What is the ductility test of bitumen?

The ductility test measures the distance in centimeters that a bitumen sample can be stretched before it breaks. It indicates the adhesive and elastic properties of bitumen.

At what temperature is the ductility test performed?

The ductility test specimen is conditioned and tested at 27°C as per standard requirements.

What equipment is used in the ductility test?

Equipment includes the ductility testing machine, briquette moulds, and a hot knife for trimming the sample.

What is the minimum ductility value of bitumen?

For A35 & S35 grade bitumen, the minimum ductility value is 50 cm at 27°C. For all other grades, it is 75 cm at 27°C.

Why is ductility important in road construction?

Ductility indicates the flexibility and cohesiveness of bitumen. High ductility ensures that the binder can deform without cracking under traffic loads and temperature variations.

Ductility Test of Bitumen – Procedure, Apparatus & Limits (IS Method)

Ductility Test of Bituminous Material – IS Standard Procedure

Table of Contents

1. Objective
2. Apparatus
3. Procedure
4. Results
5. Limits

1. OBJECTIVE

To determine the ductility of bituminous material, which measures the distance a bitumen sample can stretch before breaking.

2. APPARATUS

Ductility testing machine
Briquette moulds
Hot knife

3. PROCEDURE

Melt the bitumen sample to 75–100°C above its softening point until it becomes fully fluid.
Strain the material through a 90-micron sieve, pour into the mould assembly, and place on a brass plate after applying a mixture of glycerine and dextrin to all mould surfaces.
Allow it to stand for 30–40 minutes, then place the mould assembly in a water bath maintained at 27°C for 30 minutes.
Remove mould from water bath and level the surface using a hot knife to cut off excess material.
After trimming, place the specimen back in the water bath at 27°C for 85–95 minutes.
Remove sides of mould and attach the clips to the ductility machine carefully without applying initial strain.
Start the machine, setting pointer to zero, and apply tension at a uniform speed of 50 ± 2.5 mm/min.
Ensure the sample remains immersed in water at a depth of at least 10 mm throughout the test.
Record the distance (in cm) at which the bitumen thread breaks. This is the ductility value.

4. RESULTS

The ductility value is the distance stretched (in centimeters) by the moving end of the briquette specimen at the point where the bitumen thread breaks.