TRIBHUWAN UNIVERSITY

KHWOPA COLLEGE OF ENGINEERING

(Undertaking Of Bhaktapur Municipality)

Libali-8, Bhaktapur

A Report on: Transportation Engineering –I

Practical no: 01

Title: Determination of Penetration value of Bitumen

Submitted by: Submitted to:

Name:Unique Bakhrel Department of Civil Engineering

Roll no: KCE074BCE093 Khwopa College of Engineering

Group: D2 Tribhuwan University

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 Date of submission: 2077/10/29

Determination of penetration value of Bitumen

OBJECTIVE:

1. To find the grade of bitumen.

2. To find the penetration value of bitumen.
3. To determine the consistency of bitumen.

APPARATUS REQUIRED:

I. Sample container
II. Penetrometer
III. Penetration needle
IV. Water bath and Stopwatch
V. Thermometer
VI. Transfer tray

MATERIALS REQUIRED

1. Bitumen

THEORY:

Penetration is a measurement of hardness or consistency of bituminous material. Penetration of a

bituminous material is the distance in tenths of millimeter that standard needles will penetrate
vertically into a sample understand conditions of temperature, load and time. It is the vertical
distance traversed or penetrated by the point of a standard needle under specific condition, load,
time and temperature. The distance is measured in one tenth of a millimeter. This test is used for
evaluating consistency of bituminous materials.
Penetration test determines the consistency of the bitumen for the purpose of grading them, by
measuring the depth to which a standard needle will penetrate vertically under specified condition
of standard load, duration and temperature. Thus , the penetration test is the measurement of the
penetration(in unit of one-tenth of mm) of a standard needle in a bitumen sample maintained at
25oC for a period of one hour during 5 seconds release of the total weight of 100gm.The softer
the bitumen, the greater will be the penetration. The bitumen grade is specified in terms of
penetration value. 80-100 or 80/100 grade bitumen means that the penetration value of the
bitumen is in the range 80 to 100 at standard test condition. The penetration values of various
types of bitumen used in pavement are ranged between 20 to 225. 30/40, 60/70 and 80/100 grade

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bitumen are more commonly used, depending on construction type and climatic condition. In hot
climates, lower penetration grade bitumen like 30/40 bitumen is preferred.

PROCEDURE:

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Soften the bitumen to pouring consistency, stir well and pour into test containers. The depth of
bitumen was kept at 15mm more than the expected penetration in container.

The sample container was placed in water bath at a temperature of 25 °C for one hour.

After one hour, the sample was taken out from the water bath and brought in contact the needle with
surface of bitumen sample.

The reading of dial gauge were set at zero when the needle was in contact with the surface of sample.

The needle was released and was allowed to penetrate for 5 seconds and the final reading was noted.

Three measurements were taken and the mean value of these three tests was reported as a penetration
value.

OBSERVATION AND CALCULATION

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 S.N Penetrometer dial reading Penetration value
Initial Final (in one tenth mm)
1 0 112 112
2 0 110 110
3 0 100 100
4 0 76 76
5 0 69 69
6 0 64 64

Penetration value= (112+110+100+76+69+64)/6=88.5

RESULT:

Penetration value of bitumen = 88.5 = 8.85mm

CONCLUSION AND DISCUSSION:

Hence, the consistency of bituminous material was determined using the penetration test.

The penetration values for each experiment should be close to each other. But in this experiment
the values have certain discrepancy. The discrepancy in the penetration values might be because
of certain errors while performing the experiments like experimental errors, human errors. The
difference in the penetration values has occurred mainly due to the cooling of the bitumen test
specimen during the time of testing.

This experiment is temperature sensitive so the slight change in temperature could also have
affected the experiment. We clearly observed that as the time of test bitumen outside the water
bath has increased its temperature decreased and the penetration value also decreased. Similarly,
the result may have been affected by other factors as well such as test temperature, duration of
releasing needle, pouring temperature and cleaning of needle after each test to maintain
consistency in penetration value. In warmer regions lower penetration grades are preferred to
avoid softening whereas higher penetration grades like 180/200 are used in colder regions so that
excessive brittleness does not occur. So the given type of bitumen used in this test can be used in
regions with moderate climate. Hence for accurate readings temperature sensitive is preferred.

PRECAUTIONS:

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1. The appartus must not be subjected to vibrations.
2. Distilled water should be used as heating medium.
3. Temperature of bitumen should be between (25-29) °C
4. The needle of the penetrometer should be cleaned everytime.