Glossary of terms relating to building lime

IS 6508: Scope Summary

• Title: Glossary of Terms Relating to Building Lime (First Revision)
• Purpose: Defines precise and additional technical terms used in lime and lime-based construction products.
• Scope:
  • Covers terminology related to building lime and lime-based materials.
  • Supports clarity and uniformity in communication within the construction industry.
  • Does not include design or material specifications but focuses on definitions.

Key Points:

Note: IS 6508 is a glossary standard; it does not provide formulas or design tables but standardizes terminology for lime products.

flowchart LR
    A[Building Lime Products] --> B[Technical Terms]
    B --> C[Definitions per IS 6508]
    C --> D[Uniform Communication]
    C --> E[Standardized Terminology]

For formulas or specifications, refer to other IS codes like IS 712 (Hydrated Lime) or IS 6932 (Lime Mortars).

IS 6508: Definitions of Terms for Building Lime

IS 6508 provides a glossary of terms related to building lime, ensuring clarity and uniformity in usage. Though it does not contain formulas or tables, it standardizes terminology frequently used in lime construction.

Key Definitions (Examples):

• Hydrated Lime: Lime that has been slaked by the addition of water, resulting in calcium hydroxide.
• Quicklime: Calcium oxide obtained by calcining limestone.
• Fat Lime: Lime with high calcium content and high reactivity.
• Hydraulic Lime: Lime that sets by reacting with water and also hardens under water.
• Non-Hydraulic Lime: Lime that sets only by carbonation (reaction with CO₂ in air).

Usage:

• This glossary aids engineers and builders in consistent communication.
• It complements other IS standards on lime products.

Summary Table of Common Lime Types

flowchart LR
    Quicklime -->|Add Water| HydratedLime
    HydratedLime -->|Carbonation| SetLime
    HydraulicLime -->|Sets in water| SetLime
    NonHydraulicLime -->|Sets in air| SetLime

For detailed definitions, refer directly to IS 6508 glossary section.

IS 6508: Air-Slaked Lime - Key Points & Formulas

Definitions (from IS 6508)

• Air-Slaked Lime (Clause 2.1): Contains oxides, hydroxides, and carbonates of Ca and Mg formed by exposing quicklime to air.
• Available Lime (Clause 2.4): Total reactive lime (quick + hydrated) under specific conditions.
• Slaked Lime (Clause 2.69): Lime obtained by controlled slaking of quicklime.

Key Specifications for Air-Slaked Lime

• Chemical Composition:
  • CaO (free lime)
  • Ca(OH)₂ (slaked lime)
  • CaCO₃ (carbonate formed by air exposure)
• Physical Properties:
  • Fineness: Should pass 90% through 90-micron sieve
  • Moisture content: Typically < 5%
• Available Lime:
  [ \text{Available Lime} = \text{CaO (free)} + \text{Ca(OH)}_2 ]

Typical Chemical Analysis Table (Example)

Important Notes

• Air-slaked lime is less reactive than freshly slaked lime due to carbonate presence.
• Used mainly in soil stabilization, mortar, and as a chemical reagent.
• Quality control involves testing for available lime and fineness.

flowchart LR
    Quicklime -->|Excess Air Exposure| Air-Slaked Lime
    Quicklime -->|Controlled Slaking| Slaked Lime
    Air-Slaked Lime -->|Contains| CaO & Ca(OH)2 & CaCO3
    Slaked Lime -->|Contains| Ca(OH)2

For detailed testing procedures and limits, refer to IS 6508 clauses on chemical and physical requirements.

IS 6508 - Autoclaved Lime: Key Points & Specifications

• Definition (Clause 2.2):
  Autoclaved lime is dolomitic lime that has undergone pressure hydration in an autoclave, enhancing its reactivity and suitability for structural use.

• Properties:

  • Contains both CaO and MgO phases.
  • Improved strength and durability due to autoclaving.
  • Higher Available Lime (Clause 2.4), crucial for reaction efficiency.

• Key Specifications:

  • Available Lime Content: Typically > 70% (reactive lime content).
  • Fineness: Should pass IS sieve No. 90 (0.177 mm) at least 90%.
  • Moisture Content: Usually < 2%.
  • Loss on Ignition (LOI): Controlled to ensure minimal impurities.

