Methods of physical tests for hydraulic cement, Part 7: Determination of compressive strength of masonry cement

IS 4031 Part 7: Scope - Key Points & Tables

Scope Summary:

• IS 4031 Part 7 specifies methods for testing cement.
• It ensures standardization in cement testing procedures.
• Applies to physical and chemical tests relevant to cement quality.

Key Specifications:

• Standard Weights for Testing (Clause 5.2, Table 1):

• Rounding Off (Clause 0.4):
  Results must be rounded per IS 2:1960, retaining the same number of significant digits as specified.

Notes:

• The scope covers apparatus calibration, sampling, and test procedures.
• BIS holds copyright; reproduction requires permission except for implementation use.

flowchart TD
    A[IS 4031 Part 7 Scope] --> B[Testing Methods]
    B --> C[Physical Tests]
    B --> D[Chemical Tests]
    B --> E[Standard Weights (Table 1)]
    E --> F[Permissible Variations]
    B --> G[Rounding Off Rules (IS 2:1960)]

For detailed test procedures and formulas, refer directly to IS 4031 Part 7 full text.

IS 4031 Part 7: Sampling and Selection of Test Specimens for Masonry Cement

Key Points:

• Sampling Method:
  Samples must be taken per IS 3535-1986 and the relevant cement standard.
  The sample should be representative and thoroughly mixed before testing.

• Test Specimen:
  Compressive strength is tested on 50 mm mortar cubes.

• Weights for Sample Preparation:
  Use standard weights with permissible variation as per Table 1 below:

Summary Diagram:

flowchart TD
    A[Sampling per IS 3535] --> B[Representative Sample]
    B --> C[Thorough Mixing]
    C --> D[Prepare 50 mm Mortar Cubes]
    D --> E[Weigh Components with Standard Weights]
    E --> F[Apply Permissible Weight Variations]
    F --> G[Conduct Compressive Strength Test]

This ensures reliable and standardized compressive strength results for masonry cement.

IS 4031 Part 7: Temperature and Humidity Specifications

• Moulding Room, Dry Materials & Water Temperature:
  Maintain at 27 ± 2°C (Clauses 3.1, 7.1)

• Laboratory Relative Humidity:
  Maintain at 65 ± 5% (Clause 3.1)

• Moist Closet / Moist Room Conditions:
  Temperature: 27 ± 2°C
  Relative Humidity: ≥ 90% (Clause 3.2)

• Water for Mixing:
  Use potable/distilled water at 27 ± 2°C (Clause 7.1)

Summary Table

Notes:

• Maintaining these conditions ensures consistent hydration and curing of cement specimens.
• Temperature and humidity control is critical for reliable strength and setting time tests.

flowchart LR
    A[Start: Cement Sample] --> B[Moulding Room @ 27±2°C]
    B --> C[Mixing with Water @ 27±2°C]
    C --> D[Lab Environment @ 65±5% RH]
    D --> E[Moist Room @ 27±2°C & ≥90% RH]
    E --> F[Specimen Curing & Testing]

Standard Sand as per IS 4031 (Part 7) & IS 650:1966

• Specification: Standard sand must conform to IS 650-1966 (Specification for standard sand for testing cement).
• Mix Proportions (Clause 7.2):

• Permissible Weight Variations (Clause 5.2, Table 1):

• Mould Preparation (Clause 6.1): Interior faces of specimen moulds are lightly coated with mineral oil or light grease to prevent adhesion and ensure easy removal.

Summary:

• Use IS 650-1966 standard sand.
• Mix 420 g cement + 1440 g standard sand for mortar cubes.
• Weigh materials within permissible variation limits.
• Prepare moulds with a thin coating of mineral oil or grease.

flowchart TD
    A[Standard Sand (IS 650-1966)] --> B[Mix with Masonry Cement]
    B --> C[420 g Cement + 1440 g Sand]
    C --> D[Prepare Moulds]
    D --> E[Coat Interior with Mineral Oil/Grease]
    E --> F[Cast Mortar Cubes]

This ensures consistency and reliability in mortar testing per IS 4031 (Part 7).

