Softening point test

Softening point test

1. Erbil Polytechnic University
Erbil Technical College
Highway Engineering Department

HE203- Asphalt Technology Laboratory

Eng. Ali Hussein
www. Alihussein.rf.gd

Softening Point Test of Bituminous

Materials

2. Introduction

as
‘Softening
Point

Bitumen

Strarfing Point End Point

3. Introduction E

Softening point: is that degree of temperature in which the asphalt will
start to change from solid to liquid state under specific situation. In
other words, Softening point denotes the temperature at which the
bitumen attains a particular degree of softening under the specifications
of test. The test is conducted by using Ring and Ball apparatus. A brass
ring containing test sample of bitumen is suspended in liquid like water
or glycerin at a given temperature. A steel ball is placed upon the
bitumen sample and the liquid medium is heated at a rate of 5 C per
minute. Temperature is noted when the softened bitumen touches the
metal plate which is at a specified distance below. Generally, higher
softening point indicates lower temperature susceptibility and is
preferred in hot climates.

Eng. Ali Hussein Omar

4. Introduction

For different types of works and in different temperature zones,
materials will be chosen according to their penetration grades. The test
is useful to determine the penetrations index which is given as:

20 — PI se log(800) — log(Pen.

10+PI Tsoftening point — Tpenetration

Where:
PI = Penetration index
Pen. = Penetration value

Tsoftening point = Softening point value (C°)
Tpenetration= Penetration test temperature = 25 C°.

Eng. Ali Hussein Omar

5. Significance of the test

1. The softening point test is used to measure and specify the
temperature at which bituminous binders begin to show fluidity.

2. The softening point is also an indicative of the tendency of the
material to flow at elevated temperatures encountered in service.

3. For calculating the penetration index (PI) of the grade asphalt.

Eng. Ali Hussein Omar

6. Apparatus a

1. Softening point test instrument. Ring and ball complex consist of
two rings, two ball guides and two steel balls with diameter of (9.5)
mm, weight is (3.5) gm. for each.

2. Oiled glass.
3. Heater.
4. Cleveland cup, gloves, tongues and thermometer.

Eng. Ali Hussein Omar

8. Precision a

The difference between the two readings is not more than (1) C°.

The distance between the container bottom and the holder frame
should not pass (20) mm.

Select freshly boiled distilled water for softening point between
(30-80) C°, and USP glycerin for softening point (above 80 C° up

to 157 C°). Use ethylene glycol for softening point between 30
C° and 110 C°.

9. Test procedure a

*% Heating asphalt to (75 — 100) C°.
“ Mix the asphalt during the heating continuously for getting a
uniform asphalt.

* Putthe oiled glass on a horizontal layer and fill the two heated
rings with asphalt on it.

2 Cooling the sample in air for (1/2) hr. and cut the access asphalt by
hot sharp knives.

“ Collect the test instruments all together and put it in water of (5)
C° for 15 minutes.

Eng. Ali Hussein Omar

10. Test procedure a

* Putthe two balls on their places on the samples.
“Start heating the water in rate of (5) C° /min.

The asphalt with the two balls will start down ward to touch the
frame base.

“ Write down the two temperatures of the two balls when touch the
base of the frame.

“ The softening point is the average of the two temperature readings.

Eng. Ali Hussein Omar

11. Calculations and Results: a

1. Report the temperature to the nearest 0.5 C° for each ball.
2. The average of the two readings is the softening point.
3. The difference between two tests must not be more than 1 C°.
4. Calculate the penetration index (PI)
0-PI log(800) — log(Pen.)
10+ PI Tsoftening point — Tpenetration
Where:

PI = Penetration index
Pen. = Penetration value
Tsoftening point = Softening point value (C°)

Tyenetration= Penetration test temperature = 25 C°.

Eng. Ali Hussein Omar 1

13. End of Lecture.

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