Practice and Performance of Cold In-Place Recycling and Cold Central Plant Recycling (2021)

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89   A web-based survey was developed to collect information about the following: • Experience with CCPR and CIR processes • Knowledge of, and experience with, new CCPR and CIR standards • Size of the existing cold recycling program • Typical traffic levels on cold recycled projects • Barriers to increased use of cold recycling processes A total of 40 responses were received for a response rate of 80%; only one response per agency was included in the analysis. The percentages of agencies responding to each question are based on a fixed total response rate of 40 agencies to provide a common baseline for each column and row. Not all respondents answered all questions. When respondents indicated they did not use CCPR and CIR processes in their state, they rarely answered any further questions. While CCPR and CIR processes are still not widely used at the state agency level, those agencies that do have experience frequently provided additional comments for each survey question. This chapter presents the percentage of responses, information on individual agencies responding to the questions, and a summary of the additional comments. The first question collected information about the respondent. Experience with CCPR and CIR Processes Question 2 asked respondents to “Indicate if you use either of these recycling methods in your area and, if used, how long have you been using each type.” The results are shown in Table 53 and Table 54 and in Figure 42, Figure 43, Figure 44, and Figure 45. A summary of additional comments for this question shows the following: • Cold recycling is only used by local agencies (2 agencies). • Several agencies are interested in trying cold recycling soon (4 agencies). • Several agencies have used cold recycling but only sporadically and only for a few projects (5 agencies). • One agency used to use emulsions but now uses only foamed asphalt (1 agency). • One agency uses only emulsions with CIR (1 agency). C H A P T E R 3 Agency Survey

90 Practice and Performance of Cold In-Place Recycling and Cold Central Plant Recycling Recycling Agent and Method of Cold Recycling Less than 5 years 5 to 10 years More than 10 years We don’t use this method Total Responses per RowPercent Responses Percent Responses Percent Responses Percent Responses CCPR with emulsions 10% 4 5% 2 3% 2 45% 18 25 CCPR with foamed asphalt 3% 1 13% 5 3% 1 45% 18 25 CIR with emulsions 5% 2 23% 9 40% 16 28% 11 38 CIR with foamed asphalt 8% 3 8% 3 13% 5 48% 19 30 Note: Percentages are calculated based on a fixed total survey response of 40 respondents. Not all respondents answered all questions. Table 53. Agency experience with cold recycling processes. Figure 42. Current use of CCPR with emulsified asphalts. Type of Recycling Less than 5 years 5 to 10 years More than 10 years We don't use this method CCPR Emulsions CO, IN, MN, MT NY, UT PA, ME AK, AL, AZ, CA, CT, FL, KS, KY, MI, MO, NC, NE, NV, OH, RI, SC, TN, VA Foamed asphalt MN GA, MD, NM, NY, VA CA AK, AL, AZ, CT, IN, FL, KS, KY, MI, MO, MT, NC, NE, NV, OH, RI CIR Emulsions IN, VA CO, DE, GA, IL, MD, MT, ND, NV, OR AZ, CA, CO, IA, ID, MN, MO, NE, NH, NM, NY, PA, SD, UT, VT, WA AK, AL, CT, FL, KS, KY, MI, OH, RI, SC, TN Foamed asphalt SC, VA, TX IL, MO, WI IA, MN, NE, NV, NY AK, AL, AZ, CA, CT, FL, IN, KS, KY, MI, MT, NC, OH, OR, RI, SD, TN, UT, VT Table 54. Individual agency responses to questions about cold recycling experience.

Figure 43. Current use of CCPR with foamed asphalt. Figure 44. Current use of CIR with emulsified asphalt. Figure 45. Current use of CIR with foamed asphalt.