IS 4031 Part 7 - Apparatus Key Points

1. Standard Weights (Clause 5.2 & Table 1)

Weights used for weighing cement must conform to these permissible variations:

2. Flow Table and Accessories (Clause 5.5)

• Must conform to IS 5512-1983.
• Used for consistency tests of cement.

3. Mixing Conditions (Clause 7.1)

• Use clean appliances for mixing.
• Temperature of water and test room: 27 ± 2°C.
• Use potable or distilled water for preparing test cubes.

This ensures accuracy in cement testing apparatus and conditions as per IS 4031 Part 7.

IS 4031 Part 7: Preparation of Moulds – Key Points

• Mould Coating (Clause 6.1):
  Interior faces of specimen moulds must be thinly coated with mineral oil or light cup grease to prevent sticking.
  Excess oil/grease should be wiped off from interior faces and top/bottom surfaces after assembly.

• Base Plates:
  Moulds are placed on plane, non-absorbent base plates, also thinly coated with mineral oil, petrolatum, or light cup grease.

• Environmental Conditions (Clause 3.1):

  • Temperature: 27 ± 2°C
  • Relative Humidity: 65 ± 5%

• Mixing and Moulding (Clause 7.4):

  • Dry materials and water quantities per IS 4031 specifications.
  • Mechanical mixing recommended for uniformity.
  • Use tamping rod as per IS 10086-1982 (Clause 5.6).

Summary Table for Mould Preparation

flowchart TD
    A[Prepare Mould] --> B[Apply thin mineral oil / grease]
    B --> C[Assemble mould]
    C --> D[Remove excess oil from interior & surfaces]
    D --> E[Place on coated, plane base plate]
    E --> F[Mix mortar mechanically]
    F --> G[Fill mould & tamp as per IS 10086]
    G --> H[Cure under controlled temp & humidity]

This ensures proper specimen preparation for consistent test results.

IS 4031 Part 7: Preparation of Mortar – Key Points

1. Material Proportions (Clause 7.2)

2. Mixing Water (Clause 7.3.1)

• Trial mixes with varying water % to achieve specified flow.
• Use fresh mortar for each trial.

3. Mixing Procedure (Clause 7.3.1)

4. Specimen Mould Preparation (Clause 6.1)

• Interior faces of moulds thinly coated with mineral oil or light cup grease.
• Excess oil removed before assembly.
• Moulds placed on non-absorbent base plates also coated thinly with oil or grease.

Summary Diagram: Mixing Sequence

flowchart TD
    A[Add Water] --> B[Add Masonry Cement, Mix Slow 30s]
    B --> C[Add Sand Slowly 30s, Mix Slow]
    C --> D[Mix Medium Speed 30s]
    D --> E[Rest 1.5 min with scraping

IS 4031 Part 7: Moulding of Specimens - Key Points

1. Mixing & Materials (Clause 7.4)

• Mix each batch separately using dry materials per proportions in 7.2.
• Water quantity as per 7.3.
• Mechanical mixing as described in 7.3.1.

2. Mould Preparation (Clause 6.1)

• Interior faces of moulds thinly coated with mineral oil or light cup grease.
• Remove excess oil/grease after assembly.
• Moulds placed on plane, non-absorbent base plates coated with the same lubricant.

3. Environmental Conditions (Clause 3.1)

• Temperature: 27 ± 2°C
• Relative Humidity: 65 ± 5%

4. Equipment Specifications

• Tamping rod as per IS 10086-1982 (6.1(c))
• Use standard specifications for moulds, planetary mixers, and flow tables as referenced.

Typical Mould Dimensions (IS 4031 Part 7)

Summary Diagram: Moulding Process Flow

flowchart TD
    A[Prepare Dry Materials] --> B[Measure Water]
    B --> C[Mechanical Mixing]
    C --> D[Apply Lubricant to Mould]
    D --> E[Assemble Mould & Remove Excess Oil]
    E --> F[Fill Mould with Mortar]
    F --> G[Tamp Mortar Using Tamping Rod]
    G --> H[Store Specimens at 27±2°C, 65±5% RH]

This ensures consistent specimen quality for cement and concrete testing per IS 4031 Part 7.

