Penetration Grade Bitumen:
Penetration Grade Bitumen, is classified by influence trait. This grading’s basic assumption is that less viscous asphalt, deeper the needle will penetrate. Bitumen which is made during oxidation process of vacuum bottom. Bitumen production feed-stock that derives from distillation tower residue in vacuum oil refineries. At bitumen production unit in a manner that its penetration point.
Penetration Grade Bitumen is commonly used in road surfacing, and some industrial applications. Additional processing yields other grades of bitumen products and their application.
it is black semi solid heavy hydrocarbon which is the last product of extract tower which by cool down of ambient temperature will convert to solid. With increase of temperature the bitumen will become semi solid and then liquid. Main content of bitumen us hydrocarbon with high molecular weight contenting oil, resin and asphalten.
Influence measurement in bitumen:
This grading helps to assign its suitability in different climatic state and construction types. Furthermore for paving and penetration macadam, IRC offers bitumen grades 30/40, 60/70, 80/100.
In warmer regions, lower penetration grades are preferred to avoid softening. In addition higher penetration grades like 180/200 used in colder regions to prevent occurrence of excessive fragility. High penetration grade apply in spray usages.
Penetration Grad Bitumen Grading methodes are ASTM D946-09 and EN 12591-2009, including:
ASTM D946-09 Grades:
EN 12591-2009 Grades:
- Consistency of bituminous material
- Suitability of bitumen for use under different climatic conditions and various types of construction
Penetration value is vertical distance traversed. It penetrated by standard needle point into bituminous material under specific conditions of load, time and temperature. This distance measured also in one tenths of a mm.
In addition, this test used for evaluating consistency of bitumen. It`s not regarded as suitable for use in connection with road tar testing. Because of high surface tension exhibited by these materials.
Bitumen Penetration Test Method:
1-Test sample Preparation :
Soften the material to a pouring consistency at a temperature not more than 60°C for tars and 90°C for bitumen above the proximate softening point and stir it thoroughly till it`s homogeneous and free from air bubbles and water.
Pouring melt to the container to a depth min (10mm) in excess of the expected penetration. Protect sample from dust and allow it to cool in an atmosphere at a temperature between 15-30° C for one hour. Then place it along with the transfer dish in water bath at 25° ± 0.1 °C, unless otherwise stated.
2-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.
3-Clean the needle with benzene, dry it and load with the weight. Total moving load required is 100 ± 0.25 gms, including the weight of needle, carrier and super-imposed weights.
4- Adjust needle to make contact with the sample surface. This may done by placing needle-point in contact with its image reflected by bituminous material surface.
5- Make the pointer of the dial to read zero or note the initial dial reading.
6- Release the needle for exactly five seconds also.
7- Adjust the penetration machine to measure the distance penetrated.
8-Make at least 3 readings at points on the surface of the sample not less than 10 mm apart and not less than l0mm 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.
Iran bitumen manufacturing process:
Iran Penetration Grade Bitumen made by chosen crude oils via fractional distillation process. It heated to 300-350 C. Through vaporization, fed to distillation column allowing separate lightest fractions of crude, from heavier fractions, which remain liquid.
Higher boiling point bits are drawn – off via heat exchanger and enter vacuum distillation column. This produces also used to manufacture some grades of Iran bitumen.
Furthermore, pressure and temperature conditions within vacuum process will determine short residue hardness. It can also modified by air blowing. Air is passed throe residue at 250 – 300 degrees C.