Glossary of terms relating to cement concrete, Part II: Materials (Other than Cement and Aggregate)

IS 6461 Part 2: Scope Summary

• Scope: Defines terms related to materials other than cement and aggregates used in concrete.
• Purpose: Standardizes terminology for materials like admixtures, additives, and other concrete constituents.
• Applicability: Useful for engineers, material suppliers, and quality control in concrete construction.
• Relation to other parts:
  • Part I: Concrete aggregates
  • Part III: Concrete reinforcement
  • Part IV: Types of concrete
  • Part VIII: Properties of concrete
  • Part IX: Structural aspects

Key points:

No direct formulas or tables are specified in the Scope clause since it primarily defines terminology.

Visual: IS 6461 Series Structure

graph TD
  A[IS 6461 Series] --> B[Part I: Aggregates]
  A --> C[Part II: Materials (excluding cement & aggregates)]
  A --> D[Part III: Reinforcement]
  A --> E[Part IV: Types of Concrete]
  A --> F[Part V: Formwork]
  A --> G[Part VI: Equipment]
  A --> H[Part VII: Construction Processes]
  A --> I[Part VIII: Properties]
  A --> J[Part IX: Structural Aspects]
  A --> K[Part XI: Prestressed Concrete]
  A --> L[Part XII: Miscellaneous]

For detailed definitions, refer directly to IS 6461 Part 2 text.

IS 6461 Part 2: Terms and Definitions (Materials other than Cement and Aggregates)

This part of IS 6461 provides standardized definitions for materials used in concrete other than cement and aggregates, ensuring clarity and uniformity in communication.

Key Points:

• Scope: Definitions cover admixtures, water, supplementary cementitious materials, and other concrete additives.
• Purpose: To standardize terminology for materials affecting concrete properties.

Typical Definitions Include:

Notes:

• No direct formulas in this clause; it focuses on terminology.
• For design and mix calculations, refer to IS 456 and IS 10262.

flowchart LR
    A[Concrete Materials] --> B[Cement]
    A --> C[Aggregates]
    A --> D[Admixtures & SCMs]
    D --> E[Fly Ash]
    D --> F[Slag]
    D --> G[Water]

Summary: IS 6461 Part 2 standardizes terms related to non-cement, non-aggregate materials in concrete, facilitating clear communication and proper material usage.

IS 6461 Part 2: Accelerator - Key Points

• Definition (Clause 2.1):
  An accelerator is a substance added to concrete, mortar, or grout to:
  • Increase the rate of hydration of hydraulic cement
  • Shorten setting time
  • Increase rate of hardening or strength development

Typical Specifications for Accelerators (General Practice)

Important Notes:

• Calcium Chloride is the most common accelerator but limited to max 2% due to corrosion risk.
• Accelerators must comply with IS 9103 (Admixtures for concrete).
• Use accelerators cautiously in reinforced concrete to avoid steel corrosion.
• Accelerators are essential in cold weather concreting to prevent delayed setting.

flowchart LR
    A[Add Accelerator] --> B[Increased Hydration Rate]
    B --> C[Shorter Setting Time]
    B --> D[Early Strength Gain]
    D --> E[Improved Construction Speed]

For detailed chemical compositions and test methods, refer to IS 9103 and IS 6461 Part 2 annexures.

IS 6461 Part 2 (1972) - Key Points on Addition

• Addition (Clause 2.2):
  Material blended/interground in limited amounts into hydraulic cement during manufacture.

  • Purpose:
    • Processing addition: aids manufacturing/handling.
    • Functional addition: modifies finished cement properties.

• Additive (Clause 2.3):
  Refers to the material defined under Addition (2.2).

• Admixture (Clause 2.4):
  Different from addition; added to concrete/mortar batch before or during mixing to modify fresh/hardened properties.

