Code of practice for preparation and use of lime concrete

IS 2541: Scope & Key Specifications

1. Scope Overview

• Covers preparation, testing, and use of lime concrete.
• Materials and proportions must match those used in actual work (Clause 2.1).
• Test specimens are frustum cones with:
  • Bottom diameter: 200 mm
  • Top diameter: 100 mm
  • Height: 300 mm (Clause 4.1.1)

2. Mix Proportions (Clause 5.3)

• Refer to Table 1 (not fully provided) for guidance on mix proportions for various purposes.
• Mix must be consistent with field conditions.

3. Curing (Clause 7.3.2)

• Continuous curing for at least 21 days.
• Follow curing methods as per Clause 7.2.5.

4. Referenced Indian Standards (Annex A)

Specimen Mould Dimensions

graph TD
A[Frustum Cone Specimen] --> B[Bottom Diameter: 200 mm]
A --> C[Top Diameter: 100 mm]
A --> D[Height: 300 mm]

Summary:

• Use materials and proportions identical to site.
• Prepare frustum cone specimens as per dimensions.
• Cure specimens continuously for 21 days.
• Refer to IS codes listed for material specifications and mix design.

IS 2541: Key Formulas, Tables & Specifications for Materials

1. Materials & Proportions (Clause 2.1 & 5.3)

• Use materials and proportions similar to those in actual work.
• Water content in test mix should be as close as possible to site usage.
• Refer Table 1 (Clause 5.3) for mix proportions based on purpose (not provided in excerpt).

2. Curing (Clause 7.3.2)

• Continuous curing for at least 21 days is mandatory.
• Follow curing method as per Clause 7.2.5.

3. Referenced Indian Standards (Annex A)

4. Flexural Strength Formula (Clause 4.2 & Annex C)

For a specimen with span length ( l = 150 , mm ):

[ f_b = \frac{P \times a}{b \times d^2} \quad \text{if } a > 200 , mm ]

[ f_b = \frac{3P \times a}{b \times d^2} \quad \text{if } 170 < a < 200 , mm ]

Where:

• ( f_b ) = Modulus of rupture (N/mm²)
• ( P ) = Maximum load (N)
• ( a ) = Distance from fracture line to nearest support (mm)
• ( b ) = Width of specimen (mm)
• ( d ) = Depth of specimen at failure (mm)

Summary

• Use standardized materials per IS references.
• Maintain water content close to site conditions.
• Cure specimens minimum 21 days.
• Use flexural strength formulas for testing.

flowchart LR
    A[Materials Selection] --> B[Mix Proport

Mortar for Concrete - IS 2541 Key Points

1. Types of Mortar (Clause 6.1.1)

• Plain lime mortar
• Lime-pozzolana mortar
• Lime-cement mortar

Lime must be used as dry hydrated lime or lime putty (per IS 1635:1975). Mortar preparation follows IS 2250:1981.

2. Recommended Mortar Mix Proportions (Table 1, Clause 7.2.1)

• Mortar volume to coarse aggregate volume ratio: 40 to 50 parts mortar per 100 parts aggregate depending on grading.
• Use well-graded aggregates for better workability.
• Slump: 50–75 mm recommended (Annex B).

3. Workability (Clause 5.4)

• Lime mortar has excellent water retention.
• Workability improves with higher lime mortar proportion (within limits) and well-graded aggregates.

Summary Formula for Mortar Mix Proportions:

[ \text{Mortar Mix} = \text{Lime} : \text{Pozzolanic Material (optional)} : \text{Fine Aggregate} ]

Example:
**1 lime : 1 pozzolana : 1

IS 2541: Aggregates Key Points

1. Fine Aggregate (Clause 4.5)

• Should be clean, free from clay lumps, organic impurities.
• Brick aggregate must conform to IS 3182:1986.
• Proper grading and cleanliness ensure good concrete quality.

2. Coarse Aggregate (Clause 6.2)

• Must be washed if containing excessive dirt.
• Porous aggregates (burnt clay, cinder) must be soaked and used in saturated surface dry (SSD) condition.
• Soaking procedure:
  • Soak for 24 hours at 27° ± 2°C.
  • Drain excess water for 2-3 hours before testing or use.

3. Testing Conditions (Clause 2.2)

• Materials brought to room temperature 27° ± 2°C before testing.
• Coarse aggregate soaked in water at room temperature for 24 h.
• Excess water drained for 2-3 h to reach SSD condition.