• Usage:
  Mainly in lime mortars, plasters, and soil stabilization where enhanced strength and durability are needed.

Typical Chemical Composition (approximate)

Reaction Concept (Available Lime)

[ \text{Available Lime} = \text{CaO (free + combined)} + \text{MgO (free + combined)} ]

This lime reacts with water and CO2 to form stable calcium/magnesium carbonates, providing strength.

flowchart LR
    QuickLime -->|Autoclave Hydration| AutoclavedLime
    AutoclavedLime -->|High Reactivity| StructuralUse
    StructuralUse --> Mortars
    StructuralUse --> SoilStabilization

For detailed testing methods and limits, refer to IS 6508 clauses on chemical and physical requirements.

Autogenous Healing in Lime Mortars (IS 6508)

Autogenous healing is a self-repair mechanism in lime mortars where calcium carbonate (CaCO₃) forms by carbonation of hydrated lime (Ca(OH)₂) when exposed to atmospheric CO₂. This process fills minor cracks and pores, enhancing durability.

Key Points from IS 6508:

• Mechanism:
  [ \text{Ca(OH)}_2 + \text{CO}_2 \rightarrow \text{CaCO}_3 + \text{H}_2\text{O} ]
• Effect: Bridges minor cracks and air voids at masonry joints.
• Materials: Lime mortar = lime + fine aggregate + water (Clause 2.34).
• Hydraulic Lime: Contains reactive silica/alumina, sets by hydration and carbonation (Clauses 2.24, 2.18, 2.65).

Practical Specifications:

Notes:

• Ensure adequate moisture and CO₂ exposure for effective healing.
• Use non-hydraulic or weakly hydraulic lime for better autogenous healing.
• Lime-cement mortars (Clause 2.35) reduce healing due to cement dominance.

flowchart LR
    A[Hydrated Lime Ca(OH)2] -->|Absorbs CO2| B[Calcium Carbonate CaCO3]
    B --> C[Bridges Cracks & Voids]
    C --> D[Improved Durability & Strength]

This natural healing improves masonry longevity without external repair.

IS 6508 - Calcination Zone Key Points

• Definition (Clause 2.8):
  The Calcination Zone is the middle section of the kiln where limestone (CaCO₃) is thermally decomposed into lime (CaO) and CO₂.

• Process:

  • Limestone is heated to ~900–1000°C.
  • Reaction:
    [ \text{CaCO}_3 \xrightarrow{\Delta} \text{CaO} + \text{CO}_2 \uparrow ]

• Temperature Range:

  • Calcination typically occurs between 900°C to 1100°C.

• Zones in Kiln (for clarity):

  graph TD
    A[Preheating Zone - Top] --> B[Calcination Zone - Middle]
    B --> C[Cooling Zone - Bottom]
  

• Design Considerations:

  • Adequate residence time for complete calcination.
  • Proper gas flow to remove CO₂ and supply heat.
  • Kiln length and inclination affect zone length.

• Typical Parameters:

  Parameter	Value/Range
  Temperature	900 - 1100 °C
  Residence Time	30 to 60 minutes (approx)
  Limestone Feed Size	20 - 40 mm (typical)

• IS 6508 Reference:
  While IS 6508 defines zones, detailed thermal calculations and kiln design are covered in IS 6932 and IS 6933 for lime kilns.

For detailed kiln design, consult IS 6932 (Lime Kilns) for heat balance and dimensioning formulas.

IS 6508 - Charge Specifications & Key Definitions

1. Charge (Clause 2.10)

• Charge = Limestone, limeshell, other calcareous materials + fuel (for mixed feed kiln).
• It is the raw material fed into the kiln for lime production.

2. Particle Size (Clause 6.3)

• Ground, Screened or Granular: Particles < 6.3 mm.
• Powdered: Particles passing through 850 micron IS sieve (substantially all).

3. Available Lime (Clause 2.4)

• Total lime (CaO) in quick/hydrated lime that reacts under specified conditions.
• Important for assessing lime quality and reactivity.

