Method of test for determining aggregate impact value of soft coarse aggregates

IS 5640: Scope Key Points

• Scope: The standard is formulated with inputs from Road Research Monograph No. 5 by Central Road Research Institute, New Delhi. It covers apparatus and procedures related to aggregate impact value testing.

Apparatus Specifications

Reporting (Clause 6.1)

• Report the mean of two test results as the Aggregate Impact Value (wet).

Summary

• The standard defines apparatus dimensions for consistent testing.
• Emphasizes rigidity and precision in measuring tools.
• Uses mean values for reporting impact resistance of aggregates.

flowchart LR
    A[Aggregate Sample] --> B[Cylindrical Metal Measure (75x50mm)]
    B --> C[Impact Testing in Steel Cup (102x50mm, ≥6.3mm thick)]
    C --> D[Record Two Results]
    D --> E[Calculate Mean]
    E --> F[Report Aggregate Impact Value (Wet)]

This ensures uniformity and reliability in testing aggregate toughness per IS 5640.

IS 5640 - Apparatus Specifications Summary

1. Cylindrical Metal Measure (Clause 2.3)

• Material: Metal, rigid to withstand rough use.
• Tare Accuracy: Nearest gram.
• Internal Dimensions:
  • Diameter = 75 mm
  • Depth = 50 mm

2. Cylindrical Steel Cup (Clause 6.3)

• Material: Steel, case-hardened inner surface.
• Thickness: Minimum 6.3 mm
• Internal Dimensions:
  • Diameter = 102 mm
  • Depth = 50 mm
• Feature: Can be rigidly fastened at the base center and easily removed for emptying.

3. Impact Testing Machine (Clause 2.1)

• Total Weight: 45 to 60 kg.
• Base Weight: 22 to 30 kg.
• Base Surface: Plane lower surface ≥ 30 cm diameter.
• Support: Mounted on a level concrete/stone block ≥ 45 cm thick, fixed to prevent rocking.

Visual Summary of Apparatus Dimensions:

graph TD
  A[Cylindrical Metal Measure] -->|Diameter 75 mm| D1[75 mm]
  A -->|Depth 50 mm| D2[50 mm]

  B[Cylindrical Steel Cup] -->|Diameter 102 mm| D3[102 mm]
  B -->|Depth 50 mm| D4[50 mm]
  B -->|Thickness ≥ 6.3 mm| T1[6.3 mm]

  C[Impact Testing Machine] -->|Weight 45-60 kg| W1[45-60 kg]
  C -->|Base Weight 22-30 kg| W2[22-30 kg]
  C -->|Base Diameter ≥ 30 cm| D5[≥ 30 cm]
  C -->|Support Block ≥ 45 cm thick| S1[≥ 45 cm]

This concise summary covers key apparatus dimensions and specifications per IS 5640.

IS 5640: Preparation of Test Sample - Key Points

1. Test Sample Preparation (Clause 3.1)

• Aggregate size: Passes 12.5 mm IS Sieve, retained on 10 mm IS Sieve.
• Drying: Oven dry at 105–110°C for 4 hours or until constant weight.
• Cooling: Cool before testing.

2. Test Sample Weight (Clause 13.5)

• Typical Weight: 13.5 to 14.0 kg.

3. Apparatus Specifications (Clause 6.3)

• Cylindrical Steel Cup:
  • Internal diameter: 102 mm
  • Depth: 50 mm
  • Thickness: ≥ 6.3 mm
  • Inner surface: Case-hardened
  • Must be rigidly fastened and easily removable.

Summary Table: Steel Cup Dimensions

Notes:

• The case-hardened inner surface improves durability and repeatability.
• Sample preparation ensures uniformity and reproducibility of mechanical tests on aggregates.

flowchart TD
    A[Aggregate Sample] --> B[Pass 12.5 mm sieve]
    B --> C[Retain on 10 mm sieve]
    C --> D[Dry at 105-110°C for 4 hrs]
    D --> E[Cool sample]
    E --> F[Fill case-hardened steel cup]
    F --> G[Conduct mechanical test]

This ensures compliance with IS 5640 for reliable aggregate testing.

