Classification of Bitumen
This “pen” test classification is used to indicate the hardness of bitumen, lower penetration indicating a harder bitumen. Specifications for penetration graded bitumens normally state the penetration range for a grade, e.g. 50/70. Other tests are used to classify the bitumen for specification purposes, such as softening point, solubility, flash point etc.
40/50
| Characteristic | value | Test Method |
|---|---|---|
| Specific Gravity @ 25/25 °C | 1.01-1.06 | ASTM D-70 |
| Penetration @ 25°C (dmm) | 40-50 | ASTM D-5 |
| Softening Point(°C) | 52-60 | ASTM D-36 |
| Ductility @ 25°C (cm) | 100 | ASTM D-113 |
| Loss on Heating (%wt) | 0.2max | ASTM D-6 |
| Drop in Penetration after Heating(%) | 20max | ASTM D-6&D-5 |
| Flash Point (°C) | 250min | ASTM D-92 |
| Spot Test | negative | A.A.S.H.O.T.102* |
*AMERICAN ASSOCIATION OF STATE HIGHWAY OFFICIALS .
BITUMINOUS BINDERS, PREPARATIONS
Bitumens are also used as a raw material to manufacture mixtures (preparations) with improved handling and application characteristics, or to enhance the physical properties. In such products bitumen is often the principal component, but they can contain significant proportions of other materials. These products are often referred to as bituminous binders or bitumen products, and are chemically classified as bitumen preparations. The three most commonly used are:
CUT-BACK BITUMEN
Cut-backs are bitumen preparations in which the viscosity of the binder has been reduced by the addition of a volatile solvent, normally derived from petroleum. Typically the solvents used are white spirit and kerosene. Cut-back products are typically used for spraying and some mixing applications.
Fluxed bitumen
Fluxed bitumens are bitumen preparation where the viscosity of the binder has been reduced by the addition of relatively non-volatile oils. Typical fluxants include gas oil and vegetable based oils.
MODIFIED BITUMEN
Modified bitumens are bituminous binders whose performance properties, such as elasticity, adhesive or cohesive strength, have been modified by the use of one or more chemical agents. These agents may be polymers, crumb rubber, sulphur and polyphosphoric acid, among other materials. Modifid bitumens are widely used in the production of roofing felt and in paving applications.
60/70
| Characteristic | value | Test Method |
|---|---|---|
| Specific Gravity @ 25/25 °C | 1.01-1.06 | ASTM D-70 |
| Penetration @ 25°C (dmm) | 60-70 | ASTM D-5 |
| Softening Point(°C) | 49-56 | ASTM D-36 |
| Ductility @ 25°C (cm) | 100 min | ASTM D-113 |
| Loss on Heating (%wt) | 0.2max | ASTM D-6 |
| Drop in Penetration after Heating(%) | 20max | ASTM D-6&D-5 |
| Flash Point (°C) | 250min | ASTM D-92 |
| Spot Test | negative | A.A.S.H.O.T.102* |
*AMERICAN ASSOCIATION OF STATE HIGHWAY OFFICIALS .
BITUMEN EMULSION
Bitumen emulsions are products in which tiny droplets (the dispersed phase) of bitumen or bituminous binder are dispersed in an aqueous medium (the continuous phase). The bitumen particle charge can be positive (cationic), negative (anionic), or uncharged (non-ionic) depending on the emulsifier employed. The binder can be either a bitumen, cutback, or modified bitumen. Bitumen emulsions are used largely in road surfacing applications, such as surface dressing, cold mixtures and slurry seals.
80/100
| Characteristic | value | Test Method |
|---|---|---|
| Specific Gravity @ 25/25 °C | 1.01-1.06 | ASTM D-70 |
| Penetration @ 25°C (dmm) | 60-70 | ASTM D-5 |
| Softening Point(°C) | 49-56 | ASTM D-36 |
| Ductility @ 25°C (cm) | 100 min | ASTM D-113 |
| Loss on Heating (%wt) | 0.2max | ASTM D-6 |
| Drop in Penetration after Heating(%) | 20max | ASTM D-6&D-5 |
| Flash Point (°C) | 250min | ASTM D-92 |
| Spot Test | negative | A.A.S.H.O.T.102* |
*AMERICAN ASSOCIATION OF STATE HIGHWAY OFFICIALS .
Asphalt is a mixture of a bituminous binder with mineral aggregate (stone), sand and filler, typically containing approximately 4-7%m bitumen.Asphalt is primarily used for road construction, the properties being dependent upon the type, size and amount of aggregate used in the mixture, all of which are adjusted to provide the required properties for the desired application.