4. Volume Yield of Quicklime (Clause 2.76)

• Volume of putty (standard consistency) obtained per unit mass of quicklime.
• Indicates the expansion and hydration capacity of quicklime.

Summary Table

flowchart LR
    Charge -->|Feed into kiln| Kiln
    Kiln --> Quicklime
    Quicklime -->|Hydrate| Putty
    Putty --> Volume Yield (per unit mass)

Use these specs for quality control and process optimization in lime manufacturing per IS 6508.

IS 6508: Cooling Zone in Lime Kilns

• Definition (Clause 2.14):
  The Cooling Zone is the bottom portion of the kiln where burnt lime is cooled by the incoming air needed for fuel combustion.

• Function:

  • Cools the calcined lime to a manageable temperature.
  • Preheats the combustion air, improving fuel efficiency.

• Key Parameters:

  • Cooling air temperature rise (ΔT)
  • Heat transfer rate from lime to air
  • Air flow rate for sufficient cooling and combustion

• Typical Heat Balance Formula:
  [ Q = m_{air} \times C_p \times \Delta T = m_{lime} \times C_{lime} \times \Delta T_{lime} ] Where:

  • (m_{air}) = mass flow rate of cooling air
  • (C_p) = specific heat of air (~1.005 kJ/kg·K)
  • (\Delta T) = temperature rise of air
  • (m_{lime}) = mass flow rate of burnt lime
  • (C_{lime}) = specific heat of lime (~0.84 kJ/kg·K)
  • (\Delta T_{lime}) = temperature drop of lime

• Specification Notes:

  • Cooling zone length depends on kiln size and airflow.
  • Steel-shell kilns (Clause 2.72) require careful thermal design due to steel's thermal conductivity.

Simplified Cooling Zone Heat Exchange Diagram

flowchart LR
    Lime_in[Burnt Lime (Hot)] -->|Heat Transfer| Cooling_Zone
    Cooling_Zone --> Lime_out[Cooled Lime]
    Air_in[Incoming Air (Cold)] -->|Absorbs Heat| Cooling_Zone
    Cooling_Zone --> Air_out[Heated Air]

For detailed dimensioning, refer to kiln-specific design tables in IS 6508 or related thermal engineering references.

IS 6508 - Core (Calcined Lump Lime)

• Definition (Clause 2.15):
  The Core is the central unburnt portion of the calcined lump lime. It indicates incomplete calcination.

• Specifications:

  • Core presence should be minimal for quality lime.
  • No direct formula is provided in IS 6508 for core size or quantity.

• Particle Size Classification (Clause 6.3):

  • Ground, Screened or Granular: Particles less than 6.3 mm.
  • Powdered: Passing through 850 micron IS Sieve.

Practical Notes:

• The core affects lime reactivity; larger cores reduce effectiveness.
• Testing involves breaking lumps and visually inspecting or weighing the unburnt core.

Summary Table:

flowchart LR
    Lump_Lime -->|Calcined| Calcined_Lump
    Calcined_Lump -->|Central portion| Core[Unburnt Core]
    Calcined_Lump -->|Outer portion| Burnt_Lime

Key: Minimize core for high-quality lime per IS 6508.

IS 6508: Dead Burnt Lime (Hard-Burnt / Over-Burnt Lime)

Key Definitions (Clauses 2.16, 2.22, 2.53)

• Dead Burnt Lime: Lime burnt to a stage where it is predominantly non-reactive.
• Also called Hard-Burnt Lime or Over-Burnt Lime.
• Characterized by low reactivity and minimal slaking.

Specifications & Properties

• Chemical Composition: Mainly CaO with low free CaO reactivity.
• Physical Form: Dense, hard lumps or powder.
• Reactivity: Very low compared to quicklime (highly reactive CaO).
• Used where slow or no slaking is desired.

Typical Use & Testing (from general practice)

Important Notes:

• Dead burnt lime is not suitable for applications requiring rapid slaking.
• Used in refractory, chemical industries, or where inert lime is needed.

flowchart LR
    A[Quicklime (CaO)] --> B[Burning Process]
    B --> C{Burning Intensity}
    C -->|Normal| D[Quicklime (Reactive)]
    C -->|Excessive| E[Dead Burnt Lime (Non-reactive)]
    E --> F[Hard lumps, low reactivity]

For detailed chemical and physical tests, refer to IS 6508 clauses on lime testing methods.

