This document discusses the penetration test used to measure the consistency of asphalt cement. It describes how the test is conducted by loading a standard needle into an asphalt cement sample submerged in a water bath at 77°F for 5 seconds. The penetration reading is recorded in 1/10 mm units and repeated three times to get the average. Higher penetration values indicate softer asphalt grades. Five standard penetration grades - 40-50, 60-70, 85-100, 120-150, 200-300 - are used to classify asphalt cement based on this test.

1. Pavement
Material Lab
Penetration Test
Priyansh Singh
Department of Civil Engineering
Indian Institute of Technology Delhi
catchpriyansh@gmail.com
web.iitd.ac.in/~cez138070
4th February 2015

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Introduction

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ASPHALT TYPES AND USES
Asphalts most commonly used in pavement Construction can
be divided into three types:
Asphalt Concrete .
Emulsified asphalt .
Cutback asphalt.

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Asphalt Cements
Asphalt cement is obtained by the distillation process from
crude petroleum using different refining techniques.
At ambient temperatures asphalt cement is a black, sticky,
semisolid, and a highly viscous material.
The largest use of asphalt cement is in the production of
Hot Mix Asphalt (HMA), which is primarily used in the con-
struction of flexible pavements throughout the world.
The asphalt cement can readily be liquefied by applying
heat for mixing with mineral aggregates to produce HMA.
Being very sticky, it adheres to the aggregate particles and
binds them together.

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Asphalt Consistancy and grade
Several standard grades of asphalt cement, based on con-
sistency, are available commercially.
Three methods have been primarily used to classify asphalt
cements: penetration, viscosity, and performance grade.
The penetration grading of asphalt cement is specified in
ASTM D946 and IS 1203-1978 and is primarily controlled
by the penetration test.
Five standard penetration graded asphalt cements, 40-50,
60-70, 85-100, 120-150, and 200–300, are used for paving
grade asphalt.
the penetration test involves measurement of penetration
with a standard needle into a sample of asphalt cement un-
der standard temperature, time, and load.

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Asphalt Consistancy and grade (cont.)
Obviously, the higher the penetration, the softer the asphalt
cement.
Therefore, a 40-50 pen grade is the hardest grade, and a
200-300 pen grade is the softest grade.

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Consistancy
Consistency describes the degree of fluidity of asphalt ce-
ment at any particular temperature.
Since asphalt cement is a thermoplastic material, its con-
sistency varies with the temperature.
Therefore, it is necessary to measure the consistency of dif-
ferent asphalt cements at the same temperature and shear
loading conditions if comparisons are to be made.
These tests are not normally used much today since the
adoption of the latest testing methodologies.

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Penetration Test
The penetration test is an empirical test used to measure
the consistency of asphalt cement.
Usually penetration is measured at 77◦F (25◦C) which also
approximates average service temperature of the HMA pave-
ments.
At this temperature no simple test method is currently avail-
able to measure the consistency of asphalt cement in terms
of viscosity
Although viscosity is the preferred form of measurement, so
the penetration test is used.

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Penetration Test

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Penetration Test

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Relevant Standards
IS:1203-1978
IS:73-1992
ASTM D946
ASTM D5-13

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Sample Preparation
Figure : Sample for test
A container of asphalt
cement is brought to the
standard test temperature
(usually 77◦F or 25◦C) in a
thermostatically-controlled
water bath.
Dia 55mm/70mm
& Depth 35mm/45mm

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Penetration Needle
The sample is placed under a needle of prescribed dimensions.

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Penetration Test
The needle is loaded with a 100 g weight and is allowed to
penetrate the asphalt cement sample for 5s.
Then the penetration reading noted.
Repeat the penetration test three times on the sample such
each point is 1cm away from previous point.

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Penetration Report
Express the penetration in 10 of mm.
Express the result as the mean of three readings.
Max Difference in three readings allowed:
Penetration Difference in Reading
0 to 49 2
50 to 149 4

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Precision
Repeatability
Reproducibility
Penetration Repeatability Reproducibility
<50 1 4
>50 3 % 8%

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Penetration Result

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References
P. Chakorborty and A. Das. Principles of Transportation
Engineering. PHI Learning (formerly Prentice Hall of
India), 2003.
SK Khanna and CEG Justo. Highway engineering. Nem
Chand & Bros, 1991.

19. Indian Institute of
Technology Delhi
Pavement Material Lab
Priyansh Singh
Webpage: web.iitd.ac.in/~cez138070
Questions ?
Thanks !