Method of Test for Determination of Stripping Value of Road Aggregates

IS 6241 - Scope Summary and Key Specifications

Scope (Clause 1.1):

• Covers the determination of stripping value of road aggregates by the static immersion method.
• Applicable for aggregates used with penetration grade bitumen, flux bitumen, and road tar in road construction.

Key Test Procedure Highlights (Clause 2.1):

• Retain 200 g of aggregates passing 20 mm IS sieve but retained on 12.5 mm IS sieve.
• Dry, clean, and heat aggregates to:
  • 150°C for bitumen mixing
  • 100°C for tar mixing
• Binder heated to:
  • 160°C (bitumen)
  • 110°C (tar)
• Mix aggregates with 5% binder by weight.
• After coating, cool mixture in a 500 ml beaker at room temperature for 2 hours.
• Immerse coated aggregates in distilled water, cover, and keep in a water bath at 40°C for 24 hours.
• Visually estimate stripping while still under water.

Important Notes:

• Rounding of numerical values follows IS 2-1960.
• Test ensures adhesion quality of aggregates with binders, critical for durability of bituminous roads.

flowchart LR
    A[Aggregate Selection] --> B[Dry & Heat Aggregates]
    B --> C[Heat Binder]
    C --> D[Mix 5% Binder with Aggregates]
    D --> E[Cool Mixture 2 hrs]
    E --> F[Immerse in Distilled Water]
    F --> G[Water Bath at 40°C for 24 hrs]
    G --> H[Visual Stripping Value Estimation]

This method helps assess aggregate suitability for bituminous road layers by measuring binder adhesion and resistance to stripping.

IS 6241: Sampling & Sample Preparation for Stripping Value Test

Key Steps & Specifications (Clause 2.1):

• Sample Size & Sieve:

  • Retain 200 g of aggregates on 12.5-mm IS sieve from material passing 20-mm IS sieve.

• Drying & Heating:

  • Dry and clean aggregates.
  • Heat aggregates to:
    • 150°C (for bitumen coating)
    • 100°C (for tar coating)

• Binder Preparation:

  • Heat binder to:
    • 160°C (bitumen)
    • 110°C (tar)
  • Mix aggregates with 5% binder by weight in a small casserole.

• Coating & Cooling:

  • After coating, transfer mixture to a 500 ml beaker.
  • Cool at room temperature for about 2 hours.

• Water Bath Conditioning:

  • Add distilled water to immerse coated aggregates.
  • Cover beaker, place in water bath at 40°C, water level at least half the beaker height.
  • Keep for 24 hours.

• Visual Estimation:

  • After 24 hours, cool beaker to room temperature.
  • Estimate extent of stripping visually under water.

Rounding Off Numerical Values

Follow IS 2-1960 for rounding off final values.

Summary Table:

flowchart TD
    A[Aggregate Sampling] --> B[Dry & Clean]
    B --> C[Heat Aggregates (150°C/100°C)]
   

IS 6241 (1971) - Test Procedure for Determination of Stripping Value of Road Aggregates

Key Steps:

• Sample Preparation:

  • Retain 200 g of aggregates passing 20 mm sieve but retained on 12.5 mm IS sieve.
  • Dry and clean aggregates.
  • Heat aggregates to:
    • 150°C for bitumen mixing.
    • 100°C for tar mixing.
  • Heat binder to:
    • 160°C for bitumen.
    • 110°C for tar.
  • Mix aggregates with 5% binder by weight.

• Coating & Cooling:

  • After coating, transfer mixture to a 500 ml beaker.
  • Cool at room temperature for about 2 hours.

• Immersion & Heating:

  • Add distilled water to immerse aggregates.
  • Cover beaker and place in water-bath at 40°C for 24 hours.
  • Water level in bath should be at least half the height of the beaker.

• Evaluation:

  • Remove beaker, cool to room temperature.
  • Visually estimate extent of stripping while specimen is still underwater.

Important Notes:

• Binder content: 5% by weight of aggregates.
• Temperatures for heating aggregates and binders are critical.
• Stripping value is a qualitative visual estimate of adhesion loss.