IS 6508 - Fat Lime Key Points

• Definition (Clause 2.20):
  Fat Lime is a pure non-hydraulic lime with a minimum of 79% CaO (Calcium Oxide) on an ignited basis.

• Available Lime (Clause 2.4):
  Total lime in quick and hydrated form that reacts under specified conditions.

Specifications for Fat Lime:

Important Formulas:

• Available Lime (%) = % Quicklime + % Hydrated Lime that reacts under test conditions.

• CaO Content (ignited basis) is determined by heating the lime to drive off CO₂ and moisture, then measuring CaO.

Notes:

• Fat Lime is used where high purity lime is required (e.g., chemical industries, soil stabilization).

• Different from hydraulic lime, which contains silicates and aluminates.

flowchart LR
    A[Quicklime (CaO)] --> B[Slaking] --> C[Hydrated Lime (Ca(OH)₂)]
    B --> D[Fat Lime (Non-hydraulic)]
    C --> D
    D --> E[Available Lime in Reaction]

Summary: Fat Lime per IS 6508 is a high-purity lime with ≥79% CaO, used where non-hydraulic lime is essential. Available Lime includes quicklime and hydrated lime reactive under conditions.

IS 6508: Hydrated Hydraulic Lime Key Points

Definitions:

• Hydrated Hydraulic Lime (Clause 2.25): Lime obtained by hydrating Class A, B, and E lime, containing hydraulic components (lime + silica, alumina, iron hydroxides).
• Hydraulic Lime (2.24): Lime capable of setting under water.
• Eminently Hydraulic Lime (2.18): Lime with calcium compounds of silica, alumina, iron oxide that react with water to gain strength.

Key Specifications & Properties:

• Chemical Composition: Contains Ca(OH)₂ + reactive silica (SiO₂), alumina (Al₂O₃), iron oxide (Fe₂O₃).
• Setting Reaction: Hydraulic components react with water → strength-giving calcium silicate hydrates (CSH).
• Classes: Class A, B, E based on hydraulicity and composition.

Typical Formula for Hydration:

[ CaO + H_2O \rightarrow Ca(OH)_2 ]

Hydraulic reaction (simplified): [ Ca(OH)_2 + SiO_2 + Al_2O_3 + Fe_2O_3 + H_2O \rightarrow CSH + strength \ compounds ]

Typical Properties Table (Indicative):

Summary:

Hydrated Hydraulic Lime is a chemically reactive lime with hydraulic properties, setting under water due to its calcium silicate and aluminate phases. It is used in masonry, plaster, and mortars where moderate strength and durability are required.

flowchart LR
    Quicklime(CaO) -->|Hydration| Hydrated_Lime(Ca(OH)₂)
    Hydrated_Lime -->|With Silica, Alumina, Iron Oxide| Hydraulic_Lime
    Hydraulic_Lime -->|Reaction with Water| Strength_Giving_Compounds(CSH)

For detailed mix design and testing, refer to IS 6508

IS 6508: Kiln Dust - Key Points

• Definition (Clause 2.28):
  Kiln dust is the dust collected from the bottom of the kiln, typically containing coal ash, air-slaked lime, and unslaked lime dust in mixed-feed kilns.

• Related Terms:

  • Run-of-Kiln Quicklime (2.61): Quicklime discharged directly from the kiln, often containing impurities.
  • Charge (2.10): Raw materials (limestone, limeshell, fuel) fed into the kiln.

Specifications & Usage:

• Kiln dust is generally considered a by-product with variable chemical composition.
• It may be recycled or disposed of depending on its chemical and physical properties.
• Its lime content influences its suitability for soil stabilization or cement manufacturing.

Typical Chemical Composition (approximate for kiln dust):

Important Notes:

• Kiln dust's fineness and chemical reactivity affect its use in construction materials.
• It should be tested for free lime content and carbon content before use.

flowchart LR
    Charge --> Kiln
    Kiln --> Run-of-Kiln Quicklime
    Kiln --> Kiln Dust
    Kiln Dust --> Recycle/Disposal

For detailed design or testing procedures, refer to IS 6508 clauses on lime quality and kiln operations.

