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old standards
'''Binder''' is the new name for asphalt cements. It is the glue that holds the aggregate together and makes asphalt black. PG graded asphalt binder is a new method of specifying binder appropriate for the climate where the asphalt mixture is to be laid. The binder is tested to make sure it gives the greatest amount of flexibility during cold temperatures (to resist cracking) and the greatest amount of rigidity during warmer temperatures (to resist rutting).<br>The type of PG graded asphalt binder used depends on the temperatures of the area. For example, in Florida, binders need to be able to deal with extended periods of heat. In Alaska binders need to deal with prolonged periods of cold. In Wisconsin the binders need to have flexibility to deal with both types of climates.<ref>http://auto.ihs.com/document/abstract/BGMEIBAAAAAAAAAA</ref>
'''Binder''' is the new name for asphalt cements. It is the glue that holds the aggregate together and makes asphalt black. PG graded asphalt binder is a new method of specifying binder appropriate for the climate where the asphalt mixture is to be laid. The binder is tested to make sure it gives the greatest amount of flexibility during cold temperatures (to resist cracking) and the greatest amount of rigidity during warmer temperatures (to resist rutting).<br>The type of PG graded asphalt binder used depends on the temperatures of the area. For example, in Florida, binders need to be able to deal with extended periods of heat. In Alaska binders need to deal with prolonged periods of cold. In Wisconsin the binders need to have flexibility to deal with both types of climates.<ref>http://auto.ihs.com/document/abstract/BGMEIBAAAAAAAAAA</ref>
===Grades===
Not all agencies have adopted SuperPave mix design technology or the PG graded asphalt binder system, and continue to use the old terminology for describing asphalt binders. The following describes three methods still widely used to describe asphalt binders:
All of the above methods of describing the asphalt binder are based on some measure of the asphalt viscosity.
For Example:
'''Penetration Grades''' (such as pen 85 -100) is based on how deep a needle will push into the asphalt under a certain weight and at a certain temperature. Viscosity Grades are based on the measured viscosity at a certain temperature, and AC Grades are also based on measured viscosity, but after aging or hardening the asphalt in an oven to simulate the effect of heat on the asphalt during making of the mixture.
'''Compaction:''' This is the process of densifying the HMA while it is in a hot, pliable state, to pack the aggregate particles together and to remove as much of the air voids as possible. Compaction gives the mix strength, resistance to rutting (i.e. resistance to additional densification under the action of vehicular traffic), it seals the surface from the ingress of water, and gives a smooth riding surface.
During compaction of asphalt hot mix three very important factors that will affect pavement performance take place. The asphalt coated aggregate particles are pressed together, air voids are reduced, and mix density (weight to volume ratio) increases.<ref>http://www.trb.org/news/blurb_detail.asp?id=3405</ref>
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[[Category:Construction]]
[[Category:Construction]]