Storage and Curing of Specimens as per IS 4031 Part 7

• Immediately after moulding and compaction:

  • Keep specimens in moulds on plane plates in a moist cabinet.
  • Maintain temperature: 27 ± 2°C and RH ≥ 90%.
  • Duration: 48 to 52 hours.
  • Upper surfaces exposed to moist air.

• After 48-52 hours:

  • Remove cubes from moulds.
  • Place in moist cabinet for 5 days, allowing free air circulation around at least 5 faces.

• Post 5-day moist curing:

  • For 7-day strength: test immediately.
  • For 28-day strength: immerse cubes in clean water (non-corrosive tanks) for 21 additional days.

• Testing:

  • 7-day cubes tested immediately after removal from moist cabinet.
  • 28-day cubes tested immediately after removal from water.
  • If multiple specimens removed simultaneously:
    • 7-day cubes: cover with damp cloth.
    • 28-day cubes: keep immersed in water at 29 ± 2°C until testing.

Summary Table:

Important Notes:

• Moulds must be thinly coated with mineral oil or light grease before use (Clause 6.1).
• Start moulding specimens within 2 min 15 s after mixing (Clause 8.1).
• For multiple specimens, maintain proper moisture until testing (Clause 10.2).

flowchart TD
    A[Mixing & Moulding] --> B[In Moulds in Moist Cabinet]
    B -->|48

IS 4031 Part 7: Testing of Cement Specimens – Key Points

Specimen Preparation & Moulding

• Mix materials per Clause 7.4: dry materials and water as per proportions in 7.2 and 7.3.
• Mechanical mixing is mandatory (7.3.1).
• Mould cubes immediately after mixing (Clause 8).

Storage Before Testing

• 7-day cubes: store in moist cabinet, test immediately after removal.
• Other ages: store in water at 29 ± 2°C until testing.
• If multiple cubes removed simultaneously, keep them:
  • Covered with damp cloth (7-day cubes).
  • Immersed in water at 29 ± 2°C (others).

Testing Procedure (Clause 10.2.1)

• Test cubes on their sides without packing between cube and steel platens.
• One platen is self-adjusting.
• For expected max load > 13,500 N:
  • Apply initial load up to half max load.
• For expected max load < 13,500 N:
  • No initial load.
• Load rate: reach failure in 20 to 80 seconds continuously.
• No adjustment during rapid yielding before failure.

Calculation of Compressive Strength

[ f_c = \frac{P}{A} ]

• (f_c): compressive strength (N/mm²)
• (P): maximum load at failure (N)
• (A): cross-sectional area of cube face (mm²)

Summary Table: Testing Conditions

flowchart TD
    A[Mixing & Moulding] --> B[Storage]
    B --> C{Test Age}
    C -->|7-day| D[Moist Cabinet → Test Immediately]
    C -->|Others| E[Water Storage @ 29 ± 2°C]
    D & E --> F[Testing Setup]

IS 4031 Part 7 - Key Formulas & Specifications for Calculation (Clause 11.1)

This part deals with the determination of compressive strength of cement cubes.

Key Points for Calculation:

• Compressive Strength (f_c) is calculated as:

  [ f_c = \frac{P}{A} ]

  where:

  • (P) = Maximum load applied on the cube (N)
  • (A) = Cross-sectional area of the cube face (mm²)

• Cube Size: Standard cube size is 70.6 mm × 70.6 mm × 70.6 mm, so:

  [ A = (70.6 , \text{mm})^2 = 4984.36 , \text{mm}^2 ]

• Load Application: As per Clause 10.2.1, apply load continuously at a rate such that failure occurs between 20 to 80 seconds.

• Rounding Off: Final compressive strength values should be rounded as per IS 2:1960—matching significant figures of specified values.

Permissible Variation on Weights (Table 1):

Summary Diagram:

flowchart TD
    A[Prepare Cement Cube] --> B[Place in Testing Machine]
    B --> C[Apply Load at Controlled Rate]
    C --> D[Measure Maximum Load (P)]
    D --> E[Calculate Compressive Strength f_c = P / A]
    E --> F[Round off as per IS 2:1960]

Note: Use calibrated weights with permissible variations as per Table