penetration test

Pavement

Material Lab

Penetration TestPriyansh SinghDepartment of Civil EngineeringIndian Institute of Technology Delhi@ [email protected] web.iitd.ac.in/~cez138070

4th February 2015

Pavement Material Lab

Penetration Test4th February 2015

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Introduction



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ASPHALT TYPES AND USES

Asphalts most commonly used in pavement Construction canbe divided into three types:

I Asphalt Concrete .I Emulsified asphalt .I Cutback asphalt.



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Asphalt Cements

I Asphalt cement is obtained by the distillation process fromcrude petroleum using different refining techniques.

I At ambient temperatures asphalt cement is a black, sticky,semisolid, and a highly viscous material.

I The largest use of asphalt cement is in the production ofHot Mix Asphalt (HMA), which is primarily used in the con-struction of flexible pavements throughout the world.

I The asphalt cement can readily be liquefied by applyingheat for mixing with mineral aggregates to produce HMA.

I Being very sticky, it adheres to the aggregate particles andbinds them together.



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Asphalt Consistancy and grade

I Several standard grades of asphalt cement, based on con-sistency, are available commercially.

I Three methods have been primarily used to classify asphaltcements: penetration, viscosity, and performance grade.

I The penetration grading of asphalt cement is specified inASTM D946 and IS 1203-1978 and is primarily controlledby the penetration test.

I Five standard penetration graded asphalt cements, 40-50,60-70, 85-100, 120-150, and 200–300, are used for pavinggrade asphalt.

I the penetration test involves measurement of penetrationwith 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.)

I Obviously, the higher the penetration, the softer the asphaltcement.

I Therefore, a 40-50 pen grade is the hardest grade, and a200-300 pen grade is the softest grade.



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Consistancy

I Consistency describes the degree of fluidity of asphalt ce-ment at any particular temperature.

I Since asphalt cement is a thermoplastic material, its con-sistency varies with the temperature.

I Therefore, it is necessary to measure the consistency of dif-ferent asphalt cements at the same temperature and shearloading conditions if comparisons are to be made.

I These tests are not normally used much today since theadoption of the latest testing methodologies.



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Penetration Test

I The penetration test is an empirical test used to measurethe consistency of asphalt cement.

I Usually penetration is measured at 77◦F (25◦C) which alsoapproximates average service temperature of the HMA pave-ments.

I At this temperature no simple test method is currently avail-able to measure the consistency of asphalt cement in termsof viscosity

I Although viscosity is the preferred form of measurement, sothe penetration test is used.



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Penetration Test



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Penetration Test



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Relevant Standards

I IS:1203-1978I IS:73-1992I ASTM D946I ASTM D5-13



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Sample Preparation

Figure : Sample for test

A container of asphaltcement is brought to thestandard test temperature(usually 77◦F or 25◦C) in athermostatically-controlledwater 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

I The needle is loaded with a 100 g weight and is allowed topenetrate the asphalt cement sample for 5s.

I Then the penetration reading noted.I Repeat the penetration test three times on the sample such

each point is 1cm away from previous point.



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Penetration Report

I Express the penetration in 10 of mm.I Express the result as the mean of three readings.I Max Difference in three readings allowed:

Penetration Difference in Reading0 to 49 250 to 149 4



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Precision

I RepeatabilityI 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 TransportationEngineering. PHI Learning (formerly Prentice Hall ofIndia), 2003.

SK Khanna and CEG Justo. Highway engineering. NemChand & Bros, 1991.

Indian Institute of Technology Delhi


Priyansh SinghWebpage: web.iitd.ac.in/~cez138070

Questions ?

Thanks !