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Suggested Citation:"Chapter Eleven - Agency Interviews." National Academies of Sciences, Engineering, and Medicine. 2013. Recycled Materials and Byproducts in Highway Applications—Summary Report, Volume 1. Washington, DC: The National Academies Press. doi: 10.17226/22552.
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Suggested Citation:"Chapter Eleven - Agency Interviews." National Academies of Sciences, Engineering, and Medicine. 2013. Recycled Materials and Byproducts in Highway Applications—Summary Report, Volume 1. Washington, DC: The National Academies Press. doi: 10.17226/22552.
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Suggested Citation:"Chapter Eleven - Agency Interviews." National Academies of Sciences, Engineering, and Medicine. 2013. Recycled Materials and Byproducts in Highway Applications—Summary Report, Volume 1. Washington, DC: The National Academies Press. doi: 10.17226/22552.
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Suggested Citation:"Chapter Eleven - Agency Interviews." National Academies of Sciences, Engineering, and Medicine. 2013. Recycled Materials and Byproducts in Highway Applications—Summary Report, Volume 1. Washington, DC: The National Academies Press. doi: 10.17226/22552.
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Suggested Citation:"Chapter Eleven - Agency Interviews." National Academies of Sciences, Engineering, and Medicine. 2013. Recycled Materials and Byproducts in Highway Applications—Summary Report, Volume 1. Washington, DC: The National Academies Press. doi: 10.17226/22552.
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Suggested Citation:"Chapter Eleven - Agency Interviews." National Academies of Sciences, Engineering, and Medicine. 2013. Recycled Materials and Byproducts in Highway Applications—Summary Report, Volume 1. Washington, DC: The National Academies Press. doi: 10.17226/22552.
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Suggested Citation:"Chapter Eleven - Agency Interviews." National Academies of Sciences, Engineering, and Medicine. 2013. Recycled Materials and Byproducts in Highway Applications—Summary Report, Volume 1. Washington, DC: The National Academies Press. doi: 10.17226/22552.
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Suggested Citation:"Chapter Eleven - Agency Interviews." National Academies of Sciences, Engineering, and Medicine. 2013. Recycled Materials and Byproducts in Highway Applications—Summary Report, Volume 1. Washington, DC: The National Academies Press. doi: 10.17226/22552.
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55 The initial survey requested that respondents identify con- tacts for projects using any of the byproducts in any of the highway applications. This request yielded 85 agency con- tacts for 92 combinations of byproducts and highway appli- cations, which were used to conduct telephone interviews using the following questions: 1. What types of byproducts were used in your project(s)? 2. Project details such as project location, date of con- struction, size, etc. (when a specific project is being evaluated, just put “standard usage” if it is commonly used in the state). 3. Was the project a success or failure? Why? 4. Did you use any specific testing of the byproducts? 5. Did you have to alter your standard QC/QA testing program when constructing the projects? 6. Were there any specific materials handling concerns with the byproducts? 7. Did the application design need to be altered for the use of the byproducts (i.e., mix designs, structural support values, etc.)? 8. Were there any construction concerns or changes needed? 9. Were there any cost savings or additional costs asso- ciated with the use of byproducts? 10. Were there any environmental issues/concerns? 