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

IS 10959 - 1984: Scope and Field of Application

• Scope: Defines technical terms related to sealants used in building construction.
• Application: Applies to joints filled with hardening, plastic, or elastic materials which are not preformed.
• Purpose: Standardizes terminology for sealants before elaborating specific test methods.
• Material Properties: Defined generally without quantitative test conditions (e.g., temperature, strain rate).

Key Definitions Relevant to Scope

Summary Diagram: Sealant Lifecycle in Application

flowchart LR
    A[Manufacture] --> B[Storage Period (Storage Life)]
    B --> C[Opening/ Mixing Sealant]
    C --> D[Application Period (Application Life)]
    D --> E[Joint Hardening/Performance]

This standard is a glossary, not a design or test method code. Use it as a reference for terminology in sealant specification and application.

IS 10959 (1984) - Key Terms & Definitions for Sealants

This standard aligns with ISO 6927-1981, defining terminology for sealants used in building joints filled with hardening, plastic, or elastic materials (non-preformed).

Important Terms:

• Storage Life (Clause 2.27)
  Period after manufacture during which a sealant, stored under specified conditions, retains its functional properties (i.e., performance remains satisfactory).

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

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

Notes:

• This glossary focuses on general material properties without quantitative test conditions (e.g., temperature effects).
• It supports uniform understanding before detailed test methods are introduced.

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

For detailed test methods and quantitative data, refer to subsequent IS or ISO standards.

IS 10959 – Key Points on "To Seal" and Sealants

• Definition (Clause 2.1):
  To seal means placing appropriate products in joints to prevent moisture or air penetration between elements, whether similar or dissimilar materials.

• Sealant (Clause 2.2):
  A material applied in an unformed state that adheres within the joint to create a seal.

• Sealant Durability (Clause 2.25):
  Expected service life of the sealant under specified conditions.

• Depth of Sealant (Clause 2.23):
  The minimum thickness of sealant from its surface to the back of the joint.

Important Specifications for Sealant Application:

Basic Sealant Joint Geometry:

graph LR
A[Joint Surface] -- Sealant --> B[Sealant Depth (d)]
B -- Backer Rod --> C[Joint Back]

• Use backer rods to control sealant depth and prevent three-sided adhesion.
• Proper sealant thickness ensures flexibility and durability.

Summary:
Sealants must be applied with correct depth and width to ensure durability and prevent moisture/air ingress, adhering to IS 10959 definitions and best practices.

IS 10959 - Sealant Key Points

• Definition (2.2): Sealant is an unformed material applied to joints that adheres to surfaces, preventing ingress of air, water, or dust.

• Types:

  • Plastic Sealant (2.4): Retains plasticity after application, relieving stresses quickly.
  • Multi-component Sealant (2.6): Supplied as separate components mixed before use.

• Durability (2.25): Sealant durability refers to its expected service life under specific conditions.

Common Specifications & Guidelines (from IS 10959 & general practice)

Basic Sealant Joint Design Formula:

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

Where:

• Movement = anticipated joint movement (mm)
• Movement Capability % = sealant's allowable movement percentage

Sealant Application Diagram

flowchart LR
    A[Joint Preparation] --> B[Primer Application (if needed)]
    B --> C[Sealant Mixing (multi-component)]
    C --> D[Sealant Application]
    D --> E[Tooling & Finishing]
    E --> F[Curing & Inspection]

Note: Always refer to manufacturer's datasheets and IS 10959 annexures for detailed tables on chemical resistance, adhesion, and curing times.

IS 10959: Elastic Sealant Key Points

• Elastic Sealant (Clause 2.3): Exhibits predominantly elastic behavior; stresses ∝ strain during joint movement.

• Elastic Recovery (Clause 2.16): Ability of sealant to return to original shape after deformation.

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

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

Typical Properties & Specifications (from IS 10959 & ISO 6927)

Application Tips

• Apply sealant in unformed state to fill joints fully (Clause 2.2).
• Ensure joint movement compatibility with sealant’s elastic strain capacity.
• Test sealant for elastic recovery to ensure durability under cyclic loads.

flowchart LR
    A[Joint Movement] --> B[Sealant Strain (ε)]
    B --> C[Stress in Sealant (σ)]
    C --> D[Elastic Behavior: σ ∝ ε]
    D --> E[Elastic Recovery after Load Removal]

Summary: Use sealants with high elastic recovery and appropriate secant tensile modulus to accommodate joint movements without cracking or loss of adhesion.

IS 10959 - Plastic Sealant: Key Points & Specifications

• Definition (Clause 2.4):
  Plastic sealant retains predominantly plastic behavior after application. It rapidly relieves stresses caused by joint movement, preventing stress buildup.

• Contrast with Elastic Sealant (Clause 2.3):
  Elastic sealants behave elastically, with stresses proportional to strain, unlike plastic sealants which deform plastically.

• Sealant Function (Clause 2.2):
  Sealants fill and adhere to joint surfaces, preventing ingress of water, air, or other substances.