IS 6508 - Lime Soil Stabilization: Key Points

Definitions (Clauses)

• Lime Soil Stabilization (2.44): Adding lime to soil to improve strength, durability, commonly for roads.
• Available Lime (2.4): Total lime (quick + hydrated) reactive under specified conditions.
• Lime Slurry (2.43): Hydrated lime suspended in water, cream-like consistency.

Key Specifications & Guidelines

• Lime Content: Typically 3% to 8% by weight of dry soil, depending on soil type.
• Application Forms: Quicklime, hydrated lime, or lime slurry.
• Reaction Time: Allow 7 to 28 days curing for strength gain.

Important Formulas

1. Lime Requirement (%)
   [ \text{Lime Content} = \frac{\text{Weight of Lime}}{\text{Weight of Dry Soil}} \times 100 ]

2. Plasticity Index Reduction
   Lime reduces plasticity index (PI) significantly, improving workability.

Typical Effects of Lime on Soil Properties

flowchart LR
    Soil -->|Add Lime| Lime_Soil_Stabilization
    Lime_Soil_Stabilization -->|Reaction Time| Strength_Improvement
    Lime_Soil_Stabilization --> Plasticity_Reduction
    Lime_Soil_Stabilization --> Durability_Improvement

Summary: IS 6508 defines lime soil stabilization as adding lime (3-8%) to soil to enhance engineering properties, using available lime forms (quick/hydrated/slurry), with curing for strength development.

IS 6508 - NEERU Finish Summary

Definition (Clause 2.52)

• NEERU Finish: A fine lime putty coat applied with or without additives, rubbed and polished to a smooth, even surface.
• Uses Finishing Lime (Clause 2.21): Refined hydrated lime ideal for plaster finishing.

Key Specifications

• Lime putty should be well-aged (typically 3-6 months) for plasticity.
• Additives (optional) may include natural gums or oils to enhance workability and finish.
• Application thickness: Usually 1.5 to 3 mm for the finishing coat.
• Surface is rubbed with a smooth stone or trowel for polishing.

Typical Mix Proportions

Application Steps

1. Prepare surface with a base coat of lime plaster.
2. Apply NEERU finish coat (lime putty ± additives).
3. Rub and polish while still plastic for smoothness.

Related IS Code References

• IS 712: Specification for hydrated lime.
• IS 1661: Lime putty preparation.
• IS 269: Portland cement for base coats if mixed.

flowchart TD
    A[Surface Preparation] --> B[Base Coat of Lime Plaster]
    B --> C[Apply NEERU Finish (Lime Putty ± Additives)]
    C --> D[Rub & Polish to Smooth Finish]
    D --> E[Final Smooth Lime Finish]

Note: NEERU finish is breathable, aesthetically pleasing, and suitable for heritage and traditional buildings. It requires skilled workmanship for best results.

IS 6508 - White Wash: Key Specifications and Formulas

Definition (Clause 2.78)

• White Wash: A paint-like coating made by mixing hydrated lime (slaked quicklime), water, and sometimes other materials.

Typical Mix Proportions

• Hydrated lime : Water = 1 : 3 to 1 : 4 by volume.
• Optional additives: salt, bleaching powder, or natural pigments for improved durability and whiteness.

Preparation Steps

1. Slaking quicklime: Quicklime + water → Hydrated lime (lime putty).
2. Mixing: Lime putty diluted with water to desired consistency.
3. Additives: Added for better adhesion, color, or antiseptic properties.

Important Parameters

Notes

• Ensure hydrated lime is fresh for best results.
• White wash is breathable and antiseptic, suitable for masonry surfaces.

flowchart LR
    QL[Quicklime (CaO)] -->|Add Water| HL[Hydrated Lime (Ca(OH)₂)]
    HL -->|Mix with Water + Additives| WW[White Wash]
    WW -->|Apply on Surface| Surface[Masonry Surface]

For detailed mix design and application, refer to IS 6508 full text and related lime standards.