Modified binders have the ability to
offer improved performance over conventional binders. Benefits that may be
derived from binder modification and typical conditions where such binders
should be considered, the polymer dosages and mix designs of the binder are
selected, to ensure optimum performance to the climatic and traffic conditions
that, prevail on a particular project. Their main application is waterproofing.
Extensive research has shown that, the use of performance asphalts using
polymer modified bitumen binders significantly increases stability and strength
properties and longer life-span, as demanded by the industry to meet today’s
and tomorrow’s traffic conditions. Two methods are commonly used to incorporate polymers into asphalt. Polymer- bitumen emulsion that is relatively easy and trouble
free. Addition of solid polymers to asphalt with agitator. This method
normally requires substantial mixing and shearing in order to uniformly disperse
the polymers, particularly when SBS or SIS block copolymers are used.
Some benefits of PMB are higher resistance to weight or pressure, surface
remains smoother for longer time, resistance of aging due to high temperatures,
less cracking in low temperatures and less affected by moisture over time.The
PMB can be categorized into two board classes.
The main ingredient of these bituminous
membranes is refined bitumen and the basic polymerispolymerized (Styrene Butadiene Styrene).
The addition of elastomeric materials (SBS) makes the mixture more elastic, and
thus able to adjust more easily to any compressing and expanding that may
occur, while at the same time it is extremely resistant to low temperatures.Membranes
are reinforced with a polyesteric non-woven fabric, which gives to the final
product good mechanical strengths, as for instance tensile strength,
dynamic and static compressive strength. Coating of the membranes, that are intended for the final layer of a water
insulating system, with mineral gravels, protects them from the ultraviolet
rays and helps increase their life span. ASTM test method is common for
these kinds of bitumen. Some additives which are common to use are Styrene – butadiene – styrene
(SBS), Styrene – butadiene – rubber Natural
rubber and Crumb tire rubber.
main ingredient of these bituminous membranes is refined bitumen and the basic polymeris atactic polypropylene.
The addition of plastomeric polypropylene resins (APP) makes the mixture more
plastic and resistant to high temperatures and ultraviolet radiation. Some of
the common additives are atactic polypropylene
(APP), polyethylene (PE), polypropylene (PP), polyvinyl chlorid.