Typical Specifications Summary:

flowchart TD
    A[Coarse Aggregate] --> B{Excessive Dirt?}
    B -- Yes --> C[Wash Aggregate]
    B -- No --> D[Soak Aggregate]
    D --> E[24 hours at 27° ± 2°C]
    E --> F[Drain 2-3 hours]
    F --> G[Use in SSD Condition]

This ensures proper moisture condition and cleanliness for durable concrete.

IS 2541: Mix Proportions and Strength Requirements for Lime Concrete

1. Mix Proportions (Clause 5.3 & Table 1)

• Note: For lime putty, proportions consider equivalent dry slaked lime.
• Slump for workability: 50 to 75 mm (Annex B).

2. Strength Requirements (Clause 5.6.2)

Key Specifications & Formulas for Preparation of Lime Concrete (IS 2541)

1. Strength Requirements (Clause 5.6.2):

• Compressive strength: ≥ 1 N/mm² at 28 days
• Transverse strength: 0–2 N/mm² at 90 days
• Compressive strength at 90 days: ~1.2 N/mm²

2. Lime Concrete Mix Proportions (Table 1, Clause 7.2.1):

3. Lime Specifications:

• Lime shall conform to IS 712:1984 (Classes A to E).
• When lime is used as putty, proportion by equivalent dry slaked lime.

4. Workability:

• Slump of 50 to 75 mm (Annex B) is generally suitable.

5. Important Notes:

• Adjust mix based on moisture condition, sub-soil water level, and foundation load (Clause 5.2).
• Use stone or broken brick as coarse aggregate depending on availability.

Summary Formula for Mix Ratio by Volume:

IS 2541: Key Points on Laying, Compaction, and Curing of Lime Concrete

1. Laying & Layer Thickness

• Concrete layers should not exceed 100 mm thickness (Clause 7.3.1).
• Alternatively, layers up to 150 mm thickness allowed if consolidated well (Clause 7.2.2).
• Concrete must be laid carefully, avoiding dropping from height to prevent segregation.

2. Compaction

• Continue ramming until wet mortar appears on the surface of the layer.
• Use manual ramming or mechanical means like duty plate or surface vibrators for uniform compaction.
• Ensure no contamination (leaves, dirt, etc.) during laying and compaction.

3. Sub-grade Preparation

• Soil sub-grade must be wetted and rammed properly before laying concrete (Clause 7.2.1).

4. Curing

• Continuous curing for at least 21 days (Clause 7.3.2).
• Follow curing methods as per Clause 7.2.5 (generally water curing or moist covering).

Summary Table: Layer Thickness & Compaction

Visual Concept: Laying & Compaction Process

flowchart TD
    A[Prepare Soil Sub-grade] --> B[Wet & Ram Soil]
    B --> C[Lay Concrete Layer (≤100 mm)]
    C --> D[Compact Layer (Manual/Mechanical)]
    D --> E{Wet Mortar Appears?}
    E -- Yes --> F[Lay Next Layer or Cure]
    E -- No --> D
    F --> G[Cure for 21 Days]

For mix proportions, refer to Table 1 of IS 2541 (not provided here). Also, use referenced IS codes (e.g., IS 269, IS 383) for material specifications.

IS 2541: Use of Lime Concrete in Foundations and Floors

Key Points from Clauses 5.1, 5.2 & 7.2:

• Applications:

  • Levelling course for foundations and plain concrete footings.
  • Base concrete under floors.
  • Filling haunches over masonry arches.

• Selection Criteria (Clause 5.2):

  • Moisture condition of sub-grade.
  • Sub-soil water level.
  • Foundation/floor loads.
  • Type of floor finish (for floors).

Recommended Lime Concrete Mixes (Table 5.4 - Clause 7.2.1):

Additional Notes:

• Use lime putty proportion equivalent to dry slaked lime.
• Workability: Slump of 50 to 75 mm is recommended.
• Fine aggregate details per Clause 4.5.
• Adjust mix based on moisture and load conditions.

Summary

Use of Lime Concrete in Haunches of Arches (IS 2541 - Clause 7.3)

Key Specifications:

• Lime concrete is recommended for filling over haunches of masonry arch work.
• Typical mix proportion (by volume) for haunch filling:
  • 1 lime : 1 pozzolanic material : 1 fine aggregate
• Coarse aggregate: Broken brick, max size 25 mm.
• Mortar to coarse aggregate ratio: 45 parts mortar : 100 parts coarse aggregate.
• Aggregate grading and workability: Slump of 50 to 75 mm (see Annex B).

