Method of Test for Determination of Stripping Value of Road Aggregates
1971 Edition

Overview of Stripping Value Test Procedure

Scope (Clause 1.1):

• This method determines the stripping value of road aggregates through static immersion.
• Applicable for aggregates used with penetration grade bitumen, flux bitumen, and road tar in road paving.

Test Highlights (Clause 2.1):

• Retain 200 grams 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 coating and 100°C for tar coating.
• Heat binders to 160°C (bitumen) and 110°C (tar).
• Coat aggregates with 5% binder by weight.
• Cool coated aggregates in a 500 ml beaker at ambient temperature for 2 hours.
• Immerse coated samples in distilled water, cover, and place in a water bath at 40°C for 24 hours.
• Visually assess the degree of binder stripping underwater.

Additional Notes:

• Numerical results are rounded off as per IS 2-1960.
• The test evaluates adhesive bonding critical for pavement longevity.

flowchart LR
    A[Select Aggregates] --> B[Dry and Heat Aggregates]
    B --> C[Heat Binder]
    C --> D[Mix Binder with Aggregates (5% by weight)]
    D --> E[Cool Coated Mix for 2 Hours]
    E --> F[Immerse in Distilled Water]
    F --> G[Water Bath at 40°C for 24 Hours]
    G --> H[Visual Stripping Assessment]

This approach enables evaluation of aggregate suitability regarding binder adhesion and stripping resistance.

Aggregate Sample Preparation as per IS 6241:1971

Essential Requirements (Clause 2.1):

• Sample Size & Sieve Fraction:

  • Use 200 g of aggregates retained on 12.5 mm IS sieve from material passing 20 mm sieve.

• Cleaning and Heating:

  • Thoroughly dry and clean the aggregates.
  • Heat to 150°C for bitumen coating or 100°C for tar coating.

• Binder Heating:

  • Heat bitumen to 160°C and tar to 110°C before mixing.
  • Mix aggregates with 5% binder by weight in a small vessel.

• Post-Coating Handling:

  • Transfer coated aggregates into a 500 ml beaker.
  • Allow to cool at room temperature for approximately 2 hours.

• Water Bath Conditioning:

  • Add distilled water to immerse coated aggregates fully.
  • Cover the beaker and place in a water bath at 40°C with water level at least half the height of the beaker.
  • Maintain for 24 hours.

• Stripping Estimation:

  • After immersion, cool to room temperature and estimate stripping visually under water.

Rounding Off:

• Follow rounding conventions of IS 2-1960 for final results.

flowchart TD
    A[Sample Aggregates] --> B[Dry and Clean]
    B --> C[Heat Aggregates (150°C / 100°C)]
    C --> D[Heat Binder (160°C / 110°C)]
    D --> E[Mix Aggregates with Binder (5%)]
    E --> F[Transfer to Beaker and Cool]
    F --> G[Immerse in Distilled Water]
    G --> H[Water Bath at 40°C for 24 hrs]
    H --> I[Visual Stripping Assessment]

Step-by-Step Test Method for Stripping Value Determination (IS 6241:1971)

Procedure Outline:

• Sample Preparation:

  • Select 200 g aggregates passing 20 mm sieve but retained on 12.5 mm IS sieve.
  • Clean and dry aggregates.
  • Heat aggregates to 150°C for bitumen and 100°C for tar applications.
  • Heat bitumen to 160°C and tar to 110°C.
  • Combine aggregates with 5% binder by weight, ensuring uniform coating.

• Cooling and Immersion:

  • Place coated aggregates in a 500 ml beaker.
  • Cool at ambient temperature for around 2 hours.
  • Cover beaker, immerse aggregates in distilled water, and maintain water bath at 40°C for 24 hours.
  • Water level should be no less than half the beaker’s height.

• Visual Inspection:

  • After immersion, cool beaker to room temperature.
  • Observe and estimate the degree of stripping visually while aggregates remain submerged.

Important Notes:

• Maintain precise temperatures throughout heating steps.
• Binder proportion is critical at 5% by weight.
• Stripping value determined through visual estimation of binder loss.

flowchart TD
    A[Sample Aggregates] --> B[Heat Aggregates]
    B --> C[Heat Binder]
    C --> D[Mix Aggregates and Binder]
    D --> E[Cool Coated Aggregates for 2 Hours]
    E --> F[Immerse in Distilled Water]
    F --> G[Water Bath at 40°C for 24 Hours]
    G --> H[Visual Stripping Evaluation]

Calculation and Expression Guidelines for Stripping Value (IS 6241)

• Definition (Clause 3.1): [

  \text{Stripping Value (%) } = \left( \frac{\text{Area of aggregate surface uncovered by binder}}{\text{Total aggregate surface area}} \right) \times 100

  ]

• Assessment Procedure:

  • Visually determine the uncovered aggregate surface area post static immersion in the bituminous binder.
  • Applicable binders include penetration grade bitumen, flux bitumen, and road tar.

• Reporting (Clause 4.1):

  • Conduct three separate test runs.
  • Calculate the average stripping value and round it to the nearest integer.

This metric reflects the bonding quality between aggregates and bituminous binder, where lower values signify stronger adhesion and enhanced pavement durability.

