Recycling and Reclamation of Asphalt Pavements Using In-Place Methods (2011)

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3 FIGURE 1 Pavement condition and type of in-place recycling method (Faster 2007). A number of benefits can be realized with the use of in- place recycling processes. These options provide economical and sustainable solutions that reduce demand on raw mate- rials, energy consumption, and production of greenhouse gases, while maintaining functionality and performance. Advantages include the following: • Construction benefits – Minimizes traffic disruptions – Shortens lane closure times – Maintains height clearances • Pavement condition improvements – Improves friction – Minimizes edge dropoff concerns – Reduces surface irregularities and distress type, severity, and extent – Addresses some existing material problems such as moisture damage • Environmental benefits – Conserves nonrenewable resources – Reduces emissions – Reduces fuel consumption – Reduces number of haul trucks – Eliminates materials generated for disposal • Cost benefit – Provides economical methods for pavement preser- vation and maintenance CHAPTER ONE INTRODUCTION BACKGROUND In recent years, petroleum and aggregate economics and sup- ply have increased the need for high-quality, cost-effective alternatives to virgin paving mixtures. Transportation pro- fessionals are asking for methods that optimize the value of in-place materials while minimizing traffic congestion and the environmental impact of paving operations. In-place recy- cling and reclamation enable agencies to optimize the value of in-place materials and minimize construction time and traffic flow disruptions, as well as to reduce vehicle emissions from long traffic queues. In-place recycling and reclamation also reduce the number of construction vehicles moving in and out of the construction area and neighborhood truck traffic. Current pavement recycling and reclamation methods answer all of these needs, particularly the following: • Hot in-place recycling (HIR) – Resurfacing – Repaving – Remixing • Cold in-place recycling (CIR) • Full-depth reclamation (FDR) Different methods of recycling are applicable to different types, levels, and severity, and hence different periods in the pavement life (Figure 1). Typically, HIR is used when the majority of the pavement distresses are minimal and limited to the upper few inches of the surface of the roadway with no evidence of structural problems (i.e., longitudinal cracking in wheel path, alligator cracking, and edge cracking). CIR is used when there is a higher number, type, and severity of non-load-related distresses that may extend farther down from the surface. CIR with an overlay can be used to address some load-related distresses. FDR is an in-place rehabilita- tion process that can be used for reconstruction, lane widen- ing, minor profile improvements, and increased structural capacity by addressing the full range of pavement distresses. The anticipated depths of the distresses, combined with the overall existing asphalt pavement thickness, are used to identify the type of in-place recycling process(es) that can be expected to extend the life of the pavement most economically.

4 few states have implemented HIR in recent years. Between 14 and 18 states have more than 10 years of experience. TABLE 3 AGENCY EXPERIENCE WITH IN-PLACED RECYCLING METHODS Question: Indicate how long you have been using each type of in-place recycling. Years of Experience Type of In-Place Recycling Used HIR CIR FDR <5 MO, NV DE, MO, NC, ND, OR, UT AL, DE, MO, NC, NY, VA, WY 5 to 10 AZ, GA, IL IL, WY AK, CA, CO, GA, IL, IA, MN >10 AR, ON, CO, FL, ID, IA, KS, KY, MD, MT, NC, NE, NY, TX, WA AZ, CA, CO, CT, ID, IA, KS, MN, MT, NE, NH, NV, NY, RI, SD, VT, WA, WI CA, CT, ID, MT, ND, NE, NH, NV, SC, SD, TX, UT, VT, WI We Don’t Use AK, AL, CT, DC, DE, IN, MN, ND,NH, NJ, OR, RI, SC, SD, TN, UT, VT, WI, WY AK, AL, AR, DC, FL, GA, IN, KY, NJ, SC, TN, TX AR, DC, RL, IN, KS, KY, NJ, OR, RI, TN TABLE 4 NUMBER OF LANE-MILES PER YEAR THAT ARE RECYCLED BY EACH METHOD Question: Indicate the extent of your annual recycling program in lane-miles. Lane-Miles Recycled Type of In-Place Recycling Used HIR CIR FDR <50 AR, CA, CO, FL, IL, IA, KS, KY, MT, NC, NE, NV, NY, TX, WY AZ, CA, CO, CT, DE, ID, IL, IN, KS, MN, MT, NE, NH, OR, RI, SD, TN, TX, UT, VT, WA, WY AL, CO, CT, DE, GA, IL, IN, IA, MN, MO, MT, NH, NY, OR, RI, SD, TN, TX, UT, VA, VT, WI 50 to 100 CO MO, NE, NY AK, CA, ID, ND, NE, NV >100 KS IA, NV, WI CA, SC Figures 2 and 3 summarize state responses for the in-place recycling processes and the size of their annual programs. Also included in these figures is the maximum traffic level states consider acceptable for each process. These figures show that the use of HIR and FDR is distributed across the United States. However, CIR is noticeably missing from use in the Southern and Southeastern states. Reasons for the lack of use of CIR in the Southern and Southeastern states are likely related to weather conditions (e.g., humidity, temperature, rainfall) and should be identified in future research programs. IN-PLACE RECYCLING PROGRAMS IN THE UNITED STATES The status of in-place recycling use across the United States was assessed using an online survey (Appendix A). The sur- vey collected information from “choose all that apply” ques- tions and open-ended requests for experiences. Responses were received from 45 states, although not all states had experiences with in-place recycling (Table 1). A total of 34 of the 45 states and one Canadian providence (Ontario) indi- cated experience with both HIR and CIR projects, and 33 of the 45 indicated experience with FDR projects. Of the states with experience using HIR processes, HIR remixing was the most frequently used (Table 2). TABLE 1 NUMBER OF AGENCIES AND CONTRACTORS WITH EXPERIENCE* In-Place Recycling Method States with Experience Contractors with Experience HIR 34 24 CIR 34 24 FDR 33 28 *Agencies may use one or more of the methods. TABLE 2 TYPE OF HIR USED BY AGENCIES Question: What types of hot-in-place recycling do you use? Type of HIR Used Surfacing Repaving Remixing AR, CA, CO, FL, IL, IA, KS, KY, MT, NC, NE, NV, NY, TX, WY AR, AZ, CO, FL, KS, KY, MO, NC, TX, WY AR, AZ, CA, CO, FL, ID, IA, KS, KY, MD, MO, NC, NY, TN, TX, VT, WA, WY The Asphalt Recycling and Reclaiming Association (ARRA) membership list was used to identify contractors to invite to complete the same survey. Of the membership list, 50 members were identified as contractors. In this case, companies providing materials and services for in-place recycling processes included asphalt contractors (e.g., for overlays) and aggregate producers. A total of 33 completed surveys were received. Responses were sorted by experience with a specific in-place recycling process (Table 2). Not all respondents had experience with all three methods. The years of experience with a recycling process (Table 3) and the number of lane-miles typically paved per year were evaluated (Table 4). The number of states with fewer than 10 years of experience represents the potential growth of in- place recycling in the United States. FDR use has grown sub- stantially over the past decade, followed by CIR use. Only a

5 FIGURE 2 Use of HIR and CIR processes, size of programs (lane-miles per year), and maximum traffic levels acceptable for roadways. FIGURE 3 Use of FDR processes, size of programs (lane-miles per year), and maximum traffic levels acceptable for roadways.