Strength Requirements (Clause 5.6.2):

Notes:

• Lime class as per IS 712 (B, C, D, E) suitable for these mixes.
• Use dry slaked lime or lime putty with equivalent dry lime content.
• Suitable for arch haunches where moderate strength and durability are required.

Summary Table for Lime Concrete Mix in Haunches

flowchart LR
    A[Lime Concrete Mix] --> B[1 Lime]
    A --> C[1 Pozzolanic Material]
    A --> D[1 Fine Aggregate]
    E[Coarse Aggregate] --> F[Broken Brick, 25 mm max]
    G[Mix Ratio] --> H[45 parts Mortar : 100 parts Coarse Aggregate]
    I[Strength] --> J[≥ 1 N/mm² at 28

IS 2541: List of Referred Indian Standards (Annex A)

This standard on lime concrete refers to key Indian Standards for materials and practices:

Notes:

• Lime concrete durability and sulfate resistance are emphasized.
• Ordinary Portland Cement grades (33, 43, 53) as per IS 269, 8112, 12269.
• Pulverized fuel ash as per IS 15648 is used in lime-pozzolana mixtures.
• The referred standards cover materials, preparation, and testing methods essential for lime concrete.

Key Formula for Flexural Strength (Modulus of Rupture) from IS 2541 Clause 4.2:

[ f_b = \frac{P \times a}{b \times d^2} \quad \text{for } a > 200 \text{ mm (span = 150 mm specimen)} ]

[ f_b = \frac{3P \times a}{b \times d^2} \quad \text{for } 170 < a < 200 \text{ mm} ]

Where:

• ( f_b ) = flexural strength (N/mm²)
• ( P ) =

IS 2541: Method of Test for Determination of Compressive Strength (Clause 5.6.2, Annex B)

Key Specifications:

• Specimen: Lime concrete cubes (cast as per lab-controlled conditions).
• Size: As per mix design; typical cubes.
• Testing Machine:
  • Capacity: Sufficient for max load.
  • Accuracy: ±2% max load error.
  • Platens: Two steel bearing platens with hardened faces; one with spherical seating to ensure uniform load distribution.
  • Bearing face flatness: ≤ 0.01 mm deviation when new, maintained within 0.02 mm.

Test Procedure:

• Clean bearing surfaces and specimen faces.
• Place specimen so load is applied on opposite vertical sides (not top-bottom).
• Align specimen axis with center of thrust of spherical platen.
• Apply load continuously at 10 ± 5 N/mm²/min.
• Record maximum load at failure.
• Note failure type and specimen appearance.

Calculation of Compressive Strength:

[ f_c = \frac{P_{\max}}{A} ]

• (f_c): Compressive strength (N/mm²)
• (P_{\max}): Maximum load applied (N)
• (A): Cross-sectional area (mm²), from mean dimensions

Express strength to nearest 0.1 N/mm².

Acceptance Criteria:

• Average of 3 specimens taken as batch strength.
• Individual results must be within ±15% of average; otherwise, retest.

Summary Table:

flowchart TD
    A[Prepare Specimens] --> B[Clean Platens & Specimen Faces]
    B --> C[Place Specimen Vertically]
    C --> D[Align Axis with Spherical Platen Center]
    D --> E[Apply Load at 10±5 N/mm²/min]
    E

IS 2541: Method of Test for Determination of Transverse Strength

Specimen Preparation & Size (Clause C-1, C-2)

• Specimen size: 150 mm × 150 mm × 700 mm
• Preparation & curing same as compression test specimens (Clauses B-1 to B-7)
• Store specimens in water at 27°C ± 2°C for 22 hours before testing

Test Setup (Clause C-2, C-4.2)

• Support span: 600 mm between two steel rollers (38 mm diameter)
• Loading rollers: two rollers spaced 200 mm apart at third points of the span
• Load applied axially without torsion or restraints
• Load rate: Increase so that extreme fiber stress rises at approx. 0.7 N/mm²/min or 4000 N/min
• No packing between specimen and rollers; clean contact surfaces

Calculation of Flexural Strength (Modulus of Rupture, fb) (Clause C-5)

Let:

• P = Maximum load (N)
• b = Width of specimen (mm)
• d = Depth of specimen at failure (mm)
• a = Distance from fracture line to nearest support (mm)
• l = Span length = 600 mm

Summary Table of Parameters

Diagram: Test Setup