Standards for Reporting Stripping Value Results (IS 6241)

Summary of Test Parameters:

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

Testing Procedure Recap:

• Use 200 g of aggregates retained on 12.5 mm sieve and passing 20 mm sieve.
• Mix with 5% binder by weight (bitumen heated to 160°C or tar to 110°C).
• Heat aggregates to 150°C (bitumen) or 100°C (tar).
• Cool coated aggregates in a 500 ml beaker at room temperature for 2 hours.
• Immerse in distilled water and maintain at 40°C in a water bath for 24 hours.
• Visually estimate stripping while submerged.

Reporting Instructions:

• Perform three independent tests.
• Report the mean stripping value rounded to the nearest whole number as per IS 2-1960.

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

Precision and Accuracy Aspects of IS 6241 Stripping Value Test

• Purpose: To determine adhesion between road aggregates and bituminous binders through stripping value.
• Sample Specification: 200 g aggregates retained on 12.5 mm sieve, passing 20 mm sieve.
• Binder Content: 5% by weight, heated to 160°C (bitumen) or 110°C (tar).
• Aggregate Heating: 150°C for bitumen and 100°C for tar.
• Procedure:
  • Mix heated aggregates with binder.
  • Cool coated aggregates in 500 ml beaker at ambient temperature for ~2 hours.
  • Immerse in distilled water; maintain water bath at 40°C for 24 hours.
  • Cool to room temperature and visually assess stripping while submerged.
• Precision: Average of three test results reported, rounded per IS 2-1960.

Stripping Value Formula:

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

(Visual observation is the primary method; weight measurements may supplement.)

flowchart TD
    A[Aggregate Sample] --> B[Heat Aggregates (150°C/100°C)]
    B --> C[Heat Binder (160°C/110°C)]
    C --> D[Mix Aggregates and Binder (5%)]
    D --> E[Cool for 2 Hours]
    E --> F[Immerse in Distilled Water]
    F --> G[Water Bath at 40°C for 24 Hours]
    G --> H[Cool and Visual Stripping Evaluation]

Importance and Application of Stripping Value Test Results (IS 6241:1971)

• Objective: To evaluate the resistance of aggregates to binder stripping under moisture conditions, ensuring durable road pavements.

• Test Summary:

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

• Interpretation:

  • Lower stripping values indicate improved adhesion and aggregate suitability for bituminous mixtures.

• Rounding:
  • Follow IS 2-1960 for rounding numerical results.

flowchart TD
    A[Start: Aggregate Sample] --> B[Heat Aggregates]
    B --> C[Heat Binder]
    C --> D[Mix Aggregates and Binder]
    D --> E[Cool 2 Hours at Room Temperature]
    E --> F[Immerse in Water at 40°C]
    F --> G[Maintain 24 Hours in Water Bath]
    G --> H[Visual Estimate Stripping Value]
    H --> I[Report per IS 2-1960 Guidelines]

IS 6241: Standard Procedure for Stripping Value Determination of Road Aggregates

Essential Test Parameters and Process

• Retain 200 g of aggregates passing 20 mm sieve and retained on 12.5 mm sieve.
• Clean and dry 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.
• Transfer coated aggregates to a 500 ml beaker.
• Cool at room temperature for 2 hours.
• Immerse coated aggregates in distilled water.
• Maintain water bath at 40°C for 24 hours; water level at least half the beaker height.
• Remove, cool to room temperature, and visually estimate stripping under water.

Notes

• Stripping value indicates the bonding strength between aggregate and binder.
• Visual estimation requires careful and consistent observation.
• This test helps confirm the appropriateness of aggregates for use in bituminous road layers.

flowchart TD
    A[Aggregate Sample] --> B[Dry and 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 Temperature (2 hrs)]
    G --> H[Immerse in Distilled Water]
    H --> I[Water Bath at 40°C for 24 hrs]
    I --> J[Remove and Cool]
    J --> K[Visual Stripping Assessment]

IS 6241:1971 does not include specific appendices but comprehensively details the method for determining the stripping value of road aggregates. Key procedural highlights include:

• Sample retention of 200 g aggregates passing 20 mm sieve and retained on 12.5 mm sieve.
• Heating aggregates to 150°C for bitumen or 100°C for tar.
• Heating binders to 160°C (bitumen) or 110°C (tar).
• Coating aggregates with 5% binder by weight.
• Cooling coated samples in a 500 ml beaker at room temperature for 2 hours.
• Immersion in distilled water, covered, kept in water bath at 40°C for 24 hours.
• Visual estimation of stripping while aggregates remain submerged.

Rounding of numerical results adheres to IS 2-1960.

This test is crucial for confirming aggregate-binder adhesion quality, directly influencing the performance and longevity of bituminous pavement layers.

flowchart TD
    A[Obtain Aggregate Sample] --> B[Heat Aggregates]
    B --> C[Heat Binder]
    C --> D[Mix Aggregates and Binder]
    D --> E[Cool for 2 Hours]
    E --> F[Immerse in Water]
    F --> G[Water Bath at 40°C for 24 Hours]
    G --> H[Cool and Visually Assess Stripping]