92 Practice and Performance of Cold In-Place Recycling and Cold Central Plant Recycling Knowledge of, and Experience with, New CCPR and CIR Standards Question 3 asked respondents about their experience using recently released AASHTO and ARRA specifications, practices, and guidelines: “Do you have any experience with using the following cold recycling standards?” • AASHTO MP 31 Standard Specification for Materials for Cold Recycled Mixtures with Emul- sified Asphalt • AASHTO PP 86 Standard Practice for Emulsified Asphalt Content of Cold Recycled Mix- ture Designs • AASHTO PP 94 Standard Specification for Determination of Optimum Asphalt Content of Cold Recycled Mixture with Foamed Asphalt • AASHTO MP 38 Standard Specification for Mix Design of Cold Recycled Mixture with Foamed Asphalt • ARRA CR101 Construction Guide for CIR Using Bituminous Recycling Agents • ARRA CR102 Construction Guide for CCPR Using Bituminous Recycling Agents • ARRA CR201 Mix Design Guidelines for Cold Recycling Using Emulsified Asphalt Agent • ARRA CR202 Mix Design Guidelines for Cold Recycling Using Foamed (Expanded) Agent • ARRA CR301 Quality Control Sampling and Testing Guidelines for Cold Recycling Using Bituminous Recycling Agents Thirteen percent of the agencies have used the provisional AASHTO material specifications and another 13% are planning on using them for upcoming projects (Table 55). The individual agencies with experiences with the standards are shown in Table 56. Existing Standard Yes No Planning on Using Total Responses per RowPercent Responses Percent Responses Percent Responses Material Specifications AASHTO MP 31 Spec. for Cold Recycling with Emulsified Asphalt 13% 5 53% 21 13% 5 28 AASHTO MP 38 Spec. for Cold Recycling with Foamed Asphalt 5% 2 60% 24 10% 4 27 Cold Recycling with Emulsion Recycling Agent AASHTO PP 86 Emulsified Asphalt Cold Recycled Mix Design 5% 2 55% 22 15% 6 27 ARRA CR201 Mix Design for Cold Recycling Using Emulsions 15% 6 48% 19 8% 3 27 Cold Recycling with Foamed Asphalt Recycling Agent AASHTO PP 94 Foamed Asphalt Cold Recycled Mix Design 5% 2 58% 23 10% 4 26 ARRA CR202 Mix Design for Cold Recycling Using Foamed Asphalt 13% 5 53% 21 5% 2 26 Guidelines for Cold Recycling Construction Processes ARRA CR101 Construction Guidelines for CIR 13% 5 50% 20 3% 1 25 ARRA CR102 Construction Guidelines for CCPR 13% 5 48% 19 5% 2 25 ARRA 301 Quality Control Sampling and Testing Guidelines for CIR 18% 7 50% 20 3% 1 26 Note: Percentages are calculated based on a fixed total survey response of 40 respondents. Not all respondents answered all questions. Table 55. Experience with recently released AASHTO and ARRA specifications, practices, and guidelines.

