Determination of Non-Soluble Matters in Asphalt
Introduction
Asphalt is an important material used in pavement construction. Quality of asphalt directly affects the service period and performance of pavement. The non-soluble matters content of asphalt is an important factor affecting the quality of asphalt. Non-soluble matters are the substances in asphalt that are insoluble in the tested solvent(s). They consist mostly of mineral matter, such as sand, gravel, silica and alumina, as well as other inert substances such as iron and calcium oxides. The content of non-soluble matters in the asphalt is an indicator of the quality of the asphalt mixture.
In this article, the method of determining the content of non-soluble matters in asphalt is discussed. This method is based on the American Standard ASTM D 1730.
Methodology
Materials
The materials required for this test are:
• An asphalt sample of known weight
• A solvent, such as toluene or xylene
• A vacuum oven
• An analytical balance
Procedure
1. An asphalt sample of known weight is taken, and then placed in the vacuum oven.
2. The oven is set to 110°C, and the sample is left to dry for 10 minutes.
3. After drying, the sample is removed from the oven and cooled.
4. An aliquot of solvent, such as toluene or xylene, is then added to the sample and stirred.
5. The mixture is then allowed to settle for 20 minutes.
6. The supernatant solvent is then decanted and discarded.
7. The residue is then dried in the vacuum oven for 10 minutes at 110°C.
8. After drying, the sample is cooled and weighed on an analytical balance.
9. The weight of the non-soluble matters (NSM) is calculated by subtracting the weight of the sample before drying from the weight of the sample after drying.
Results
The weight of the non-soluble matters (NSM) is given in percentage, calculated using the following equation:
NSM% = (Weight of the Non-soluble Matters / Weight of the Sample) x 100
Conclusion
The method described in this article is widely used to determine the content of non-soluble matters in asphalt. This method is based on the American Standard ASTM D 1730. In this method, an aliquot of solvent is added to the sample and mixed, and then allowed to settle. The supernatant solvent is then discarded and the residue is dried and weighed. The weight of the non-soluble matters is then calculated.
