Overview of Test Areas

Four different test areas were included in the test plan for evaluation. Table 4.1 contains a summary of the test area objectives and physical descriptions. Each test area had a different underlying pavement structure that was overlaid with UTW. Two different underlying composite pavements and two different

underlying HMA pavements were evaluated. Test Area 1 (TA1) consisted of two test lanes: one lane that was loaded by the APT carriage and a lane that was not

loaded by the APT carriage. In Test Area 2 (TA2) and Test Area 3 (TA3) all lanes were loaded. Test Area 4 (TA4) had test lanes with varying depths of UTW and HMA but these lanes were not loaded with the APT carriage. All test lanes were 4 feet (1200 mm) wide regardless of test lane.

Table 4.1 Test Area Summary (continued)

Test Area 1 Test Area 2 Test Area 3 Test Area 4

Table 4.1 Test Area Summary (continued)

HMA Layer

Table 4.1 Test Area Summary

Test Area 1 Test Area 2 Test Area 3 Test Area 4

UTW Concrete

Test Area 1 was constructed to evaluate the performance of UTW over a very stiff composite pavement. The test lanes of TA4 were constructed on the existing underlying composite pavement section previously used in the APT (Stiady et al. [2003]). This underlying composite pavement consisted of 4 feet (1200 mm) of pea gravel covered by approximately 8 inches (200 mm) of compacted clay used as a leveling course. Four, 12-inch (300 mm) thick reinforced concrete slabs, each 5 feet (1.5 m) wide were placed on top of the leveling course. These slabs contained a pipe system that was used to raise or lower the temperature of the HMA layers placed on top of the slabs as to provide a stiff layer to induce rutting on the HMA mixtures tested in the APT. The HMA layer used in the previous study was 4 inches (100 mm) thick composed of a Superpave surface mixture with PG 64-22 binder and was subjected to 20,000 APT, 9,000 lbs (40 kN) load passes of the APT carriage (single axle, dual tires).

Figure 4.2 Layout of TA1

To construct the UTW, one inch of the HMA was milled to completely eliminate the permanent deformations due to previous APT loadings as well as to provide a good bond between the HMA and UTW. The milling left the HMA layer

approximately 3.0 inches (75 mm) thick. The HMA was cleaned to produce a fully bonded condition (Section 4.3.6). A 10 foot (3000 mm) wide concrete slab, 2.5 inches (63 mm) thick was constructed as the UTW overlay using the base concrete mix (Section 4.3.5). The slab was sawcut to produce two, 4 foot wide test lanes. A 2 foot (600 mm) wide area was constructed along the edge of the

APT test pit to minimize the edge effects of the APT test pit boundary on the loaded lane. Each of the test lanes was subsequently saw-cut at four foot

intervals. The saw-cutting created 4 foot by 4 foot (1200 mm by 1200 mm) UTW panels in both the Lane 1(loaded) and Lane 2 (unloaded) test lanes (see Figure 4.2).

4.2.2. Test Area 2

The purpose of TA2 was to evaluate the performance of the UTW constructed over a more realistic underlying composite pavement from that used in TA1. As mentioned in Section 4.2.1., the underlying composite pavement in TA1 was designed to induce rutting in the HMA. The 12 inch (300 mm) reinforced concrete slab provided a very stiff pavement section that was not likely to be encountered in many pavements in Indiana. Thus, in preparation for the construction of the second composite pavement section, TA2, the APT test pit was completely emptied and cleaned. The test pit was filled with 46 inches (1200 mm) of pea gravel and an 8 inch (200 mm) layer of well-graded crushed limestone (INDOT gradation #53) was placed over the pea gravel. Next, a 6 inch (150 mm) thick plain PCC layer of using a standard INDOT concrete paving mix was placed over the crushed stone. The PCC layer was then overlaid by four HMA layers totaling 12.0 inches (300 mm). The HMA layers were Superpave intermediate and surface mixtures with PG 64-22 binder. In preparation for the construction of the UTW, the top 2.5 inches (63 mm) of the HMA was milled.

This left the HMA layer approximately 9.5 inches (237 mm) thick.