Agency Survey 93   Standards Yes, we have used the standard No, we have NOT used the standard Planning on using the standard in the near future AASHTO MP 31 Standard Specification for Materials for Cold Recycled Mixtures with Emulsified Asphalt CO, DE, MT, NY, TX AK, AL, AZ, CT, GA, IN, KS, MN, MO, NC, NE, NM, NV, PA, RI, UT, VA, WA, WI MD, NM, OH, SC, TN AASHTO PP 86 Standard Practice for Emulsified Asphalt Content of Cold Recycled Mixture Designs MT, NY AK, AL, AZ, CO, CT, GA, IN, KS, MN, MO, NC, NE, NM, NV, PA, RI, UT, VA, WA, WI MD, NM, OH, SC, TN, TX AASHTO PP 94 Standard Specification for Determination of Optimum Asphalt Content of Cold Recycled Mixture with Foamed Asphalt NY, WI AK, AL, AZ, CO, CT, GA, IN, KS, MN, MO, NC, NE, NM, NV, PA, RI, UT, VA, WA, WI MD, NM, SC, TN AASHTO MP 38 Standard Specification for Mix Design of Cold Recycled Mixture with Foamed Asphalt NY, WI AK, AL, AZ, CO, CT, GA, IN, KS, MN, MO, MT, NC, NE, NM, NV, OH, PA, RI, UT, VA, WI MD, NM, SC, TN ARRA CR101 Construction Guide for CIR Using Bituminous Recycling Agents MD, MO, MT, NM, NY AK, AL, CO, CT, GA, IN, KS, MN, NC, NE, NV, OH, PA, RI, UT, VA, WA, WI AZ ARRA CR102 Construction Guide for CCPR Using Bituminous Recycling Agents MD, MO, MT, NM, NY, SC AK, AL, CO, CT, GA, IN, KS, MN, NC, NE, NV, PA, RI, UT, VA, WA, WI AZ, OH ARRA CR201 Mix Design Guidelines for Cold Recycling Using Emulsified Asphalt Agent CA, MD, MT, NM, NY, SC AK, AL, CO, CT, GA, IN, KS, MN, NC, NE, NV, PA, RI, UT, VA, WA, WI AZ, OH, TN ARRA CR202 Mix Design Guidelines for Cold Recycling Using Foamed (Expanded) Agent MD, MO, NM, NY, SC AK, AL, CO, CT, GA, IN, KS, MN, MT, NC, NE, NV, OH, PA, RI, UT, VA, WA, WI AZ, TN ARRA CR301 Quality Control Sampling and Testing Guidelines for Cold Recycling Using Bituminous Recycling Agents DE, MD, MO, MT, NM, NY, SC AK, AL, AZ, CO, CT, GA, IN, KS, MN, NC, NE, NV, PA, RI, UT, VA, WA, WI OH Table 56. Individual agency responses to experience using various standards for cold recycling. Mix designs for cold recycling using emulsion recycling agents are performed using the ARRA CR201 guidelines (15%) compared to using the AASHTO PP 86 (5%). Six agencies (15%) are planning on using AASHTO PP 86, and three agencies (8%) are planning on using ARRA CR201. A similar distribution of responses was received for cold recycling mix designs using foamed asphalt (AASHTO PP 94 and ARRA CR202). Between 13% and 15% of the agencies report using the ARRA construction guidelines; however, no more than 5% of the agencies are planning on using these guidelines in the future. A summary of comments indicates that agencies • Have developed their own standards over time and will continue to use them (8 agencies); and • Are reviewing all recent standards and guidelines, including the Wirtgen Group manual (2004), for possible adoption (2 agencies).

94 Practice and Performance of Cold In-Place Recycling and Cold Central Plant Recycling Size of Existing Cold Recycling Programs Question 4 asked respondents to “Indicate the approximate number of lane miles that are recycled per year. (Check all that apply)” Most of the cold recycling programs pave less than 50 lane-miles per year (Table 57, Table 58, Figure 46). When CIR programs pave less than 50 lane-miles per year, they use emulsion recycling agents more frequently (43%) than foamed asphalt (25%). Similar percentages of agencies use emulsions (10%) and foamed asphalt (8%) when CIR programs pave between 50 and 100 lane-miles per year. None of the responding agencies indicated that they are recycling more than 100 miles per year. This may be driven more by budgetary constraints than resistance to recycling processes. The additional comments show the following: • The number of cold recycling projects varies widely from year to year. Even if an agency uses cold recycling, it can go several years without completing a cold recycling project (4 agencies). In one case, an agency went from routinely completing 10 to 12 projects a year to no projects over 10 years. • Some agencies are just starting to use cold recycling (other than full-depth reclamation) (3 agencies). Recycling Agent and Method of Cold Recycling Less than 50 lane- miles per year 50 to 100 lane-miles per year Greater than 100 lane-miles per year Total Responses per RowPercent Responses Percent Responses Percent Responses CCPR Emulsion 38% 15 3% 1 0% 0 16 Foamed asphalt 30% 12 3% 1 0% 0 13 CIR Emulsion 43% 17 10% 4 0% 0 21 Foamed asphalt 25% 10 8% 3 0% 0 13 Note: Percentages are calculated based on a fixed total survey response of 40 respondents. Not all respondents answered all questions. Table 57. Size of existing cold recycling programs, measured in lane-miles. Type of Recycling Less than 50 lane- miles 50 to 100 lane- miles Greater than 100 lane-miles CCPR Emulsions AL, AZ, CO, KS, MN, MT, NE, NV, NY, PA, RI, SC, UT, VA IN No agencies Foamed asphalt AL, AZ, CA, KS, MD, MN, NE, NV, NY, RI, SC, VA NM No agencies CIR Emulsions AL, AZ, CO, DE, KS, MD, MN, MO, MT, NE, NM, NV, PA, RI, SC, TX, VA, WA CA, IN, NY, UT No agencies Foamed asphalt AL, AZ, KS, MN, MO, NE, NV, RI, SC, VA NY, WI No agencies Table 58. Individual agency responses on number of cold recycled lane-miles paved per year.