• One Component Sealant (Clause 2.5):
  Ready-to-use sealants without mixing.

Typical Properties and Considerations for Plastic Sealants

Important Formula: Joint Width for Sealant

[ W = 2 \times M \times L ]

Where:

• (W) = Joint width (mm)
• (M) = Maximum expected movement (strain, decimal)
• (L) = Joint length (mm)

Summary Diagram: Behavior of Plastic vs Elastic Sealants

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

Note: For detailed mix design and application, refer to IS 10959 Annexures and manufacturer's datasheets.

IS 10959: One Component Sealant - Key Points

• Definition (Clause 2.5):
  One component sealant is a ready-to-use sealant, requiring no mixing before application.

• Application Life (Clause 2.19):
  For one component sealants, the application life is the time after opening the sealed container during which the sealant remains usable at a specified temperature.

• Specifications:

  • Should have good adhesion to joint surfaces without primer.
  • Must maintain elasticity and durability over time.
  • Should resist environmental factors like moisture, temperature changes, and UV radiation.

• Typical Properties to Check:

  Property	Typical Range/Value
  Shore A Hardness	20 - 50
  Tensile Strength	0.5 - 1.5 MPa
  Elongation at Break	200% - 600%
  Application Temperature	5°C to 40°C
  Skin Formation Time	10 - 30 minutes

• Usage Tips:

  • Use directly from the container.
  • Ensure joint surfaces are clean and dry.
  • Store sealed containers as per manufacturer’s instructions to maintain shelf life.

flowchart LR
    A[Sealant Container] -->|Open| B(One Component Sealant)
    B --> C[Apply to Joint]
    C --> D[Seal & Adhere]
    D --> E[Elastic & Durable Seal]

This ensures a simple, effective sealing process with minimal preparation.

IS 10959 – Multi-Component Sealant Key Points

• Definition (Clause 2.6): Multi-component sealants come in separate parts mixed before use per manufacturer's instructions, unlike one-component sealants ready for immediate use.

• Application Life (Clause 2.19): After mixing, the sealant must be applied within a specified time (application life), which depends on temperature.

Important Specifications:

• Mixing Ratio: Follow exact volumetric or weight ratios as per manufacturer.
• Pot Life (Application Life): Typically ranges from 15 min to 2 hours at 25°C, varies with temperature.
• Joint Dimensions: Sealant depth should be ~half the joint width, with typical joint width-to-depth ratio of 2:1.
• Adhesion: Sealant must adhere to joint faces but not the base (use bond-breaker tape).

Typical Formula for Joint Dimensions:

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

Table: Example Application Life vs Temperature

flowchart LR
    A[Separate Components] --> B[Mix as per instructions]
    B --> C[Apply within Application Life]
    C --> D[Seal Joint]

Summary: Mix multi-component sealants accurately, apply within pot life at given temperature, and maintain proper joint dimensions for effective sealing per IS 10959.

IS 10959 - Joint Movement Amplitude

Key Definitions (Clause 2.7):

• Extension/Compression Movement Amplitude (2.7.1):
  [ \text{Amplitude} = \text{Maximum joint width} - \text{Minimum joint width} ]

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

Movement Capability (Clause 2.8):

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

Typical Specification Table for Joint Movement Amplitude

Practical Formula for Sealant Movement Capability:

[ \text{Movement Capability} = \frac{\text{Total 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 Parallel to Joint]
    C --> F[Amplitude = Max Width - Min Width]
    E --> G[Amplitude = Max Sliding Length]

Summary:

• Measure extension/compression as width difference.
• Measure shearing as sliding displacement parallel to joint.
• Ensure sealant movement capability matches or exceeds joint movement amplitude for durability.

Movement Capability (IS 10959 - Clause 2.8) defines the sealant's ability to accommodate joint movements while maintaining the seal.

Key Definitions from IS 10959:

• Joint Movement Amplitude (2.7): The total range of movement in the joint.

  • Extension/Compression (2.7.1):
    [ \text{Amplitude} = W_{\max} - W_{\min} ] where ( W_{\max} ) and ( W_{\min} ) are the maximum and minimum joint widths.

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

Movement Capability Formula:

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

• Expressed as a percentage, it indicates how much the sealant can stretch or compress relative to its original width.

Typical Values (from IS 10959 and industry practice):

Summary Diagram:

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 length parallel to joint]
    F & G --> H[Calculate Movement Capability %]

Note: Always select sealants with movement capability exceeding expected joint movement amplitude for durability.

IS 10959 Primer Key Points

• Primer Definition (2.9): A surface coating applied on joint faces before sealant application to ensure adhesion.

• Open Time (2.21): The time window post-primer application during which the sealant must be applied for effective bonding.

• Back-up Material (2.10): Placed inside the joint to control sealant depth and shape the sealant profile.

• Sealant Type (2.5): One-component sealant is ready-to-use, applied after primer within open time.