Summary Table of Temperatures and Binder Content:

This test evaluates the adhesion between aggregates and bituminous binder to assess aggregate suitability for road construction.

flowchart TD
    A[Sample Aggregates] --> B[Heat Aggregates (150°C or 100°C)]
    B --> C[Heat Binder (160°C or 110°C)]
    C --> D[Mix Aggregates + Binder (5%)]
    D --> E[Transfer to Beaker, Cool 2 hrs]
    E --> F[Add Distilled Water to Immerse]
    F --> G[Water Bath at 40°C for 24 hrs]
    G -->

IS 6241: Calculation and Expression of Stripping Value

• Definition (Clause 3.1):
  [ \text{Stripping Value (%)} = \left(\frac{\text{Uncovered area of aggregates}}{\text{Total aggregate area}}\right) \times 100 ]

• Test Procedure:

  • Visual observation of the uncovered aggregate area after static immersion in bitumen binder.
  • Use penetration grade bitumen, flux bitumen, or road tar as binders (Clause 1.1).

• Reporting (Clause 4.1):

  • Perform 3 tests.
  • Report the mean stripping value rounded to the nearest whole number.

Summary Table for Reporting

This value helps assess the adhesion quality between aggregates and bitumen in road construction. Lower stripping values indicate better adhesion and durability.

IS 6241: Reporting of Results for Stripping Value of Road Aggregates

Key Specifications:

• Stripping Value (%) = (Uncovered aggregate area / Total aggregate area) × 100
  (Clause 3.1)

• Test Procedure Summary:

  • Use 200 g aggregates retained on 12.5 mm IS sieve, passing 20 mm sieve.
  • Mix with 5% binder (bitumen at 160°C or tar at 110°C).
  • Coat aggregates heated at 150°C (bitumen) or 100°C (tar).
  • Cool coated aggregates in 500 ml beaker at room temperature for 2 hours.
  • Immerse in distilled water, keep in water bath at 40°C for 24 hours.
  • Visually estimate stripping while still underwater.

Reporting:

• Perform 3 tests.
• Report mean stripping value of the three results.
• Round off to the nearest whole number as per IS 2-1960 (Clause 4.1).

Summary Table for Reporting

flowchart TD
    A[Prepare Aggregates] --> B[Heat Binder & Aggregates]
    B --> C[Mix Binder with Aggregates]
    C --> D[Cool Mixture for 2 Hours]
    D --> E[Immerse in Water at 40°C for 24h]
    E --> F[Visual Inspection Underwater]
    F --> G[Calculate Stripping Value %]
    G --> H[Report Mean of 3 Tests Rounded Off]

This method ensures consistent and standardized reporting of stripping values critical for assessing aggregate suitability in bituminous roads.

IS 6241: Precision and Accuracy - Key Points

• Test: Determination of Stripping Value of Road Aggregates (adhesion of aggregates with bituminous binders).
• Sample: 200 g aggregates retained on 12.5 mm sieve, passing 20 mm sieve.
• Binder: 5% by weight; heated to 160°C (bitumen) or 110°C (tar).
• Aggregate Heating: 150°C for bitumen mix, 100°C for tar mix.
• Procedure:
  • Mix heated aggregates with binder.
  • Cool coated aggregates in a 500 ml beaker at room temperature (~2 hrs).
  • Immerse in distilled water; keep in water bath at 40°C for 24 hrs.
  • Cool to room temperature; visually estimate stripping under water.
• Precision: Mean of three test results reported as stripping value, rounded to nearest whole number (IS 2-1960 rounding rules).

Formula for Stripping Value (SV):

[ SV = \frac{\text{Weight of coated aggregates after immersion}}{\text{Initial weight of coated aggregates}} \times 100 ]

(Visual estimation is primary; weight measurement may supplement)

Summary Table:

flowchart TD
    A[Aggregate Sample] --> B[Heat Aggregates (150°C/100°C)]
    B --> C[Heat Binder (160°C/110°C)]
    C --> D[Mix Aggregates + Binder (5%)]
    D --> E[Cool Coated Aggregates (2 hrs)]
    E --> F[Immerse in Distilled Water]
    F --> G[Water Bath at 40°C for 24 hrs]
    G --> H[Cool to Room Temp]
    H --> I[Visual Estimation of Stripping

Significance and Use of Test Results (IS 6241:1971)

The Stripping Value Test evaluates the adhesion between aggregates and bituminous binders, crucial for durable road construction.

