18)
  The ratio of tensile stress to relative elongation at a given strain:
  [ E_s = \frac{\sigma}{\varepsilon} ]
  where:

  • (E_s) = Secant tensile modulus
  • (\sigma) = Tensile stress at specified elongation
  • (\varepsilon) = Relative strain

Remarks:

• Definitions focus on general material properties without specifying quantitative test conditions such as temperature or strain rate.
• Supports uniform terminology comprehension before introducing detailed testing procedures.

flowchart LR
    A[Sealant] --> B[Storage Life]
    A --> C[Secant Tensile Modulus]
    B --> D[Functional Properties]
    C --> E[Tensile Stress / Strain Relationship]

For comprehensive test methods and quantitative data, consult related IS or ISO standards.

IS 10959 – Insights on "To Seal" and Sealants

• Meaning (Clause 2.1):
  To seal refers to applying suitable materials within joints to block moisture or air infiltration between components, regardless of whether materials are alike or different.

• Sealant (Clause 2.2):
  A substance applied in an unshaped form that adheres inside a joint to create a sealing barrier.

• Sealant Longevity (Clause 2.25):
  The expected operational lifespan of the sealant under specified conditions.

• Sealant Thickness (Clause 2.23):
  The minimal distance from the sealant surface to the rear of the joint.

Application Parameters:

Basic Joint Sealant Geometry:

graph LR
A[Joint Surface] -- Filled with Sealant --> B[Sealant Depth (d)]
B -- Backer Rod Positioned --> C[Rear of Joint]

• Use backer rods to regulate sealant depth and prevent adhesion on three surfaces.
• Appropriate sealant thickness is critical for maintaining flexibility and longevity.

Summary: Properly applied sealants with correct depth and width ensure effective moisture and air barrier in joints, aligned with IS 10959 terminology.

IS 10959 - Fundamental Sealant Concepts

• Definition (2.2): A sealant is an unshaped material applied to joints that bonds to surfaces, preventing ingress of air, water, or contaminants.

• Types:

  • Plastic Sealant (2.4): Maintains plasticity post-application, allowing rapid stress relief.
  • Multi-component Sealant (2.6): Provided as separate elements to be blended before use.

• Durability (2.25): Refers to the anticipated lifespan under particular conditions.

Typical Parameters & Recommendations (from IS 10959 and standard practice)

Basic Sealant Joint Dimension Calculation:

[ \text{Joint Width} = \frac{\text{Expected Movement} \times 100}{\text{Sealant Movement Capability (%)}} ]

Where:

• Expected Movement is the anticipated joint displacement (in mm)
• Movement Capability is the allowable percentage elongation/compression

Sealant Application Workflow

flowchart LR
    A[Joint Surface Preparation] --> B[Primer Application (if applicable)]
    B --> C[Mixing Sealant (for multi-component types)]
    C --> D[Sealant Application]
    D --> E[Tooling and Finishing]
    E --> F[Curing and Inspection]

Note: Always consult manufacturers' technical datasheets and IS 10959 annexes for detailed performance tables.

IS 10959: Overview of Elastic Sealants

• Elastic Sealant (Clause 2.3): Characterized by predominantly elastic response; stresses are proportional to strain during joint movement.

• Elastic Recovery (Clause 2.16): The sealant's ability to revert to its original shape after deformation.

• Secant Tensile Modulus (Clause 2.18):
  [ E_s = \frac{\sigma}{\varepsilon} ] where:

  • (E_s) = secant tensile modulus
  • (\sigma) = tensile stress at specific elongation
  • (\varepsilon) = relative strain

Typical Characteristics (According to IS 10959 & ISO 6927)

Application Recommendations

• Apply sealant in an unshaped form to fill joints fully (Clause 2.2).
• Ensure sealant's elastic strain capacity matches joint movement requirements.
• Verify elastic recovery through testing to guarantee durability under cyclic loading.

flowchart LR
    A[Joint Movement] --> B[Sealant Strain (ε)]
    B --> C[Stress Response (σ)]
    C --> D[Elastic Behavior: σ proportional to ε]
    D --> E[Recovery Post Load Removal]

Summary: Elastic sealants with high recovery and suitable modulus are essential for accommodating joint movements without cracking or detachment.

