Samenvatting
Bitumen is an organic product, which is derived from selected crude oils. It contains natural anti oxidant agents. Even so, bitumen hardens (especially at the surface) with time due to the action of UV light, oxygen, and moisture. In asphalt, bitumen hardens even faster and more severely due to the relative thin binder film. This is especially so with asphalt mixes with low bitumen contents and high void contents, as in porous asphalts. Additionally severe hardening can occur during asphalt production and application, and this decreases the durability of asphalt. Therefore close control of the asphalt production and application conditions is required (e.g., at a max temperature of 175 degrees C).