Stripping Value of Aggregate – Procedure, Calculation & Result Interpretation
Author: Kishor Kumar · Updated: February 2026 · Read time: ~8 minutes
1. Introduction
The Stripping Value Test evaluates the loss of adhesion between bitumen and aggregate in the presence of water. This test is crucial to ensure durable, water-resistant pavements and minimize premature failures.
- Determines bitumen-aggregate adhesion quality
- Helps select suitable aggregates for hot mix asphalt (HMA)
- Predicts susceptibility of pavement to water damage
2. Engineering Significance
Stripping of bitumen from aggregates can lead to raveling, potholes, and reduced pavement life. Testing the stripping value identifies weak adhesion and ensures selection of aggregates that will provide long-lasting flexible pavements.
3. Importance of Stripping Value Test
- Assess aggregate resistance to bitumen stripping under wet conditions
- Comply with MoRTH and IRC:SP:62 guidelines
- Ensure durable HMA layers in highways
- Plan use of anti-stripping agents if necessary
Higher stripping values indicate weaker adhesion and potential risk of water damage in pavements.
4. Applications in Highway Construction
- Selection of coarse aggregates for wearing course layers
- Checking compatibility of aggregates with bitumen grades
- Approval of aggregates for DBM and HMA layers
Stripping tests are mandatory for NH, SH, PMGSY, and EPC road projects to prevent premature pavement distress.
5. Applicable Standards
- IS:6241 – Determination of Stripping Value of Aggregates
- MoRTH Specifications – Hot Mix Asphalt & DBM layers
- IRC:SP:62 – Guidelines for asphalt mixtures
6. Apparatus Required
- Aggregate sample sieves and trays
- Bitumen of specified penetration grade
- Water bath maintained at 60 ± 1°C
- Glass containers / beakers
- Balance and drying oven
7. Test Procedure
- Heat bitumen to a fluid state and coat aggregate sample thoroughly.
- Immerse coated aggregate in a water bath at 60°C for 24 hours.
- Remove aggregates and dry them at 105°C to constant weight.
- Record initial and final weights to calculate percentage loss of bitumen.
8. Stripping Value Calculation
Formula: Stripping Value (%) = ((W1 – W2) / W1) × 100
| Initial Weight (W1, g) | Final Weight (W2, g) | Stripping Value (%) |
|---|
| 500 | 460 | 8.0 |
| 500 | 450 | 10.0 |
Lower stripping values indicate strong adhesion between bitumen and aggregate, ensuring better water resistance.
9. Result Interpretation
| Stripping Value (%) | Aggregate Adhesion Quality |
|---|
| < 10% | Excellent |
| 10 – 20% | Good |
| 20 – 30% | Fair |
| > 30% | Poor (Not recommended) |
10. Field Engineer Notes
- Ensure uniform bitumen coating for accurate results
- Maintain water bath temperature precisely at 60°C
- Use correct aggregate size fraction as per IS:6241
- Repeat test for multiple samples and calculate average
11. Common Mistakes
- Overheating bitumen leading to oxidation
- Non-uniform coating of aggregates
- Incorrect water bath temperature
- Insufficient drying before weighing
Always verify equipment calibration and strictly follow IS:6241 guidelines.
12. Stripping Value Excel Sheet
⬇ Download Stripping Value Excel Sheet
13. Who Should Read This Guide?
- Highway site engineers
- QA / QC engineers
- Laboratory technicians
- Civil engineering students
- EPC contractors and consultants
14. Conclusion
Stripping Value testing is vital for assessing the water resistance of aggregates in bituminous pavements. Accurate testing ensures long-lasting and durable highway surfaces.
Frequently Asked Questions
What is an acceptable stripping value for aggregates?
Less than 10% is excellent; 10–20% is good; above 30% is poor and not recommended.
Why is the water bath set at 60°C?
This simulates hot climate conditions and accelerates water exposure for evaluating bitumen-aggregate adhesion.
Can this test be applied to all aggregate sizes?
Only the size fraction specified in IS:6241 should be tested to maintain standardization.
Why do stripping results sometimes vary?
Variations occur due to bitumen coating method, aggregate type, water bath temperature, and drying accuracy.
