The Bitumen Softening Point Test - Ring and Ball Procedure
Bitumen is a complicated substance without a clear melting point. The bitumen gradually softens and loses viscosity as the temperature rises; therefore the softening point is established.
What is the bitumen's softening point? The temperature at which bitumen softens past a certain softness is known as the softening point of bitumen. The softening point test will reveal it.
To learn more about the bitumen softening point test and related procedures, watch the video below.
Ring and Ball Test
The ring and ball test is the method used in laboratories to determine the softening point. In this test, two
brass rings with steel balls are put over the bitumen sample. The system is heated and submerged in water. The softening point temperature is the temperature at which a bituminous coated steel ball strikes the bottom of a glass beaker.
Ring and ball equipment can be used to determine the softening points of smooth native Bitumen, road bitumen, coal bitumen, and blown bitumen. The softening point and penetration test are used to distinguish between hard bitumen and oxidized (blown) bitumen.
In general, the temperature susceptibility decreases as the softening point increases. In other words, there is greater heat resistance.
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Here is an illustration of a bitumen grade's softening point using the Indian Bureau's standard procedure (IS 1205):
What justifies a bitumen softening point test?
The softening point test chose bitumen based on its temperature resistance to choose the optimal bitumen binder for the requisite weather conditions for building roads.
Bitumen is used in hot areas since it has a greater softening point and should be more resistant to high temperatures. In other words, if the softening point value is lower than the pavement temperature, the bitumen in the layer will be soft and sticky.
On the other hand, colder regions use low temperature resistant bitumen.
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Bitumen Penetration and Softening Point Relationship
Viscosity grade bitumen and penetration grade bitumen typically have a lower softening point as penetration rises. Softer bitumen has a lower thermal resistance and gradually melts at lower temperatures.
Viscosity also raises the softening point. This indicates that at increasing temperatures, thick bitumen begins to melt. As a result, as viscosity increases, the temperature susceptibility declines.
At the softening point, a bituminous coated steel ball strikes the bottom of a glass beaker.
The link between the softening point and the depth of penetration in oxidized (blown) bitumen is ambiguous. Depending on the production technique.
This sort of bitumen has a higher softening point than penetration and viscosity grade bitumen. As a result, oxidized bitumen is less vulnerable than viscosity and penetration bitumen kinds.
International Standards for Bitumen Softening Point Test Methods.
The following conventional techniques are offered to ascertain the bitumen softening point:
The following standards are available: ASTM D36 | ASTM E28-67/E28-99 | ASTM D6493-11 | IS 1205 | EN 1427 | IP 58, ISO 4625 | JIS K 6863.
Here is a description of the ring and ball test using the ASTM D36 methodology.
Bitumen Softening Point Test per ASTM D36:
Following are the parts of the ring and ball equipment and the test procedures:
The equipment includes:
Two Brass Rings | Two Steel Balls | Thermometer | A Glass Beaker | A Heater | Ring Holding Bases (Support)
Sample Preparation:
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The bitumen sample should be heated to a temperature between 75 and 100 °C until it is entirely liquid.
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Glycerin and dextrin should be prepared in an equal combination. Next, coat the metal or glass plate's surface. This stops the bitumen from clinging to the plate
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Raise the rings' temperature to a point close to that of the molten bitumen. Put them on a plate that has been covered in the glycerin and dextrin mixture.
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Pour a small amount of heated bitumen over each ring's internal volume. At room temperature, allow them to cool.
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With a little hot knife, the excess bitumen can be eliminated when the test pieces have cooled.
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The Bitumen Softening Point Test Method
Procedure
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Boil distilled water to a constant temperature of 5 °C and pour it into the water bath.
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Fix the bitumen-filled rings to the support frame and submerge them for 15 minutes at 5 °C in a water bath. The steel balls should be cooled to a 5 °C temperature.
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Put a steel ball atop the rings that are fastened to the support. This mixture should be put in a beaker of distilled water. At least 50 mm must separate the water's surface from the top of the ball.
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Adjust the stirrer and thermometer before placing the beaker on the heating. Permit the beaker to warm up at a constant pace of 5 +/- 0.5 °C/min.
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Heat the bitumen further until it softens, and the weight of the ball causes it to begin to fall.
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When each ball strikes the plate bottom, record the temperature recorded by the thermometer.
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The softening point of bitumen is equal to the average of the softening points of two balls, rounded up to the nearest 0.5 °C.
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The rings have a surface that is coated in a combination of glycerin and dextrin and contains bitumen..
The maximum discrepancy between the two values should not be greater than 1 °C for bitumen with softening points between 40 and 60 °C. The difference should be less than 1.5 °C for the softening point between 61 and 80 °C. The test must be redone if it is invalid.
Bitumen Softening Point Test Conclusion:
Bitumen's softening point is determined since it lacks a known melting point. We gauge the softening point using ring and ball equipment. Knowing what types and grades of bitumen can be utilized in various weather situations is helpful.