IS 10959 - Plastic Sealants: Key Attributes and Guidelines

• Definition (Clause 2.4): Plastic sealants primarily exhibit plastic deformation after application, allowing rapid stress dissipation from joint movements.

• Contrast with Elastic Sealants (Clause 2.3): Elastic sealants maintain stress proportional to strain, whereas plastic sealants deform plastically, relieving stress quickly.

• Sealant Role (Clause 2.2): Fill and adhere to joint surfaces to prevent ingress of moisture, air, or contaminants.

• One-Component Sealant (Clause 2.5): Pre-mixed, ready for immediate use.

Typical Properties and Considerations for Plastic Sealants

Joint Width Calculation Formula:

[ W = 2 \times M \times L ]

Where:

• (W) = joint width (mm)
• (M) = maximum expected strain (decimal)
• (L) = joint length (mm)

Diagram Comparing Behavior of Plastic and Elastic Sealants

graph LR
A[Joint Movement] --> B{Sealant Behavior Type}
B --> C[Elastic Sealant]
B --> D[Plastic Sealant]
C --> E[Stress Proportional to Strain]
D --> F[Stress Rapidly Relieved]

Note: For detailed formulation and application guidance, consult IS 10959 annexures and manufacturer instructions.

IS 10959: Single-Component Sealant Overview

• Definition (Clause 2.5): Sealants that are ready-to-use without requiring mixing before application.

• Application Life (Clause 2.19): The usable period after opening the container during which the sealant can be applied effectively at a specified temperature.

• Requirements:

  • Must adhere well to joint surfaces without primer.
  • Maintain elasticity and durability over the service period.
  • Resist environmental factors such as moisture, temperature fluctuations, and ultraviolet exposure.

• Typical Properties to Verify:

• Best Practices:
  • Apply directly from the container.
  • Ensure joint surfaces are clean, dry, and free of contaminants.
  • Store unopened containers as per manufacturer's recommendations to preserve shelf life.

flowchart LR
    A[Sealant Container] -->|Open| B(Single-Component Sealant)
    B --> C[Apply to Joint]
    C --> D[Seal and Bond]
    D --> E[Flexible and Durable Seal]

This allows for a straightforward sealing process with minimal preparation.

IS 10959 – Multi-Component Sealants Explained

• Definition (Clause 2.6): Sealants supplied as separate parts that must be combined according to manufacturer instructions before use, unlike one-component types.

• Application Life (Clause 2.19): The timeframe after mixing during which the sealant must be applied, dependent on temperature.

Key Specifications:

• Mixing Ratios: Precise volumetric or weight proportions as specified by the manufacturer.
• Pot Life (Application Life): Usually from 15 minutes to 2 hours at 25°C; varies with temperature.
• Joint Dimensions: Sealant depth about half the joint width; recommended width-to-depth ratio is 2:1.
• Adhesion: Sealant must bond to joint faces but avoid the base; use bond-breaker tape to prevent three-sided adhesion.

Joint Dimension Formula:

[ \text{Sealant Depth} = \frac{1}{2} \times \text{Joint Width} ]

Sample Application Life vs. Temperature Table

flowchart LR
    A[Separate Components] --> B[Mixing as per Instructions]
    B --> C[Apply Within Pot Life]
    C --> D[Seal the Joint]

Summary: Accurate mixing and timely application within pot life at given temperatures, combined with correct joint sizing, are crucial for effective sealing per IS 10959.

IS 10959 – Joint Movement Amplitude Explained

Definitions (Clause 2.7):

• Extension/Compression Movement Amplitude (2.7.1):
  [

  ext{Amplitude} = ext{Maximum joint width} - ext{Minimum joint width}

  ]

• Shearing Movement Amplitude (2.7.2):
  The maximal sliding displacement parallel to joint faces, initially perpendicular to the joint axis.

Movement Capacity (Clause 2.8):

• Defined as the greatest percentage of movement a sealant can endure relative to its original joint width without losing seal integrity.