Typical Specifications for Additions in Hydraulic Cement

Notes:

• IS 6461 Part 2 focuses on terminology; detailed quantitative formulas or tables for additions are typically found in related IS codes like IS 1489 (Fly ash) or IS 3812 (Pozzolanic materials).
• Additions affect hydration kinetics and durability; selection depends on desired cement properties.

flowchart LR
    A[Hydraulic Cement] --> B[Addition]
    B --> C{Type}
    C --> D[Processing Addition]
    C --> E[Functional Addition]
    A --> F[Admixture (added during mixing)]

For detailed mix design or performance formulas, refer to IS 456 and IS 1489.

IS 6461 Part 2: Admixtures - Key Points

Definitions:

• Admixture (2.4): Any material other than water, aggregates, or cement added to concrete/mortar to modify properties.
• Air-Entraining Agent (2.6): Adds microscopic air bubbles to improve workability & frost resistance.
• Retarder (2.30): Delays cement setting time.
• Dispersing Agent (2.20): Improves fluidity by reducing particle attraction.

Typical Specifications & Usage:

Important Formulas:

• Water Reduction (%) by dispersing agents:
  [ \text{Water Reduction} = \frac{W_0 - W_a}{W_0} \times 100 ]
  Where (W_0) = water content without admixture, (W_a) = water content with admixture.

• Air Content (%) by air-entraining agents:
  Measured by pressure method or volumetric method per IS 1199.

Notes:

• Dosages are trial-based; always verify with manufacturer.
• Compatibility with cement and other admixtures must be checked.
• IS 9103 provides guidelines on admixture use in concrete.

flowchart LR
    A[Admixture] --> B[Air-Entraining Agent]
    A --> C[Retarder]
    A --> D[Dispersing Agent]
    B --> E[Improves frost resistance]
    C --> F[Delays setting time]
    D --> G[Increases fluidity]

IS 6461 Part 2: Air-Entraining Key Points

• Air-Entraining (Clause 2.5): Incorporation of microscopic air bubbles in cement paste/mortar/concrete to improve durability and workability.

• Air-Entraining Agent (Clause 2.6): Additive causing uniform air bubbles, enhancing frost resistance and workability.

• Air-Entraining Hydraulic Cement (Clause 2.7): Cement pre-mixed with air-entraining agent to maintain air content within specified limits.

Important Specifications:

Key Formula: Air Content Estimation

[ \text{Air Content} (%) = \frac{V_{air}}{V_{total}} \times 100 ]

Where:

• ( V_{air} ) = Volume of entrained air

• ( V_{total} ) = Total volume of concrete or mortar

Benefits of Air-Entraining:

• Improves frost resistance by providing space for ice expansion

• Enhances workability without increasing water content

• Reduces bleeding and segregation

flowchart LR
    A[Air-Entraining Agent Added] --> B[Mixing with Cement/Mortar]
    B --> C[Entrained Air Bubbles Formed]
    C --> D[Improved Workability & Frost Resistance]

For detailed dosage and performance, refer to IS 6461 Part 2 tables and test methods for air content measurement.

IS 6461 Part 2 - Air-Entraining Agent: Key Points

• Definition (Clauses 2.5, 2.6, 2.7):

  • Air-Entraining Agent: An admixture added to cement, mortar, or concrete to create microscopic air bubbles.
  • Purpose: Improves workability and enhances frost resistance.
  • Air-Entraining Hydraulic Cement: Cement pre-mixed with air-entraining agent to achieve specified air content.

• Typical Specifications:

  • Air content in fresh concrete/mortar: Usually 4% to 8% by volume for frost resistance.
  • Bubble size: Minute, stable bubbles typically 10 to 100 microns diameter.
  • Dosage: Varies with cement type and desired air content, typically 0.05% to 0.3% by weight of cement.

• Effect on Concrete Properties:

  • Increases workability without extra water.
  • Improves durability against freeze-thaw cycles.
  • Slight reduction in compressive strength (~5-15%) due to air voids.

Typical Formula for Air Content Estimation

[ \text{Air Content (%)} = \frac{\text{Volume of entrained air}}{\text{Total volume of concrete}} \times 100 ]

Summary Table: Air-Entraining Agent Dosage vs Air Content

flowchart LR
    A[Addition of Air-Entraining Agent] --> B[Mixing with Cement/Mortar]
    B --> C[Formation of Microscopic Air Bubbles]
    C --> D[Improved Workability]
    C --> E[Frost Resistance]
    C --> F[Reduced Compressive Strength (minor)]

Note: Always verify air content using standard tests (e.g., pressure method per IS 1199) and adjust dosage accordingly.

