Asphalt

The primary use of asphalt is in road construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt and for sealing flat roofs. The terms //asphalt// and //bitumen// are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, asphalt (or asphalt cement) is the carefully refined residue from the distillation process of selected crude oils. Outside the United States, the product is often called bitumen. Natural deposits terminology also sometimes uses the word bitumen, like the La Brea Tar Pits. Naturally occurring asphalt is sometimes specified by the term "crude bitumen"; its viscosity is similar to that of cold molasses .whilst the material obtained from the fractional distillation of crude oil [boiling at 525 °C (977 °F)] is sometimes referred to as "refined bitumen". Asphalt is one of the indispensable materials of life in America--94 percent of the paved roads in America are surfaced with asphalt. Asphalt hurts when you fall off your bike. There have been many naturally occurring deposits of bitumen in the past and many of the deposits are put under heat and pressure.It was used as a sealant for waterproofing buildings. In the united states it was used by the indigenous people before Columbus even arrived.
 * Asphalt,** also known as **bitumen**, is the sticky, black and highly viscous liquid or semi-solid present in most crude petroleums and in some natural deposits; it is a substance classed as a pitch . Until the 20th century, the term **asphaltum** was also used.
 * History:**

The substance is completely soluble in carbon disulfide, and composed primarily of a mixture of highly condensed polycyclic aromatic hydrocarbons; it is most commonly modelled as a colloid, with asphaltenes as the dispersed phase and maltenes as the continuous phase (though there is some disagreement amongst chemists regarding its structure). One writer stated although a "considerable amount of work has been done on the composition of asphalt, it is exceedingly difficult to separate individual hydrocarbon in pure form", and "it is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large". Most natural bitumens contain sulfur and several heavy metals, such as nickel, vanadium, lead, chromium, mercury, arsenic, selenium, and other toxic elements. Bitumens can provide good preservation of plants and animal fossils.
 * Chemistry:**

1) dig about 8 inches into the ground where you will be putting the asphalt. this is so you have a level and solid base. 2) From there our next step is to lay down about 5 inches of gravel. A wheelbarrow works well when moving the gravel. once you have laid it out, level it with a rake or something of the sort. 3) Next, lay about 3 inches of aggregate (sand and rock mixture) on top. proceed to level this too. 4) Hopefully you have already bought the asphalt mix at the store because now you pour the hot mix onto of the gravels and level it. (use a spade) 5) Again, lay a thin layer of finer gravel and pave until it is smooth.
 * The process of making asphalt:**

This process may take a while to perform and complete and it will also require a significant amount of costly material. In the long run it will be far more durable that just layer down losse gravel of something similar. The LEED Green Building Rating System serves as a scorecard for the design, construction, and operation of green buildings. Pavement type selection (concrete vs. asphalt), on its own, can contribute directly to some LEED credits. Credits can be earned in these ways: When all these factors are considered, asphalt pavements can contribute more LEED credits than other pavement types.
 * Asphalt doing good for the environment!**
 * Porous asphalt systems earn credit for storm water management.
 * Light-colored asphalt helps to mitigate the urban heat island effect.
 * The ability to recycle asphalt pavement and the use of asphalt with high percentages of RAP (reclaimed asphalt pavement) make asphalt eligible for credits under the materials and resources heading.
 * The fact that asphalt pavement material is produced locally can earn credits for materials and resources.
 * Warm-mix asphalt offers several advantages which support sustainable development.

__**Safety and Health Topics**__
Exposure to asphalt fumes can cause serious injury and permanent damage. Workers that may be exposed to asphalt fumes need to be aware of the potential hazards in their work environment. Health effects from exposure to asphalt fumes include headache, skin rash, sensitization, fatigue, reduced appetite, throat and eye irritation, cough, and skin cancer. I once witnessed someone crash on a long board on asphalt and he still showed up to school the next day. It was scary.

 The use of recycled materials is at an all-time high; largely because of the savings in materials costs available to asphalt mix producers. Given the successful performance of most of these mixtures, the use of recycled materials will likely continue to grow.

THE CHEMISTRY OF ASPHALT

The substance is completely soluble in carbon disulphide, and composed primarily of a mixture of highly condensed polycyclic aromatic hydrocarbons; it is most commonly modeled as a colloid, with asphalts as the dispersed phase and maltenes as the continuous phase (though there is some disagreement amongst chemists regarding its structure). One writer stated although a "considerable amount of work has been done on the composition of asphalt, it is exceedingly difficult to separate individual hydrocarbon in pure form", and "it is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large" Most natural bitumens contain sulfur and several heavy metals, such as nickel, vanadium, lead, chromium, mercury, arsenic, selenium, and other toxic elements. Bitumens can provide good preservation of plants and animal fossils.