Typical Movement Amplitude Ranges

Calculation for Movement Capability:

[ \text{Movement Capability} = \frac{\text{Total Joint Movement Amplitude}}{\text{Original Joint Width}} \times 100% ]

flowchart LR
    A[Joint Faces Initially Perpendicular] --> B[Extension/Compression Movement]
    B --> C[Change in Joint Width]
    A --> D[Shearing Movement]
    D --> E[Sliding Displacement Along Joint]
    C --> F[Amplitude = Max Width - Min Width]
    E --> G[Amplitude = Max Sliding Distance]

Summary: Measure extension/compression as the difference between maximum and minimum joint widths; measure shearing by maximum parallel displacement. Ensure sealant movement capability meets or exceeds joint movement amplitude for longevity.

Movement Capacity as per IS 10959 (Clause 2.8)

Definitions:

• Joint Movement Amplitude (2.7): The total range of joint displacement.

  • Extension/Compression (2.7.1):
    [

    ext{Amplitude} = W_{	ext{max}} - W_{	ext{min}}
    

    ] where (W_{ ext{max}}) and (W_{ ext{min}}) represent maximum and minimum joint widths respectively.

  • Shearing Movement (2.7.2):
    Maximum sliding distance parallel to the joint axis between two points initially aligned perpendicularly.

Movement Capacity Formula:

[ \text{Movement Capacity} = \frac{\text{Maximum Joint Movement}}{\text{Original Joint Width}} \times 100% ]

• Expressed as a percentage, it indicates the sealant's ability to stretch or compress relative to its original width without failure.

Typical Values (from IS 10959 and industry norms):

Visualization:

flowchart LR
    A[Original Joint Width] --> B[Joint Movement]
    B --> C{Type of Movement}
    C --> D[Extension/Compression]
    C --> E[Shearing]
    D --> F[Amplitude = Wmax - Wmin]
    E --> G[Amplitude = Max Sliding Distance]
    F & G --> H[Calculate Movement Capacity %]

Note: Select sealants with a movement capacity exceeding anticipated joint displacement to ensure durability.

Key Aspects of Primer as per IS 10959

• Primer Definition (2.9): A coating applied on joint surfaces before sealant placement to enhance adhesion.

• Open Time (2.21): The time frame after primer application during which sealant must be applied to achieve optimal bonding.

• Back-Up Material (2.10): Inserted in joints to regulate sealant thickness and shape.

• Sealant Type (2.5): Single-component sealants are applied after primer within the open time window.

Primer Application Guidelines

Primer Workflow

flowchart LR
    A[Clean Joint Surface] --> B[Apply Primer]
    B --> C{Within Open Time?}
    C -- Yes --> D[Apply Sealant]
    C -- No --> E[Reapply Primer]

Note: IS 10959 does not specify formulas or tables for primers; adhere to manufacturer instructions and ensure compatibility for best sealant adhesion.

IS 10959: Essentials of Back-Up Materials

• Definition (Clause 2.10): Material positioned inside a joint to limit sealant depth and define the sealant's back profile.

• Sealant Depth (Clause 2.23): The minimal distance between the sealant surface and the back-up material.

• Functions of Back-Up Material:

  • Controls sealant thickness for optimal mechanical performance.
  • Prevents adhesion to the joint base, avoiding three-sided adhesion.
  • Provides a stable base for tooling.

• Elastic Recovery (Clause 2.16): Sealants should have good recovery to maintain joint tightness after deformation.

Typical Back-Up Material Requirements:

Calculation of Sealant Depth:

[ \text{Sealant Depth} = \text{Joint Width} - \text{Back-Up Material Thickness} ]

flowchart LR
    A[Joint] --> B[Back-Up Material]
    B --> C[Sealant Layer]
    C --> D[Sealant Surface]
    B -->|Defines| E[Back Profile]
    E -->|Determines| F[Sealant Depth]

Summary: Applying back-up material ensures controlled sealant thickness, prevents undesired adhesion, and supports elastic recovery, all essential for durable, flexible joints as per IS 10959.

IS 10959 – Sealant Compatibility Overview

• Definition (Clause 2.11): The ability of a sealant to remain in contact with another material without harmful physical or chemical interactions.

Key Compatibility Considerations:

• No chemical degradation: Sealant should not chemically react with adjacent materials.
• No physical damage: No swelling, shrinkage, or loss of adhesion due to interaction.
• Testing: Compatibility is verified through contact tests observing changes over time.