Key Points:

• Purpose:
  To assess the suitability of aggregates by measuring their resistance to stripping (loss of binder) when immersed in water at elevated temperature.

• Test Procedure Summary:

  • Use 200 g of aggregates retained on 12.5 mm IS sieve, passing 20 mm sieve.
  • Heat aggregates to 150°C (bitumen) or 100°C (tar).
  • Heat binder to 160°C (bitumen) or 110°C (tar).
  • Mix aggregates with 5% binder by weight.
  • Cool coated aggregates in a beaker at room temperature for 2 hours.
  • Immerse in distilled water, keep in water bath at 40°C for 24 hours.
  • Visually estimate stripping under water.

• Interpretation:
  Lower stripping values indicate better adhesion and aggregate suitability for bituminous mixes.

Rounding Off Test Results:

Follow IS 2-1960 rules for numerical rounding.

Summary Table:

flowchart TD
    A[Start: Aggregate Sample] --> B[Heat Aggregates]
    B --> C[Heat Binder]
    C --> D[Mix Aggregates + Binder (5%)]
    D --> E[Cool Mixture 2 hrs at RT]
    E --> F[Immerse in Water (40°C)]
    F --> G[Keep 24 hrs in Water Bath]
    G --> H[Visual Estimate Stripping Value]
    H --> I[Report Results per IS 2-1960]

**

IS 6241: Method of Test for Determination of Stripping Value of Road Aggregates

Key Specifications & Procedure Summary

• Sample Preparation:

  • Retain 200 g of aggregates passing 20 mm sieve and retained on 12.5 mm sieve.
  • Dry and clean aggregates.
  • Heat aggregates to 150°C (bitumen) or 100°C (tar).
  • Heat binder to 160°C (bitumen) or 110°C (tar).
  • Mix aggregates with 5% binder by weight.

• Testing:

  • Transfer coated aggregates to 500 ml beaker.
  • Cool at room temperature (~2 hours).
  • Immerse in distilled water.
  • Keep in water bath at 40°C for 24 hours (water level at least half the beaker height).
  • Remove, cool, and visually estimate stripping while still underwater.

• Rounding Off:

  • Follow IS 2-1960 for rounding numerical values.

Important Notes

• Stripping value indicates adhesion quality between aggregate and binder.
• Visual estimation is subjective; careful observation required.
• The test helps assess suitability of new aggregates for bituminous road construction.

Summary Table

flowchart TD
    A[Aggregate Sample] --> B[Dry & Clean]
    B --> C[Heat Aggregates (150°C/100°C)]
    D[Heat Binder (160°C/110°C)] --> E[Mix Binder with Aggregates (5%)]
    C --> E
    E --> F[Transfer to 500 ml Beaker]
    F --> G[Cool at Room Temp (2 hrs)]
    G --> H[Immerse in Distilled Water]
    H --> I[Water Bath at 40°C for 24 hrs]
    I --> J[Remove & Cool

IS 6241 (1971) does not contain specific appendices but details the method for determining the stripping value of road aggregates. Key points and procedure are:

Key Specifications & Procedure:

• Sample Preparation:

  • Retain 200 g aggregates passing 20 mm sieve but retained on 12.5 mm sieve.
  • Heat aggregates to 150°C (bitumen) or 100°C (tar).
  • Heat binder to 160°C (bitumen) or 110°C (tar).
  • Mix aggregates with 5% binder by weight.

• Testing:

  • Transfer coated aggregates to a 500 ml beaker.
  • Cool at room temperature for 2 hours.
  • Immerse in distilled water and cover.
  • Keep in water bath at 40°C for 24 hours (water level at least half the beaker height).
  • Remove, cool, and visually estimate stripping while still underwater.

Rounding:

• Follow IS 2-1960 rules for rounding off numerical values.

Summary Table:

This test helps assess adhesion quality of aggregates with binders, critical for durable bituminous road surfacing.

flowchart TD
    A[Sample aggregates] --> B[Heat aggregates]
    B --> C[Heat binder]
    C --> D[Mix aggregates & binder]
    D --> E[Cool mixture 2 hrs]
    E --> F[Immerse in water]
    F --> G[Water bath at 40°C for 24 hrs]
    G --> H[Cool & visually estimate stripping]

For detailed test setup and visual rating, refer to the full IS 6241 document.