Method of test for building limes, Part VII: Determination of compressive and transverse strength

IS 6932 Part 7 (1973) - Introduction and Adoption: Key Points

• Adoption Date: Adopted on 22 March 1973 by Indian Standards Institution.
• Scope: Methods of tests for building limes.
• Referenced Standards Updates:
  • IS 2250:1981 replaces IS 1625:1971 for masonry mortar preparation.
  • IS 712:1984 replaces IS 712-1964 for building lime specifications.
  • IS 1070:1992 replaces IS 1070-1960 for reagent grade water.
  • IS 650:1991 replaces IS 650-1971 for building lime specifications.
  • IS 460 (Part 1):1985 replaces IS 460-1962 for test sieves.
• Test Specimen Preparation: Follow IS 2250:1981 code of practice.
• Evaluation and Reporting: Results should be rounded per IS 2:1960.
• Footnotes: Updated to reflect current codes for mortar preparation, reagent water, and sieves.

Summary Table of Key Replacements

Reporting of Test Results

• Round off values as per IS 2:1960 (Rules for rounding off numerical values).

flowchart TD
    A[Start: Lime Sample] --> B[Prepare Test Specimen (IS 2250:1981)]
    B --> C[Test Procedures (IS 6932 Part 7

IS 6932 Part 7 (1973) - Preparation of Sample for Lime Testing

Key Specifications & Steps:

• Sample Size & Crushing

  • Use ~1 kg of quicklime.
  • Crush to pass through 2.36 mm IS Sieve (IS:460-1962).

• Slaking

  • Slake isothermally for 1 hour as per IS 6932 Part III (2.3).
  • Stir resulting putty with wooden rod.

• Sieving & Water Content Adjustment

  • Sieve putty through 850 micron IS Sieve.
  • Collect on filter cloth; remove excess water by hand pressing.
  • Target water content: 60-65% by mass of dry hydrated lime.
  • Adjust water by drying on absorbent surface or adding water if too dry.

Moisture Determination (Clause 3.1.4)

• Dry weighed portion at 100 ±10°C until constant weight.
• Mass loss should be 60-65% of dry residue mass (due to CO₂ absorption).

Summary Table

flowchart TD
    A[Quicklime Sample ~1kg] --> B[Crush to pass 2.36mm sieve]
    B --> C[Slake isothermally for 1 hour]
    C --> D[Stir putty with wooden rod]
    D --> E[Sieve putty through 850 micron sieve]
    E --> F[Collect on filter cloth & press]
    F --> G[Adjust water content to 60-65%]
    G --> H[Ready for testing]

This procedure ensures uniform sample preparation for consistent lime testing results as per IS 6932 (Part 7).

Use of Distilled Water as per IS 6932 Part 7 (1973)

• Clause 2.2: Distilled water (per IS 1070-1960) must be used when water acts as a reagent in lime testing/preparation to avoid impurities affecting results.

• Water Content Determination (Clause 3.1.4):

  • Dry a weighed sample in an oven at 100 ± 10°C.
  • Loss in mass should be 60-65% of the dry residue mass.
  • This determines the water proportion in lime putty.

• Putty Preparation (Clause 3.1.3.2):

  • Crush quicklime to pass 2.36 mm IS sieve.
  • Slake isothermally for 1 hour (per IS 6932 Part III).
  • Sieve through 850 micron IS sieve.
  • Remove excess water by pressing in filter cloth.
  • Adjust putty water content to 60-65% by mass of dry hydrated lime by adding/removing water.

Key Specification Summary

flowchart TD
    A[Quicklime sample] --> B[Crush through 2.36 mm sieve]
    B --> C[Slake isothermally for 1 hour]
    C --> D[Sieve through 850 micron sieve]
    D --> E[Collect putty on filter cloth]
    E --> F[Press to remove excess water]
    F --> G[Adjust water content to 60-65%]

Note: Use distilled water to ensure chemical consistency and avoid contamination during testing/preparation.

IS 6932 Part 7: Preparation of Standard Lime-Sand Mortar (1:3)

Key Specifications & Steps:

• Hydrated Lime Putty Preparation (Clause 3.1.3.1):

  • Take 500 g hydrated lime.
  • Mix with 60-65% water (by mass).
  • Mix for 5 minutes; pass putty twice through IS:1625-1971 mixer.
  • Use immediately.
  • For mortar: mix 350 g putty with 636-656 g standard sand (3× dry hydrate mass).
  • Mix for 10 minutes continuously to form uniform plastic mortar.
  • Discard remaining putty.

• Quicklime Putty Preparation (Clause 3.1.3.2):

  • Crush ~1 kg quicklime to pass 2.36 mm sieve (IS:460-1962).
  • Slake isothermally for 1 hour (IS:6932 Part III).
  • Stir and sieve through 850-micron sieve.
  • Remove excess water by pressing in filter cloth.
  • Adjust water content to 60-65% by mass of dry hydrate.
  • Mix and knock up thoroughly.

• Mortar Mixing (Clause 3.1.6):

  • Mix 350 g putty with 636-656 g standard sand (IS:650-1971).
  • Mix and knock up for 10 minutes continuously.
  • Use immediately for strength tests.

Summary Table:

IS 6932 Part 7: Preparation and Storage of Test Specimens

Key Specifications

• Storage Duration: 28 days undisturbed.
• Environment:
  • Relative Humidity (RH): ≥ 90%
  • Temperature: 27 ± 2°C
• Storage Setup: Filled mould with base and top plates, covered and kept in a suitable container.
• Temperature Monitoring: Record temperature on at least 24 out of 28 days; monitor max/min to detect fluctuations.