IS 6461 Part 2 - Barite in Concrete

• Definition (Clause 2.10):
  Barite (BaSO4) is used as a heavy mineral aggregate in concrete to produce high-density radiation shielding concrete.

• Key Specifications:

  • Purity: Typically used in pure or impure forms.
  • Purpose: To increase density for radiation shielding (e.g., nuclear plants, X-ray rooms).
  • Density: Barite concrete density ranges from 3.5 to 4.0 g/cm³, significantly higher than normal concrete (~2.4 g/cm³).

• Typical Mix Considerations:

  • Replace normal aggregate with barite aggregate.
  • Maintain workability and strength by adjusting water-cement ratio.
  • Ensure compatibility with cement and admixtures.

• Relevant Formula: To estimate the density of barite concrete:

  [ \rho_c = \frac{W_c + W_a}{V_c} ]

  Where:
  (\rho_c) = density of concrete (kg/m³)
  (W_c) = weight of cement + water + admixtures (kg)
  (W_a) = weight of barite aggregate (kg)
  (V_c) = volume of concrete (m³)

• Typical Density Table:

  Aggregate Type	Density (g/cm³)	Application
  Normal Aggregate	~2.6	Standard concrete
  Barite Aggregate	4.2 - 4.5	Radiation shielding concrete

Barite concrete is essential where high-density and radiation shielding properties are required.

flowchart LR
    A[Barite Mineral (BaSO4)] --> B[Barite Aggregate]
    B --> C[High-Density Concrete Mix]
    C --> D[Radiation Shielding Concrete]

Summary: Use Barite as a heavy aggregate to increase concrete density for radiation protection, following IS 6461 Part 2 guidelines.

IS 6461 Part 2 - Breeze (Clause 2.12)

• Definition: Breeze is usually cinder or fine divided material from coke production.
• Use: Commonly used as a lightweight aggregate or filler in concrete and masonry.
• Properties to consider:
  • Particle size: Fine, similar to sand.
  • Specific gravity: Typically lower than sand (~1.8 to 2.0).
  • Bulk density: Lighter than conventional aggregates.
  • Absorption: Higher porosity, so water absorption is significant.

Typical Specifications (General guidelines from related IS codes):

Key Notes:

• Breeze should be free from harmful impurities like clay, dust, and organic matter.
• When used in concrete, adjust mix water due to higher absorption.
• Test for strength and durability as per IS 383 (Coarse and fine aggregates for concrete).

flowchart LR
    Breeze["Breeze (Cinder/Fine Coke Material)"]
    Breeze -->|Used as| LightweightAggregate
    Breeze -->|Properties| ParticleSize[Particle Size < 4.75mm]
    Breeze -->|Properties| SpecificGravity[Specific Gravity ~1.8-2.0]
    Breeze -->|Properties| BulkDensity[Bulk Density 800-1200 kg/m³]
    Breeze -->|Properties| WaterAbsorption[Water Absorption 5-15%]

For detailed mix design and testing, refer IS 383 and IS 456.

IS 6461 Part 2 - Catalyst (Promoter) Summary

• Definition (Clause 2.15):
  Catalyst or Promoter is a substance that accelerates chemical reactions without being consumed.

• Related Terms:

  • Accelerator (Clause 2.1): Speeds up cement hydration, shortens setting time, and enhances early strength.
  • Flow Promoter (Clause 2.22): Added to coatings to improve brushability and leveling.
  • Chemical Hardener (Clause 2.25): Applied to concrete floors to reduce wear/dusting or acts as curing agent in two-component adhesives.