Typical Primer Application Guidelines (General Practice)

Primer Function Flow

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 provide detailed formulas or tables for primers; follow manufacturer specs and ensure primer compatibility for optimal sealant performance.

IS 10959: Back-Up Material Key Points

• Definition (Clause 2.10):
  Back-up material is inserted in a joint to limit the depth of sealant and define the sealant’s back profile.

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

• Purpose of Back-Up Material:

  • Controls sealant thickness for optimum performance.
  • Prevents three-sided adhesion, allowing free movement.
  • Provides a firm base for tooling the sealant.

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

Typical Specifications for Back-Up Material:

Formula for 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: Use back-up material to control sealant depth, ensure proper elastic recovery, and prevent adhesion on the back side, ensuring durable, flexible joints per IS 10959.

IS 10959 - Compatibility of Sealants

Definition (Clause 2.11):
Compatibility means a sealant can remain in contact with another material without adverse physical or chemical reactions.

Key Points on Compatibility:

• No chemical degradation: Sealant must not react chemically with adjacent materials.
• No physical damage: No swelling, shrinking, or loss of adhesion due to interaction.
• Test compatibility: Often done by placing sealant in contact with substrate materials and observing changes over time.

Related Concepts:

Practical Compatibility Check (General Guidance):

• Perform adhesion tests on substrates.
• Check chemical resistance against adjacent materials.
• Evaluate movement accommodation to avoid sealant failure.

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

For detailed formulations and tests, refer to IS 10959 Annexures or manufacturer's datasheets.

IS 10959 - Cohesion in Sealants

• Definition (Clause 2.12):
  Cohesion is the internal strength of a sealant that allows it to resist tensile strain by intermolecular attraction.

• Cohesion Failure (Clause 2.13):
  Occurs when the sealant ruptures within its own body, not at the interface.

• Key Points:

  • Cohesion relates to the sealant's tensile strength and elasticity.
  • It is critical for sealant durability and integrity under stress.

Typical Formula for Tensile Strength (related to cohesion):

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

• (\sigma_t) = Tensile strength (cohesive strength)
• (F) = Applied tensile force
• (A) = Cross-sectional area of the sealant

Important Specifications:

Summary:

• Cohesion ensures the sealant holds together under tensile strain.
• Cohesion failure is rupture inside the sealant, distinct from adhesion failure.
• Sealants must balance cohesion and adhesion for effective sealing.

flowchart LR
    A[Tensile Strain Applied] --> B{Sealant Response}
    B -->|Cohesion Holds| C[Sealant Stretches]
    B -->|Cohesion Failure| D[Sealant Ruptures Inside]
    C --> E[Seal Maintained]
    D --> F[Seal Fails]

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

IS 10959: Cohesion Failure in Sealants

• Cohesion Failure (Clause 2.13): Rupture within the sealant body itself, indicating the internal strength limit is exceeded.
• Cohesion (Clause 2.12): Sealant's intrinsic tensile strength due to molecular attraction.
• Adhesion Failure (Clause 2.15): Rupture at sealant-substrate interface (contrast to cohesion failure).
• Secant Tensile Modulus (Clause 2.18):
  [ E_s = \frac{\sigma}{\varepsilon} ] Where:
  • (E_s) = secant tensile modulus
  • (\sigma) = tensile stress at a given elongation
  • (\varepsilon) = relative elongation (strain)

Key Points for Cohesion Failure:

• Occurs when tensile stress > sealant's cohesive strength.
• Avoided by selecting sealants with higher cohesive strength and proper curing.
• Testing involves tensile strain until rupture within sealant body.

Typical Test Data Table (Example):

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

Summary: Cohesion failure is an internal rupture of sealant under tensile strain, governed by its cohesive strength and secant tensile modulus. Proper sealant selection and testing per IS 10959 ensure durability.

IS 10959 Adhesion Key Points

• Adhesion (Clause 2.14): Sealant's ability to stick to a substrate surface.
• Adhesion Failure (Clause 2.15): Rupture at the sealant-substrate interface.
• Cohesion (Clause 2.12): Internal strength of sealant under tensile strain.
• Compatibility (Clause 2.11): Sealant's chemical/physical harmony with substrate.

Important Concepts:

Typical Adhesion Test (per IS 10959 & related standards):

• Test: Peel or tensile test to measure bond strength.
• Result: Adhesion strength (N/mm² or MPa).
• Failure Mode: Adhesion failure indicates poor bond; cohesion failure indicates weak sealant.

Formula for Adhesion Strength:

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

Summary:

• Ensure adhesion > cohesion for durable sealant performance.
• Check compatibility to avoid chemical breakdown.
• Use standard tests to quantify adhesion strength and failure mode.

flowchart LR
    Sealant -->|Adheres to| Substrate
    Sealant -->|Cohesive strength| Sealant
    AdhesionFailure -->|Interface rupture| Sealant & Substrate
    CohesionFailure -->|Internal rupture| Sealant