Procedure Summary (Clauses 3.2.1.2 & 3.2.2)

• After 28 days, remove specimens carefully from moulds.
• Maintain undisturbed curing conditions to ensure consistent hydration and strength development.

Reference Standards

• Sample preparation per IS 712:1973, Clause 7.2.
• Use standard sand as per IS 650 (Second Revision) for cement testing.
• Lime mortar preparation as per IS 6932 Part 7 (first revision).

Storage Condition Diagram

flowchart LR
    A[Filled Mould + Base Plate] --> B[Covered with Top Plate]
    B --> C[Placed in Container]
    C --> D[Storage: 28 days]
    D --> E[Environment: ≥90% RH, 27 ± 2°C]
    D --> F[Temperature Monitoring (24 days)]

This ensures consistent curing conditions for reliable test results per IS 6932 Part 7.

IS 6932 Part 7: Determination of Compressive Strength of Mortar

Key Specifications:

• Specimens: 12 cubes total; 6 tested at 14 days, 6 tested at 28 days.
• Storage: 7 days in water (Class B limes under moist sand), then tested.
• Loading: Load applied steadily at 15 kg/min on cube faces that contacted mold sides.
• Testing Machine: One platen self-adjusting on a ball, no packing between cube and platens.

Key Formula:

[ \text{Compressive Strength} = \frac{\text{Maximum Load (kg)}}{\text{Cross-sectional Area (cm}^2)} ]

• Result expressed in kg/cm².
• Average strength of 6 specimens = compressive strength.

Table 3.3 (Clause 3.3.3.1) Summary:

Testing Procedure Flow:

flowchart TD
    A[Prepare 12 cube specimens] --> B[Store 7 days in water/moist sand]
    B --> C[Remove 6 specimens at 14 days]
    C --> D[Test compressive strength at 14 days]
    B --> E[Remove remaining 6 specimens at 28 days]
    E --> F[Test compressive strength at 28 days]
    D & F --> G[Calculate average strength]

For detailed testing and calibration, refer to IS 6932 Part 7 and use the specified testing machine setup and loading rate.

Determination of Transverse Strength (IS 6932 Part 7)

Test Setup (Clause 8.0)

• Specimen immersed in water for 30 min before testing.
• Placed symmetrically on two parallel metal rollers:
  • Roller diameter = 4 cm
  • Roller spacing (center to center) = 8 cm
• Load applied via a third roller (4 cm diameter) at midpoint.
• Load applied steadily at 15 kg/min ± 10%.
• No packing between rollers and specimen.

Formula for Modulus of Rupture (Clause 3.2.3.1)

[ t = k \times \frac{P}{b d^2} ]

Where:

• ( t ) = modulus of rupture (kg/cm²)
• ( P ) = total load at failure (kg)
• ( b ) = width of specimen (cm)
• ( d ) = depth/thickness of specimen (cm)
• ( k = 0.768 ) (for units as specified)

Summary Table

flowchart LR
    A[Specimen] -->|Rest on| B[Two parallel rollers (4 cm dia, 8 cm apart)]
    C[Load roller (4 cm dia)] -->|Apply load at midpoint| A
    A -->|Measure load P| D[Calculate modulus of rupture]

This method ensures consistent transverse strength measurement per IS 6932 Part 7.

IS 6932 Part 7: Evaluation and Reporting of Test Results

Key Formulas:

• Compressive Strength (f_c) = Crushing Load (P) / Area (A)
  [ f_c = \frac{P}{A} \quad \text{(kg/cm}^2\text{)} ]

Specifications:

• Test on 6 specimens; the average compressive strength of these is reported as the mortar strength.
• Results are expressed in kg/cm².

Table 3.3 (Clause 3.3.3.1) Summary:

Reporting Guidelines (Clause 3.2.3 & 3.3.3):

• Clearly state the average compressive strength.
• Mention the area over which load was applied.
• Include details of specimen preparation (Clause 3.2.1).
• Report any deviations or anomalies during testing.

flowchart TD
    A[Specimen Preparation] --> B[Apply Crushing Load]
    B --> C[Measure Load & Area]
    C --> D[Calculate Compressive Strength (P/A)]
    D --> E[Repeat for 6 Specimens]
    E --> F[Calculate Average Strength]
    F --> G[Report Results in kg/cm²]

This ensures standardized, reliable evaluation and reporting per IS 6932 Part 7.

IS 6932 Part 7 (1973) — Notable Amendments & Revisions Summary

• Amendment No. 3 (June 1985):

  • Replaced references:
    • IS 1625-1971 → IS 2250-1981 (masonry mortar code)
    • 'cement' → 'sand' in Clause 3.1.3.1
  • Updated footnote to:
    "Code of practice for preparation and use of masonry mortars (first revision)."

• Amendment No. 4 (July 2010):

  • Updated multiple IS references to latest revisions:
    • IS 712: 1964 → IS 712: 1984 (building limes specification)
    • IS 1070: 1960 → IS 1070: 1992 (reagent grade water)
    • IS 650: 1971 → IS 650: 1991 (building lime)
    • IS 460 (Part 1): 1962 → IS 460 (Part 1): 1985 (test sieves)
    • IS 2250: 1971 → IS 2250: 1981 (masonry mortar code)
  • Footnotes updated to reflect latest revisions and specifications.

• General:

  • Rounding off test results per IS 2-1960.
  • Reaffirmed in 2009, ensuring continued relevance.

Key Specification References (Post-Amendments)

Note: These amendments mainly update referenced standards to their latest revisions, ensuring test methods align with current best practices.

flowchart LR