Key Specifications & Usage

Typical Formula for Accelerator Dosage (IS 6461 Reference)

[ \text{Dosage} = 0.5% \text{ to } 2% \text{ by weight of cement} ]

• Adjust dosage based on ambient temperature and desired set time.

flowchart LR
    Catalyst["Catalyst/Promoter"]
    Accelerator["Accelerator"]
    FlowPromoter["Flow Promoter"]
    Hardener["Chemical Hardener"]

    Catalyst --> Accelerator
    Catalyst --> FlowPromoter
    Catalyst --> Hardener

    Accelerator -->|Speeds hydration| Concrete
    FlowPromoter -->|Improves coating| Coating
    Hardener -->|Reduces dusting| ConcreteFloor
    Hardener -->|Cures resin| Adhesive

Summary: Catalysts or promoters in IS 6461 Part 2 primarily accelerate chemical reactions in concrete and coatings without being consumed, improving set time, strength, and surface finish. Dosages and specific chemicals vary with application.

IS 6461 Part 2: Compound, Joint Sealing – Key Points

• Definition (Clauses 2.17 & 2.18):
  Impervious materials used to fill joints or cracks in pavements/structures to prevent ingress of water and debris.

• Types of Compounds:

  • Joint Sealing Compound: Fills expansion/construction joints.
  • Sealing Compound: Coats or fills cracks in concrete/mortar.

• Essential Properties:

  • Impervious to water
  • Elasticity to accommodate joint movement
  • Adhesion to substrate
  • Durability under environmental exposure

• Typical Application Specifications:

  • Joint width: Usually 10-25 mm (varies per design)
  • Depth of sealant: ~1/2 to 2/3 of joint width
  • Backer rod used to control sealant depth and shape

• Common Formulas (for joint sealant volume):
  [ \text{Volume} = \text{Joint Length} \times \text{Joint Width} \times \text{Sealant Depth} ]

• Recommended Sealant Shape:
  Hourglass or concave profile to allow movement and prevent tearing.

Example Table: Joint Sealant Depth vs Width

flowchart LR
    A[Joint Opening] --> B[Backer Rod Placement]
    B --> C[Sealant Application]
    C --> D[Finished Joint Seal]
    D --> E[Waterproof & Elastic Seal]

Summary: IS 6461 Part 2 defines joint sealing compounds as impervious, elastic materials used to fill joints/cracks, ensuring waterproofing and durability. Proper depth, width, and backer rod use are critical for effective sealing.

IS 6461 Part 2: Compound, Sealing & Joint Sealing

Key Definitions:

• Compound, Sealing (2.18): Impervious material coating or filling cracks/joints in concrete or mortar.
• Compound, Joint Sealing (2.17): Impervious material specifically for filling joints in pavements/structures.
• Waterproofing Compound (2.19 & 2.32): Material imparting water repellency to structures.

Typical Specifications & Usage:

Common Formulas/Considerations:

• Joint Width (w): Select sealing compound thickness = 0.25 to 0.5 × w
• Movement Accommodation: Compound must allow ±15% movement of joint width
• Application: Clean, dry joint → Primer (if required) → Sealant → Tooling for smooth finish

Summary Diagram:

flowchart LR
    A[Concrete/Mortar Joint] --> B[Clean & Prepare Joint]
    B --> C[Apply Primer (optional)]
    C --> D[Apply Sealing Compound]
    D --> E[Tool & Cure]
    E --> F[Impervious, Flexible Seal]

Note: For detailed mix proportions, performance tests, and application methods, refer to IS 6461 Part 2 clauses on compound properties and testing.

IS 6461 Part 2: Waterproofing Compounds

Definitions (Clauses 2.17 - 2.19)

• Waterproofing Compound: Material imparting water repellency to structures or units.
• Sealing Compound: Impervious coating/filler for joints or cracks.
• Joint Sealing Compound: Impervious filler specifically for joints in pavements or structures.

Key Specifications:

• Purpose: To prevent water ingress and protect structural integrity.
• Properties: Imperviousness, adhesion, durability, compatibility with concrete/mortar.

Typical Application Guidelines:

• Mixing: Follow manufacturer’s ratio; often liquid compounds mixed with cement or applied as coatings.
• Coverage: Usually specified in kg/m² or liters/m² depending on compound type.
• Thickness: Coating thickness typically ranges from 1 to 3 mm for effective waterproofing.