Agency Survey 95   Traffic Levels on Cold Recycling Projects Question 5 asked respondents to “Indicate typical annual average daily traffic (AADT) levels on your recycled pavement projects. (Check all that apply)” Agencies report using cold recycling processes on roadways with a wide range of traffic levels (Table 59, Figure 47). At lower traffic levels (less than 10,000 AADT), CIR with emulsion is the most used cold recycling process and recycling agent. Only a limited number of agencies have used cold recycling on roadways with over 25,000 AADT. The individual agency traffic levels for their cold recycled mix projects are shown in Table 60. The additional comments reveal two distinctly different approaches to project selection. The first approach is to limit cold recycling to lower AADT and lower ESAL roadways. One respon- dent noted that changing from high float emulsions to engineered emulsions may allow cold recycling on higher traffic volume roadways. The second approach to project selection is to consider only the existing pavement distresses. Key comments include these: • If there is deep cracking and a good base, CCPR is used. • The agency is phasing out a standard 0.2-ft mill and fill treatment and replacing it with a 0.3-ft CIR. Re sp on se s, % Figure 46. Size of existing cold recycling programs. Recycling Agent and Method of Cold Recycling Up to 10,000 AADT 10,000 to 25,000 AADT More than 25,000 ADT Total Responses per RowPercent Responses Percent Responses Percent Responses CCPR Emulsion 10% 4 10% 4 3% 1 9 Foamed asphalt 13% 5 10% 4 8% 3 12 CIR Emulsion 25% 10 18% 7 5% 2 21 Foamed asphalt 20% 8 13% 5 8% 3 16 Note: Percentages are calculated based on a fixed total survey response of 40 respondents. Not all respondents answered all questions. Table 59. Size of existing cold recycling programs, measured in AADT.

96 Practice and Performance of Cold In-Place Recycling and Cold Central Plant Recycling Barriers to Increased Use of Cold Recycled Processes Question 6 asked respondents to “Please indicate all barriers that limit the implementation or increased use of cold recycling methods. (Check all that apply)” Four of the choices provided for this question highlight key barriers to increased use of cold recycling processes (Table 61, Figure 48, Table 62). The two most frequently cited barriers are the lack of experience and lack of recycling contractors. Respondents noted they had slightly more experience with CIR than CCPR. The lack of project selection criteria was cited by at least 10% of the respondents. The additional comments identified other barriers: • There is a lack of funding for additional paving programs (1 agency). • High RAP hot asphalt mix is economically competitive and does not require a second contractor (1 agency). • Hot asphalt mix contractors are a strong influence on not implementing cold recycling processes (1 agency). • There are weather restrictions in the project area (2 agencies). Re sp on se s, % Up to 10,000 AADT 10,000 to 25,000 AADT More than 25,000 AADT Figure 47. Traffic levels for cold recycled projects, measured in AADT. Type of Recycling Traffic Levels Up to 10,000 AADT 10,000 to 25,000 AADT More than 25,000 AADT CCPR Emulsions CO, MN, MT, UT IN, MT, NY, PA MT Foamed asphalt CA, MD, MN, MT, VA MT, NM, NY, VA MT, VA, TX CIR Emulsions CA, CO, DE, MD, MN, MO, MT, NE, NV, WA IN, MN, MT, NM, NY, PA, VA MN, MT Foamed asphalt MN, MO, MT, NE, NV, VA, WI, TX MN, MT, NY, SC, VA MN, MT, VA Table 60. Individual agency responses on traffic levels on cold recycled mix projects.

