| Asphalt or bitumen is still the best known
waterproofing material. However, it has poor aging characteristics, is brittle in cold
weather and fluid in hot weather and has no resistance to fatigue. Elastomeric compounds
such as SBS (Styrene-Butadiene-Styrene) substantially improve these properties. SBS rubber
is flexible and has the memory to return to its original form. SBS forms a rubber matrix
of butadiene when blended with asphalt. The styrene end blocks act as links holding the
elastomeric matrix together. The styrene and butadiene matrix increase the flow
characteristics and improve the low temperature flexibility and fatigue resistance of
roofing asphalt. |
SBS Modified bitumen performs even after 10,000,000 cycles of fatigue
testing, while blown bitumen and APP modified bitumen fail in the early stages.
|