Common Formulas:

• Waterproofing Compound Dosage:
  [ \text{Compound} = (0.5% \text{ to } 2%) \times \text{weight of cement} ]

• Joint Sealing:
  Use elastic compounds with elongation > 100% and adhesion > 1.5 MPa.

Example Table: Typical Waterproofing Compound Types

flowchart TD
    A[Structure] --> B[Apply Waterproofing Compound]
    B --> C{Type of Compound}
    C --> D[Cement-based]
    C --> E[Bituminous]
    C --> F[Polymer-based]
    D --> G[Mixed with cement]
    E --> H[Surface coating]
    F --> I[Coating or admixture]

Summary: Use waterproofing compounds as per IS 6461 Part 2 definitions, ensuring proper dosage (0.5-2% cement weight), correct application method, and selecting compound type based on structure and exposure.

IS 6461 Part 2 - Flow Promoter Key Points

• Definition (Clause 2.22):
  A Flow Promoter is an additive in coatings that improves brushability, flow, and levelling of the applied material.

• Purpose:
  Enhances smooth application by reducing surface tension and promoting even spread without sagging or brush marks.

• Related Additives:

  • Dispersing Agent (2.20): Improves fluidity by reducing particle attraction.
  • Water-Reducing Agent (2.33): Improves workability without extra water.

Typical Specifications & Effects

General Formula Concept

Flow promoters often contain surfactants or polymers:

[ \text{Flow Promoter} = \text{Surfactant} + \text{Levelling Agent} ]

• Dosage: Usually 0.1% to 1% by weight of coating.

flowchart LR
    A[Coating] --> B[Add Flow Promoter]
    B --> C[Reduced Surface Tension]
    C --> D[Improved Brushability]
    C --> E[Better Flow & Levelling]

Summary: Use flow promoters to achieve smooth, uniform coatings with enhanced application properties as per IS 6461 Part 2 Clause 2.22.

IS 6461 Part 2 - Fluosilicate Overview

• Definition (Clause 2.23):
  Fluosilicate is a salt, typically magnesium or zinc fluosilicate, applied on concrete surfaces as a surface-hardening agent.

• Purpose (Clause 2.25a):
  Used to reduce wear and dusting on concrete floors by chemical treatment.

• Application:

  • Applied as a liquid solution on fresh or cured concrete floors.
  • Reacts chemically with free lime (Ca(OH)₂) in concrete to form insoluble compounds, increasing surface hardness.

Key Chemical Reaction (Simplified):

[ \text{MgSiF}_6 + Ca(OH)_2 \rightarrow \text{Insoluble Silicates} + \text{Other Products} ]

• This reaction densifies the surface, reducing dusting and improving abrasion resistance.

Typical Specifications:

Notes:

• Fluosilicate treatment is not structural but improves durability and service life of concrete floors.
• Should be applied on clean, dry surfaces for best results.

flowchart LR
    A[Concrete Surface] --> B[Application of Fluosilicate Solution]
    B --> C[Chemical Reaction with Free Lime]
    C --> D[Formation of Insoluble Silicates]
    D --> E[Increased Surface Hardness & Reduced Dusting]

For detailed mix proportions and application methods, refer to the Materials Section of IS 6461 Part 2 or relevant manufacturer guidelines.

IS 6461 Part 2 (1972) – Pumice as Lightweight Aggregate

Key Specifications for Pumice (Clause 2.28)

• Nature: Highly porous, vesicular volcanic rock with high silica content.
• Structure: Glassy, fibrous texture with sealed vesicles (air pockets).
• Use: Lightweight aggregate in concrete to reduce density and improve thermal insulation.

Relevant Properties of Concrete with Pumice Aggregate

• Density: Typically 800 to 1600 kg/m³ (much lighter than normal concrete).
• Compressive Strength: Usually lower than normal concrete; depends on pumice quality and mix design.
• Water Absorption: High due to porosity; affects workability and curing.