Agency Survey 97   Barrier CCPR with Emulsion CCPR with Foamed Asphalt CIR with Emulsion CIR with Foamed Asphalt Percent Responses Percent Responses Percent Responses Percent Responses No previous agency experience 28% 11 30% 12 18% 7 25% 10 No experienced cold recycling contractors 28% 11 25% 10 25% 10 23% 9 Lack of availability of materials 3% 1 0% 0 0% 0 0% 0 Previous unsuccessful experiences 0% 0 3% 1 30% 12 5% 2 Project selection criteria not well defined 13% 5 10% 4 13% 5 13% 5 QC/QA testing not well defined* 8% 3 5% 2 10% 4 3% 1 QC/QA testing takes too long in the field* 3% 1 5% 2 3% 1 3% 1 Lack of construction specifications 13% 5 8% 3 8% 3 8% 3 Excessive time needed before opening to traffic 3% 1 5% 2 8% 3 0% 0 *QC = quality control; QA = quality assurance. Note: Percentages are calculated based on a fixed total survey response of 40 respondents. Not all respondents answered all questions. Table 61. Barriers to increased use of cold recycling processes. Figure 48. Barriers to increased use of cold recycled processes.

98 Practice and Performance of Cold In-Place Recycling and Cold Central Plant Recycling Survey Summary Agencies have the most experience with emulsion CIR. CCPR is not widely used, but when it is used, agencies with the most experience report using foamed asphalt rather than emul- sion recycling agents. Agencies that are just starting to evaluate CCPR tend to use emulsion recycling agents. Most cold recycling programs pave less than 50 lane-miles per year. While cold recycling is still used on roadways with AADTs under 10,000, these agencies are also using cold recycling on roadways with AADTs between 10,000 and 25,000. Only a limited number of agencies use cold recycling at higher traffic volumes. The most frequently cited barriers to increased use of cold recycling processes, both CCPR and CIR with either emulsion or foamed asphalt recycling agents, are the lack of agency expe- rience, lack of experienced contractors, and lack of well-defined project selection criteria. The lack of quality assurance testing and construction specifications for CCPR with foamed asphalt recycling agent was also cited as a barrier to increased use. In addition, previously unsuccessful experiences with emulsion CIR recycling agent were cited as a barrier for increased use. Most agencies have not yet used the recently released AASHTO and ARRA standards; however, several agencies are planning on using the AASHTO standards for upcoming projects. Barriers CCPR CIR Emulsion Foamed Asphalt Emulsion Foamed Asphalt No previous agency experience AK, AL, AZ, GA, MT, NC, NM, NV, OH, SC, TN AK, AL, AZ, GA, IN, MT, NC, NV, OH, SC, TN, TX AK, AL, GA, NC, OH, SC, TN AK, AL, AZ, GA, IN, MT, NC, NM, OH, TN No experienced cold recycling contractors AK, AL, AZ, GA, IN, MT, NC, NM, SC, TN, VA AK, AL, AZ, GA, MD, MT, NC, SC, TN, VA AK, AL, GA, IN, MD, MT, NC, SC, TN, VA AK, AL, AZ, GA, MT, NS, NM, PA, TN, VA Previous unsuccessful experiences --- GA AZ, DE, GA, KS, MD, MO, MT, NE, NM, NV, UT, TX NE, VA Project selection criteria not well defined AZ, GA, IN, MN, RI AZ, GA, MN, RI AZ, GA, IN, MN, PR AZ, GA, MN, RI, WI Lack of availability of materials PA --- --- --- QC/QA testing not well defined MT, OH, SC MD, MT, OH, SC AZ AZ QC/QA testing takes too long in the field GA GA, TX GA GA Lack of construction specifications GA, NM, NV, OH, SC GA, NV, SC GA, OH, SC AZ, GA, NM Excessive time needed before opening to traffic SC MD, TX DE, MD, SC --- Table 62. Individual agency responses identifying barriers.