Penetration test on bitumen by penetrometer

PENETRATION TEST ON BITUMEN:

Objective:

To determine the consistency of Bitumen.

Theory:

Penetration value is a measurement of hardness or consistency of bituminous material. It is the vertical distance traversed or penetrated by the point of a standard needle in to the bituminous material under specific conditions of load, time, and temperature. This distance is measured in one tenth of a millimeter. This test is used for evaluating consistency of bitumen. It is not regarded as suitable for use in connection with the testing of road tar because of the high surface tension exhibited by these materials and the fact that they contain relatively large amount of free carbon.

APPARATUS USE

•  Container A flat bottomed cylindrical metallic dish 55 mm in diameter and 35 mm in depth is required. If the penetration is of the order of 225 or more deeper dish of 70 mm diameter and 45 mm depth is required.

•  Needle: A straight, highly polished, cylindrical hard steel rod, as per standard dimensions

•  Water bath: A water bath maintained at 25.0±0.1°C containing not less than 10 litres of water, the sample being immersed to a depth not less than 100 mm from the top and supported on a perforated shelf not less than 50 mm from the bottom of the bath

•  Transfer dish or tray: It should provide support to the container and should not rock the container. It should be of such capacity as to completely immerse the container during the test.

•  Penetration apparatus: It should be such that it will allow the needle to penetrate without much friction and is accurately calibrated to give results in one tenth of a millimeter

• Thermometer range 0-44 degree C and readable  up to 0.2 degree C.

• Time measuring device.

PROCEDURE 

• Preparation of test specimen: Soften the material to a pouring consistency at a temperature not more than 60°C for tars and 90°C for bitumen's above the approximate softening point and stir it thoroughly until it is homogeneous and is free from air bubbles and water. Pour the melt into the container to a depth at least 10 um in excess of the expected penetration_ Protect the sample from dust and allow it to cool in an atmosphere at a temperature between 15 to 30°C for one hour. Then place it along with the transfer dish in the water bath at 25±0.1°C, unless otherwise stated.

•  Fill the transfer dish with water from the water bath to depth sufficient to cover the container completely, place the sample in it and put it upon the stand of the penetration apparatus.

•  Clean the needle with benzene, dry it and load with the weight. The total moving load required is 100±0.25gms, including the weight of the needle, carrier and super-imposed weights.

• Adjust the needle to make contact with the surface of the sample. This may be done by placing the needle point in contact with its image reflected by the surface of the bituminous material

•  Make the pointer of the dial to read zero or note the initial dial reading

•  Release the needle for exactly five seconds

•  Adjust the penetration machine to measure the distance penetrated.

•  Make at least 3 readings at points on the surface of the sample not less than 10 ram apart and not less than 10 mm from the side of the dish. After each test return the sample and transfer dish to the water bath and wash the needle clean with benzene and dry it . In case of material of penetration greater than 225, three determinations on each of the two identical test specimens using a separate needle for each determination should be made, leaving the needle in the sample on completion of each determinations to avoid disturbance of the specimen.

RESULT

Penetration value of given sample is = After collection all above data you can easily get the penetration value of bitumen.