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Pavement Design ~ What is Rubber Asphalt?
Asphalt rubber is a mixture of 20% crumb rubber particles derived from the grinding of waste tires with 80% paving grade asphalt. The resultant hot mixture is added to a specially graded aggregate in a hot plant. This hot mix is either a gap graded (AR-AC) or open graded AR-ACFC) mix used to pave Arizona highways.
The table below shows how many tons of asphalt rubber hot mix and the number of projects constructed since 1988. The AZ Asphalt Rubber Projects is a complete list of projects for each year sorted by route and milepost. |
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| Year |
Tons Mix |
No. Of Projects |
| AR-AC |
AR-ACFC |
AR-AC |
AR-FC |
1988 |
0 |
4,080 |
0 |
1 |
1989 |
45,334 |
6,830 |
3 |
1 |
1990 |
22,178 |
78,529 |
3 |
5 |
1991 |
14,997 |
18,650 |
4 |
3 |
1992 |
23,530 |
106,970 |
3 |
10 |
1993 |
57,117 |
116,486 |
4 |
12 |
1994 |
51,545 |
136,703 |
5 |
14 |
1995 |
144,359 |
196,826 |
11 |
30 |
1996 |
124,290 |
122,947 |
7 |
21 |
1997 |
219,492 |
115,696 |
9 |
22 |
1998 |
396,601 |
376,814 |
13 |
39 |
1999 |
421,781 |
266,133 |
10 |
38 |
2000 |
271,863 |
206,578 |
16 |
38 |
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| Totals |
1,793,087 |
1,753,242 |
88 |
234 |
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The diagram below shows the process of converting waste tires into asphalt rubber hot mix. Of the five million waste tires annually produced in Arizona approximately 75% go into Arizona pavements under the jurisdiction of state, county, city or federal government. |
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Why use Rubber Asphalt?
Placement of AR-AC using a laydown machine |
Asphalt rubber is engineered to be used in the surface courses of most major Arizona State highways. It provides a very durable surface, with less cracking, a smooth, safe, cost effective and quiet riding surface. All these surface attributes are consistent with ADOT’s goal of providing a quality pavement to the traveling public.
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I-40 east of Flagstaff before AR-ACFC placement |
I-40 east of Flagstaff after AR-ACFC placement |
In addition, asphalt rubber pavements are environmentally friendly. A two inch resurfacing project with asphalt rubber uses over 2,000 waste tires per lane mile. Thanks to the good efforts of Materials Group, District Construction and numerous contractors, ADOT since 1988 has successfully engineered the use of over 10 million recycled waste tires into over 2,500 miles of state highways. For more information about asphalt rubber contact any of the Materials Pavement Design Team. |
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