Bitumen Specific Gravity Test: Definition and Procedure

Bitumen has an essential feature, which is its specific gravity. A bitumen specific gravity test determines it. There are some international methods of the Bitumen gravity testing, including ASTM D 70, AASHTO T 228, IS 1202, EN 15326, and IP 549. However, there are two common methods to test bitumen-specific gravity: the pycnometer method ( ASTM D70 ) and the balance method ( IS 1202 ). The specific gravity of bitumen has several critical impacts on its performance, especially in the asphalt density test for construction and the importance of bitumen grade consistency. It directly influences the durability, rutting resistance, temperature susceptibility, adhesion, and cohesion of the material and its performance. It is highly important to buy bitumen from a reliable supplier.

What Is the Specific Gravity of Bitumen?

A bitumen specific gravity test is done to determine the specific gravity in bitumen. It is the ratio of bitumen density compared to water density. Also, the temperature must be the referenced one, which is normally 4°C (39.2°F) or 25°C (77°F). This feature ranges from 0.97 to 1.02. The number 1.02 is for pure bitumen. As the specific gravity lowers, it means that there is a higher degree of impurities. However, lighter-grade bitumens have lower specific gravity as well. This property is critical for identifying the grade of bitumen, material specification, and bitumen quality control. (Source)

International Standard Methods of Bitumen Specific Gravity Test

Several different international standard methods of bitumen specific gravity tests exist. Here, you can learn more about each test.

• ASTM D 70: This standard testing method shows the specific gravity of bitumen. A pycnometer is used in this method, and the approach is based on the viscosity.

• AASHTO T 228: This standard method uses a pycnometer to determine the specific gravity of semi-solid and bituminous materials.

• IS 1202: IS 1202 is an Indian standard for determining the bitumen specific gravity test. This method uses a specific gravity bottle or a pycnometer.

• EN 15326: This is a European standard for bitumen density testing. It is used for bitumen and bituminous binders by using a pycnometer.

• IP 549: The Institute of Petroleum introduced IP 549. This method uses a pycnometer to determine the specific gravity of semi-solid bituminous materials.

Common Methods to Test Bitumen-Specific Gravity

Although there are some methods for performing the bitumen specific gravity test, two are common among all others. These methods involve several steps. The step-by-step process is below.

Pycnometer method ( ASTM D70 )

The pycnometer method is a standard laboratory method. A calibrated glass flask is normally used to measure the volume and mass of the bitumen sample. Lastly, the specific gravity is calculated at a reference temperature. The steps to perform this method are:

• The specific gravity flask or the calibrated pycnometer must be clean and dry.
• The empty pycnometer must be weighed to achieve its mass. Then name it M1.
• In this step, the bitumen sample is poured into the pycnometer. There must be no air bubbles inside the sample.
• The filled pycnometer must be weighed to determine its mass with the sample. Name it M2.
• Clean the pycnometer by removing the bitumen.
• In this step, the pycnometer must be filled with distilled water. Determine its mass with water and name it M3.
• The specific gravity can be calculated using this formula: (M2 – M1) / (M3 – M1).

Balance method ( IS 1202 )

The balance method, or IS 1202, is an Indian standard method. This method is performed by weighing the bitumen sample in air and water with the help of a balance. The differences in weights will help determine the specific gravity of bitumen. The steps to perform this standard method are:

• A clean and dry glass or metal vessel can be used. It must be weighed in the air to determine its mass, which we call A.
• The vessel gets filled with distilled water. It must be weighed in the air to determine its weight with water, which we call B.
• The water is removed from the vessel. It must be cleaned before pouring the bitumen sample.
• The second step is repeated. The vessel with the bitumen must be weighed in the air. Its mass with the bitumen sample is called C.
• The vessel with the bitumen sample must be suspended in water to calculate its mass, which we call D.
• The specific gravity is calculated using the formula (C—A) / (B—D).

Impact of Specific Gravity on Bitumen Performance

Referring to Bitumix, specific gravity has a considerable impact on bitumen performance. It is crucial to choose materials with proper specific gravity values. Bitumen’s specific gravity impacts its applications in pavement, construction, and maintenance.

Asphalt Density Test for Construction

The specific gravity of bitumen directly impacts the density of asphalt mixes in construction projects. This is a vital feature for determining their quality. It is essential to get asphalt density tests during construction to make sure the density of the mixture is proper for the application.

Importance of Bitumen Grade Consistency

Specific gravity is critical as it influences the consistency of bitumen grades. This factor directly affects temperature susceptibility, cohesion, adhesion, and overall performance. Consistent bitumen grades are important for achieving desired properties in projects with the proper quality and durability of the pavement.

Durability

As the specific gravity value gets higher, the durability and strength of the bitumen increase as well. The main reason is that the higher specific gravity means the material is denser, so it tolerates heavier loads.

Rutting Resistance

Rutting is pavement distress caused by the accumulation of permanent deformation, especially in wheel paths. Bitumen with a higher specific gravity can resist rutting better than other types.

Temperature Susceptibility

The specific gravity of bitumen generally impacts its susceptibility to temperature variations. A lower specific gravity value leads to excessive softening at higher temperatures, which increases the risk of rutting, while a higher specific gravity value causes increased stiffness, especially at lower temperatures. However, it must be treated carefully, as it might lead to cracking.

Adhesion and Cohesion

Adhesion and cohesion are two essential factors to ensure bitumen’s ability to bond with aggregates. It can maintain its structural integrity with the help of these properties, which are highly affected by the specific gravity of bitumen.

Conclusion: Choosing Reliable Bitumen Suppliers in the UAE

We learned that the bitumen specific gravity test is necessary for bitumen applications. Bitumen suppliers in the UAE must ensure these tests are taken care of. At YasminTrading, we have ensured that you receive the highest-quality bitumen to ensure a durable and safe application in your projects.