IS 5640: Test Procedure Key Points

Apparatus (Clause 6.3)

• Cylindrical steel cup:

  • Diameter: 102 mm
  • Depth: 50 mm
  • Thickness: ≥ 6.3 mm
  • Inner surface: Case-hardened
  • Rigidly fastened at center base, removable for emptying

• Impact Testing Machine (Fig. 1)

  • TUP weight: 13.5 - 14.0 kg
  • Case-hardened surface contact

Test Sample Preparation (Clause 3)

• Follow specified mechanical properties methods for aggregates (Part IV)
• Ensure sample fits apparatus dimensions

Reporting Results (Clause 0.4)

• Round off final values as per IS 2-1960 rules

Summary Table: Apparatus Dimensions

Rounding Off (IS 2-1960)

• Round final numerical values according to IS 2-1960 standard rounding rules.

flowchart TD
    A[Test Sample Preparation] --> B[Place in Steel Cup]
    B --> C[Impact Testing Machine Setup]
    C --> D[Perform Impact Test]
    D --> E[Record Observed Values]
    E --> F[Round off per IS 2-1960]
    F --> G[Report Test Results]

This concise overview covers essential apparatus specs, sample prep, and reporting per IS 5640.

IS 5640 Key Specifications & Formulas for Calculations

• Apparatus Dimensions:

• Rounding Off Results:
  • Follow IS 2-1960 for rounding off final values (observed or calculated).

Additional Calculation Notes (Based on Engineering Practice)

• Volume of Cylinder (for capacity checks):

[ V = \pi \times \left(\frac{d}{2}\right)^2 \times h ]

Where:
( d ) = diameter (mm)
( h ) = depth (mm)
( V ) = volume (mm³ or converted to ml/cm³)

• Example: Volume of Measure (75 mm dia, 50 mm depth)

[ V = \pi \times (37.5)^2 \times 50 \approx 220,893 \text{ mm}^3 = 220.9 \text{ ml} ]

flowchart LR
    A[Start: Select Apparatus] --> B{Measure or Cup?}
    B -->|Measure| C[Use 75 mm dia, 50 mm depth]
    B -->|Cup| D[Use 102 mm dia, 50 mm depth, ≥6.3 mm thick]
    C --> E[Calculate Volume]
    D --> E
    E --> F[Perform Test]
    F --> G[Round off results per IS 2-1960]
    G --> H[Report Results]

This concise summary integrates IS 5640 apparatus specs and calculation essentials for test preparation and reporting.

IS 5640: Reporting of Results - Key Points

• Aggregate Impact Value (AIV) (Wet) is reported as the mean of two test results (Clause 6.1).

• Formula for Aggregate Impact Value (AIV):

  [ \text{AIV} = \frac{C}{A} \times 100 ]

  where:

  • (C) = Weight of fines formed (in grams)
  • (A) = Weight of oven-dried sample (in grams)

• Rounding off of final values must comply with IS 2:1960 (Rules for rounding off numerical values).

Summary Table for Reporting

Reporting Steps

1. Perform two tests on the aggregate sample.
2. Calculate AIV for each test using the formula.
3. Report the mean of the two AIV results.
4. Round off as per IS 2:1960.

flowchart TD
    A[Start: Test Aggregate Sample] --> B[Measure weight of fines (C)]
    B --> C[Measure oven-dried sample weight (A)]
    C --> D[Calculate AIV = (C/A) * 100]
    D --> E{Two tests completed?}
    E -- No --> A
    E -- Yes --> F[Calculate mean of two AIV values]
    F --> G[Round off as per IS 2:1960]
    G --> H[Report Aggregate Impact Value (Wet)]

This ensures consistent, standardized reporting of aggregate impact values as per IS 5640.

IS 5640: Notes on Application and Modifications - Key Points

1. Apparatus Specifications (Clause 6.3):

   • Cylindrical steel cup:
     • Internal Diameter = 102 mm
     • Depth = 50 mm
     • Thickness ≥ 6.3 mm
     • Inner surface case-hardened
     • Rigidly fastened at base center, removable for emptying

2. Reporting Results (Clause 6.1):

   • Aggregate Impact Value (wet) = Mean of two test results

3. General Notes:

   • Standard is based on Road Research Monograph No. 5 by Central Road Research Institute.
   • Apparatus and methods align with IS codes for mechanical properties of aggregates.
   • Numerical values should be rounded off as per IS rules.

Summary Table: Apparatus Dimensions

Formula for Aggregate Impact Value (AIV):

[ \text{AIV} = \frac{\text{Mean weight of fines passing 2.36 mm sieve}}{\text{Total weight of sample}} \times 100 ]

flowchart LR
    A[Start Test] --> B[Prepare Sample]
    B --> C[Place in Cylindrical Steel Cup]
    C --> D[Impact Test]
    D --> E[Weigh Fines Passing 2.36 mm Sieve]
    E --> F[Calculate AIV]
    F --> G[Report Mean of Two Results]
    G --> H[End]

For detailed testing procedure and apparatus setup, refer to Clause 2.0 and Clause 6.3 of IS 5640.