Superpave 12.5 mm gradient and mesh crumb rubber were used to create an asphalt-rubber hot mix asphalt (AR-HMA) design at 20% of the total weight of the asphalt binder during the evaluation. At this time, asphalt rubber is only used on HMAs with a more open grading nature, such as Open Graded Friction Courses (OGFC). However, OGFCs are of limited use due to potential problems (i.e., clogging and winter maintenance). However, the 12.5 mm Super pow mix can be used on nearly any road in New Jersey and is most commonly used as a surface course. Available for both new construction and renovation projects. Therefore, this mixed type has the highest potential for use, meaning more tires can be recycled in the end. However, he must consider two factors before approval. performance and cost. In this study, four of his HMA blends were manufactured and tested. Three baseline mixes using PG64-22, PG70-22, and PG76-22 asphalt binders and an AR-HMA mix using rubber mixed with the same PG64-22 asphalt binder. The effect of crumb rubber particle size on compression properties was also evaluated during the mix design process. This provides a way to compare the final mixing performance of different performance grade binders on AR-HMA mixtures. This type of mixing test method is necessary to ensure that the crumb rubber complies with the overall gradient volume limit, and how the crumb rubber during performance testing interacts with this volume limit. 
Therefore, several different performance tests were performed on four different HMA blends: 1) Cyclic Load Permanent Deformation Test using an Asphalt Pavement Analyzer, 2) Simple Performance Test Specification, 3) dynamic modulus, 4) cyclic shear at constant altitude, 5) frequency sweep at constant altitude, and 6) simple shear at constant altitude. Results from the mixed design part concluded that the maximum grain size should not exceed #30 mesh to provide consistent compactness when using crumb rubber in a 12.5 mm Superpave design. Performance testing concluded that the AR-HMA blend performed as well or better than his PG76-22 in each test conducted. For example, dynamic modulus test results showed that AR-HMA exhibited the same hardness as PG76-22 at higher test temperatures, but AR-HMA had much lower hardness at lower test temperatures. This indicates that his ARHMA blend design in this study offers good rot resistance while also providing good cold crack resistance. Essentially, adding crumb rubber to PG64-22 increased the working temperature range of the asphalt binder, both on the high and low sides. Additionally, performing similarly to PG76-22 allowed Bayshore Recycling to establish a cost comparison using his HMA cost difference between PG64-22 and PG76-22. 
- Performance Test Past experience has shown that adding crumb rubber to hot mix asphalt (HMA). It can really improve the overall working characteristics of the HMA. It has been shown to increase asphalt binding capacity. Oxidation fights aging more easily. Can be further decomposed at temperature Categories where HMA works. - High Temperature At high temperatures, the asphalt binder easily falls off due to natural reduction. Viscosity associated with high temperature. This position creates a "soft" HMA perishable. By including crumb rubber in HMA, Increases viscosity contribution and cures HMA at higher temperatures. - Intermediate Temperature At intermediate temperatures, the HMA must be able to withstand cyclic loading. Reduces tensile strain. Tensile strain occurs at the bottom of the asphalt layer excessive flexion and upward movement (called reflex cracking). Finally, the structural integrity of the HMA layer is compromised. By adding crumb rubber HMA increases ductility within the layer and increases resilience. Work done by Gopal (2001) concluded that the addition of pieces. Because rubber aids the energy absorption properties of her HMA, possibility of failure due to repeated load. However, the authors also recommend: you need to determine the best rubber material for each size of crumb rubber. 
Asphalt binder type.
- Low Temperature At low temperatures, the HMA should not be too hard. HMA due to its high modulus at low temperatures, it is very fragile. Therefore, to help resist cracking at low temperatures, HMA has a low hardness and high creep. Creep is defined as the deflection of her HMA under constant load. Some researchers' results show mixing both crumb rubbers lowers stiffness and enhances creep properties of HMA. - Asphalt Pavement Analyzer (Apa) APA is the second generation Loaded Wheel Tester (Figure 3 and Figure 4). It is the ability to test solid brick or pellet samples in a variety of environments. Both rut (high temperature permanent deformation) and fatigue (low) conditions temperature crack). This device can also be connected to a computer and data acquisition allows the user to measure her HMA's routing per load cycle. The wheel load is approximately one cycle per second in inches billed at a rate of a pressure tube placed over the HMA specimen and Simulate (small scale) traffic load that normally occurs in the field. 
However, no one has ever attempted to directly compare APA results with actual routing have been successful. Therefore, the main use of this tool is as a mixing comparison tool. Selection (that is, choosing the least spoiled mixture from the APA test). APA is typically run at a test temperature of 64oC. Sample is conditioned at this temperature for at least 4 hours before testing. Now loading a commonly used configuration within APA is a 100 lb wheel load and hose the pressure is 100 psi, but some other researchers have had success with higher pressures. Both the APA User Group and the National Asphalt Technology Center recommend using 100 psi hose pressure at 100 pounds wheel weight and one-time conditioned samples are subjected to 25 cycles of seating load. After 25 cycles once done, measure the depth of the first rut. Tests are usually continuing at least 8,000 cycles have been completed. Difference between initial route and final route depth measurements are calculated as APA rattling depths.