Figure 4.3 Layout of TA2

In total, five, 2.5 inch (63 mm) thick UTW test lanes were constructed. Each lane was poured separately. Three different concrete mixtures using a base UTW concrete (Lanes 1, 4, and 5), high early strength concrete (Lane 2), and a fiber reinforced concrete (Lane 3) were used in order to evaluate the performance of such mixtures when used in UTW applications. More detailed information regarding these mixes is provided in Section 4.3.5. Additionally, three different bonding conditions were created to evaluate the effect of full bonding (Lanes 1 through 3), partial bonding (Lane 4), and no bonding (Lane 5). More detailed information on these bonding conditions is presented in Section 4.3.6. The lanes were 4 feet wide (1200 mm) and were saw-cut into 4 foot by 4 foot (1200 mm by 1200 mm) panels. Figure 4.3 shows the layout of TA2.

4.2.3. Test Area 3

TA3 was constructed in order to evaluate the performance of UTW constructed on an HMA pavement. Again, the preparation of the underlying structure in TA3 involved the removal of the all the materials from the test pit and construction of an HMA pavement. The test pit was filled with 50 inches (1300 mm) of pea gravel which was covered with 8 inches (200 mm) of well-graded crushed

limestone (INDOT gradation #53). The 14 inch (350 mm) thick layer of HMA was then placed on top of the limestone. The HMA was placed in 6 lifts ranging from 2 inches to 3 inches (50 mm to 75 mm) in thickness. The HMA layers were Superpave base, intermediate, and surface mixtures with PG 64-22 binder.

After completion of the HMA placement, the top 2.5 inches (63 mm) of the HMA layer was milled to allow the construction of the UTW layer. This left the HMA layer approximately 11.5 inches (287 mm) thick which was used as a base on which the UTW layer was placed.

Figure 4.4 Layout of TA3

Similar to TA2, five, 2.5 inch (63 mm) thick UTW test lanes were constructed.

Each lane was poured separately. Three different concrete mixtures using a base UTW concrete (Lanes 1, 4, and 5), high early strength concrete and fiber (Lane 3), and a fiber reinforced concrete (Lane 3) were used in order to evaluate the performance of such mixtures. More detailed information regarding the composition of these mixes is contained in Section 4.3.5. Additionally, three different bonding conditions were created to evaluate the effect of full bonding (Lanes 1, 2, 3, and 4), partial bonding (Lane 5), and no bonding (Lane 5). More detailed information on these bonding conditions is presented in Section 4.3.6.

The lanes were 4 feet wide (1200 mm) and were saw-cut into 4 foot by 4 foot (1200 mm by 1200 mm) panels. The layout of TA3 is illustrated in Figure 4.4.

4.2.4. Test Area 4

The purpose of TA4 was twofold: to provide UTW pavement sections with varying thicknesses for design equation development and to evaluate the effect of environmental conditions on the UTW pavement. TA4 was placed in a parking lot outside the APT facility. The parking lot was constructed of HMA and was 7 inches (175 mm) thick. The test area was 20 feet (6100 mm) long by 20 feet (6100 mm) wide (see Figure 4.5). The milling of the HMA was as follows: a 2 inch milling depth in Lanes 1 through 3, a 3 inch milling depth in Lane 4, and a 4 inch milling depth in Lane 5. This left the thickness of the HMA at 5 inches in Lanes 1-3, 4 inches in Lane 4, and 3 inches in Lane 5. Five UTW test lanes were constructed at a width of 4 feet (1200 mm) each. The base concrete mix (Section 4.3.5) was used and the HMA was prepared to produce fully bonded conditions (Section 4.3.6). The thickness of the UTW also varied. The UTW in Lane 1 had a thickness of 4 inches (100 mm), Lane 2 had a thickness of 3 inches (75 mm), Lane 3 had a thickness of 2 inches (50 mm), Lane 4 had a thickness of 3 inches (75 mm), and Lane 5 had a thickness of 4 inches (100 mm). The UTW lanes were sawcut to produce panels that had dimensions of 4 foot by 4 foot (1200 mm by 1200 mm).

Figure 4.5 Layout of TA4