Associated Terms:

Compatibility Evaluation Process:

• Conduct adhesion tests on substrates.
• Assess chemical resistance against adjacent materials.
• Evaluate movement accommodation to prevent failure.

flowchart LR
    A[Sealant] --> B[Contact with Substrate]
    B --> C{Compatible?}
    C -- Yes --> D[Seal Maintains Integrity]
    C -- No --> E[Sealant Failure: Swelling, Cracking, Loss of Adhesion]

For detailed compatibility tests and formulations, consult IS 10959 annexes or manufacturer documentation.

IS 10959 – Understanding Cohesion in Sealants

• Definition (Clause 2.12): Cohesion is the intrinsic internal strength of a sealant enabling it to resist tensile strain through molecular attraction.

• Cohesion Failure (Clause 2.13): Occurs when the sealant ruptures within its internal matrix rather than at the interface.

• Significance: Cohesion relates to tensile strength and elasticity critical for sealant durability.

Tensile Strength Formula Related to Cohesion:

[ \sigma_t = \frac{F}{A} ]

Where:

• (\sigma_t) = tensile (cohesive) strength
• (F) = applied tensile force
• (A) = sealant cross-sectional area

Typical Properties:

Summary:

• Cohesion ensures the sealant remains intact under tensile stress.
• Cohesion failure is internal rupture, distinct from adhesion failure at the interface.
• Effective sealing requires a balance between cohesion and adhesion.

flowchart LR
    A[Tensile Stress Applied] --> B{Sealant Response}
    B -->|Cohesion Maintained| C[Sealant Deforms]
    B -->|Cohesion Failure| D[Sealant Ruptures Internally]
    C --> E[Seal Maintained]
    D --> F[Seal Fails]

For detailed sealant selection and testing methods, refer to IS 10959.

IS 10959 – Cohesion Failure in Sealants

• Cohesion Failure (Clause 2.13): Rupture occurring within the sealant material itself, indicating the internal strength has been exceeded.
• Cohesion (Clause 2.12): The sealant's inherent tensile strength due to molecular bonds.
• Adhesion Failure (Clause 2.15): Rupture at the interface between sealant and substrate, contrasting cohesion failure.
• Secant Tensile Modulus (Clause 2.18):
  [ E_s = \frac{\sigma}{\varepsilon} ] Where:
  • (E_s) = secant tensile modulus
  • (\sigma) = tensile stress at certain elongation
  • (\varepsilon) = relative strain

Key Points:

• Cohesion failure transpires when tensile stress surpasses sealant's cohesive strength.
• Prevented by selecting sealants with sufficient cohesive strength and proper curing.
• Testing involves applying tensile strain until internal rupture.

Typical Test Data:

flowchart LR
    A[Applied Tensile Stress] --> B{Stress Level}
    B -->|Below Cohesive Strength| C[Sealant Stretches]
    B -->|Exceeds Cohesive Strength| D[Cohesion Failure: Internal Rupture]
    B -->|Exceeds Adhesion Strength| E[Adhesion Failure: Interface Rupture]

Summary: Cohesion failure is an internal breakage in the sealant caused by excessive tensile stress. Proper selection and curing per IS 10959 minimize such failures.

IS 10959 – Adhesion of Sealants

• Adhesion (Clause 2.14): The capability of a sealant to adhere to a substrate surface.
• Adhesion Failure (Clause 2.15): Rupture occurring at the sealant-substrate interface.
• Cohesion (Clause 2.12): Internal strength within the sealant under tensile stress.
• Compatibility (Clause 2.11): Chemical and physical compatibility between sealant and substrate.

Key Concepts:

Adhesion Testing (Per IS 10959 and Related Standards):

• Peel or tensile tests assess bond strength.
• Results expressed as adhesion strength (N/mm² or MPa).
• Adhesion failure indicates poor bonding; cohesion failure suggests weak sealant integrity.

Adhesion Strength Calculation:

[ \text{Adhesion Strength} = \frac{\text{Force at Failure (N)}}{\text{Bonded Area (mm}^2)} ]

Summary:

• Adhesion strength must exceed cohesion for reliable sealing.
• Compatibility with substrates prevents breakdown.
• Standardized tests quantify adhesion and identify failure modes.

flowchart LR
    Sealant -->|Adheres to| Substrate
    Sealant -->|Internal Strength| Sealant
    AdhesionFailure -->|Interface Rupture| Sealant & Substrate
    CohesionFailure -->|Internal Rupture| Sealant