The project in North Yarmouth was for an approach fill at a bridge on Route 231.  The project was initiated to determine the effect of tire shred fill on pavement as well as the effect of tire shreds on ground water quality when the fill is placed above the water table.     The test area was divided into sections and included a control area without tire shred fill.  One section included type B tire shreds with a maximum particle size of 12 inches.  The other three test sections included type A shreds with a maximum size of 3 inches.  Table 1 gives the thickness of each layer of material including the tire shreds, borrow cover, subbase course aggregate, and surface course pavement.  Geotextile was used to completely separate the tire shreds from the surrounding soil.  Figures 8 and 9 give cross sections of the test and control sections.

Table 1. Summary of North Yarmouth Test Section Configuration

Section	Tire shred type	Thickness of layer (in.)
		Tire shreds	Borrow Cover	Subbase course	Surface course
1	B	24	5	25	5
2	A	24	17	25	5
3	A	24	29	25	5
4	A	24	5	25	5
Control	----	----	5	25	5

Figure 1. North Yarmouth field trial - longitudinal section (Nickels, 1995)

Figure 2. North Yarmouth field trial - cross section (Nickels, 1995)

 

The tire shreds used in this project were spread in 12 inch lifts with a medium-sized bulldozer.  The type A shreds spread well and could easily be placed at the desired thickness.  The type B shreds had oversize pieces that made spreading more difficult.     To compact the tire shreds, different types of compaction equipment were used to determine the best method.  The vibratory smooth drum roller, bulldozer and vibratory tamping foot roller all worked equally well at compacting the tire shred fill.  A loaded dump truck was ineffective, as it sank into the tire shreds, but didn't compact the material well.     After compaction, but before overlying soil was placed, the total unit weight was 43 pcf for the type A 3-in. shreds and 38 pcf for the larger type B shreds.  In total, the fairly small scale project utilized about 100,000 scrap tires.

Pavement Deflections

Pavement Tensile Strains

Environmental Properties