Design & Mix Guidelines (Generalized from IS and Practice)

Important Formula: Density of Lightweight Concrete

[ \rho_{concrete} = \rho_{cement\ paste} + \rho_{pumice\ aggregate} \times (1 - V_{voids}) ]

Where:

• (\rho) = density (kg/m³)
• (V_{voids}) = volume fraction of voids in aggregate

Summary:

• Pumice is used as a lightweight aggregate to reduce concrete weight.
• High porosity leads to lower strength and higher water absorption.
• Mix design must compensate for water absorption and strength reduction.

flowchart LR
    A[Pumice Aggregate] --> B[High Porosity & Vesicles]
    B --> C[Lightweight Concrete]
    C --> D[Lower Density & Strength]
    C --> E[Improved Thermal Insulation]
    B --> F[High Water Absorption]
    F --> G[Adjust Water-Cement Ratio]

For detailed mix design and testing, refer to IS 6461 Part 2 (1972) and related lightweight concrete standards.

IS 6461 Part 2 - Retarder: Key Points

• Definition (Clause 2.30):
  A Retarder is an admixture that delays the setting time of cement paste, mortar, or concrete.

• Purpose:

  • Extends workability time
  • Prevents premature setting in hot weather or long transport
  • Useful in large pours or complex formworks

• Typical Retarder Types:

  • Lignosulfonates
  • Hydroxycarboxylic acids
  • Sugars and their derivatives

• General Specification:

  • Retarder dosage typically ranges from 0.05% to 0.5% by weight of cement
  • Effectiveness depends on cement type, temperature, and dosage

• Effect on Setting Time:

  • Retarders increase initial and final setting times, measurable by Vicat apparatus (IS 5512)

Typical Influence on Setting Time (Example)

Notes:

• Retarders should not adversely affect ultimate strength.
• Compatibility with other admixtures (water-reducers, accelerators) must be checked.
• IS 6461 Part 2 recommends testing admixtures as per IS 9103 for performance.

flowchart LR
    Cement + Water --> Hydration
    Hydration --> Setting
    Retarder -. delays .-> Setting
    Retarder --> Extended Workability

Summary: Retarders delay cement setting to improve workability time, dosage and effects must be optimized per IS 6461 Part 2 and related standards.

Waterproofed Cement (IS 6461 Part 2)

Definitions:

• Waterproofed Cement (Clause 2.31): Cement interground with water-repellent materials like calcium stearate.
• Water-Repellent Cement (Clause 2.34): Hydraulic cement with added water-repellent agents during manufacture to resist water absorption.

Key Specifications:

Important Notes:

• The waterproofing compound (Clause 2.32) is a material used to impart water repellency to structures.
• Water-repellent cement is manufactured by adding agents during grinding to improve resistance to water ingress.

Typical Use:

• Ideal for foundations, basements, water tanks, and damp-prone areas.
• Enhances durability by reducing permeability.

Conceptual Diagram:

flowchart LR
    Cement -->|Add water-repellent agent| Waterproofed_Cement
    Waterproofed_Cement -->|Mix with water + aggregates| Concrete
    Concrete -->|Reduced water absorption| Durable_Structure

For detailed mix proportions or performance tables, refer to IS 6461 Part 2 full text or manufacturer datasheets.

IS 6461 Part 2 - Water-Reducing Agent Key Points

• Definition (Clause 2.33):
  A water-reducing agent improves workability of fresh mortar/concrete without extra water or maintains workability with less water.

• Purpose:

  • Enhances fluidity
  • Reduces water-cement ratio → increases strength and durability
  • Improves compaction and finish

Typical Specifications & Effects

Basic Formula for Water Reduction Impact

[ W_{new} = W_{original} \times (1 - \frac{% \text{water reduction}}{100}) ]

Where,

• ( W_{new} ) = Reduced water content
• ( W_{original} ) = Original water content

Related Admixtures (for context)

flowchart LR
    A[Water-Reducing Agent] --> B[Reduces Water Content]
    B --> C[Improves Workability]
    B --> D[Increases Strength]
    A --> E[Maintains Workability with Less Water]

Summary: Use water-reducing agents to lower water content by 5-20%, improving concrete strength and workability without compromising setting time.