11. What did your agency learn from this project? The numbers of interviews for each type of byproduct and highway application are summarized in Table 29. The following sections summarize information obtained from the interviews. The responses to questions 1 and 2 were used to sort the information based on specific byproduct and highway application. Responses to questions 3 through 10 were summarized based on the percentage of the interviews that represented the terms indicating the desirable answer. The desirable answer reflects whether “yes” or “no” would be the most beneficial for the agency. The responses to the last ques- tion are collectively summarized at the end of this section. Portland Cement ConCrete aPPliCations A total of 25 interviews were conducted to evaluate agency experiences with byproducts in PCC applications. Eighteen interviews covered coal combustion byproducts with five interviews addressing the use of Type C or F, seven the use of only Type F, and six only the use of Type C. Five agen- cies were interviewed regarding the use of slag; all five used only GGBFS. Seven interviews were conducted for agencies using slags in PCC applications. One agency had experience with blast fur- nace slag (no specified type), five agencies specified GGBFS, and one agency used steel slag. Table 30 summarizes the responses to questions 3 through 10 for using coal combustion byproducts in PCC applications. Coal Combustion Byproducts in Portland Cement Concrete applications Most of the interviews indicated that agencies believed they did not need to change their project details, the use of the byproduct was saving money, and the application performance was good. The two major downsides to using byproducts were the need to adjust QA/QA programs and construction processes. Only one state noted a lack of success, which was the result of the difficulty in finishing the PCC surface. Three other agencies indicated similar problems, but still consid- ered their projects as successful. None of the states needed to alter their typical project design details when using the byproducts in the applications. Typical testing associated with the byproducts evaluated the chemical and physical properties of the cement, mortar, or concrete properties rather than the properties of the byproducts themselves. Agencies address byproduct properties by using existing AASHTO or ASTM standards for the properties of Type C and Type F fly ashes. Although it was not clear from the interview notes, it is likely those states using a chemical evaluation are evalu- ating the individual components (e.g., portland cement and coal combustion byproduct). In most cases, standard QC/ QA programs were sufficient. In one case, the contractor was required to provide material certifications as a QC/QA measure. The only handling comments noted in the interviews were dust control and inhalation concerns and the need for extra silos for storage at the plant. Design changes commonly needed when using coal combustion byproducts focused on adjustments to the mix design composition (e.g., volumet- rics, water reducers, and air entrainment). Idaho required an independent assurance testing laboratory. Five states indi- cated construction concerns were related to delays in the set chapter eleven agenCy interviews

56 Material Applications PCC HMA Aggregate, Embankment, and Fill Coal Combustion Byproducts Fly Ash (general) 5 0 0 Fly Ash, Type C 6 0 0 Fly Ash, Type F 7 0 0 Bottom Ash 0 0 1 Ponded Ash 0 0 1 Total 18 0 2 Slags BFS 1 1 1 GGBFS 5 2 3 Boiler Slag 0 0 0 Steel Slag 1 3 1 Copper Slag 0 0 1 Total 7 6 6 Mineral and Quarry Byproducts Baghouse Fines 0 2 0 Pond Fines 0 1 0 Screenings 0 1 0 Copper, Silver, and/or Gold Tailings 0 1 0 Total 0 5 0 Tire Byproducts Shredded Tires 0 1 2 Terminal Blend (wet process) 0 2 0 Crumb Rubber (wet process) 0 7 0 Chipped Tires 0 0 1 Total 0 10 3 Miscellaneous Byproducts Cement Kiln Dust 0 2 0 Shingles—Manufacture 0 5 0 Shingles—Tear Offs 0 4 0 Recycled PCC and HMA Byproducts RCA 0 0 8 RAP 0 14 0 TABlE 29 SuMMARy OF NuMBER OF STATES WITH ExPERIENCE uSING ByPRODuCTS IN HIGHWAy APPlICATIONS Question Assumed Desirable Response Percent of Agencies Interviewed with Response Coal Combustion Byproducts Slag Cost Savings? Yes 86 60 Success? Yes 93 100 Project Details Altered?1 No 100 100 Standard QC/QA Altered? No 57 100 Handling Concerns? No 93 80 Design Altered?2 No 71 100 Construction Changes? No 50 60 Environmental Concerns? No 93 100 No. of Interviews 18 7 1Project details refer to project location, size, type, etc. 2Design refers to mix design, structural design, etc. TABlE 30 INTERvIEW SuMMARy OF ByPRODuCTS IN PCC APPlICATIONS

57 • Slag byproducts (six interviews) • Mineral and/or quarry byproducts (five interviews) • Scrap tire byproducts (ten interviews) • Shingle byproducts (nine interviews) • RAP byproduct (14 interviews). Table 31 summarizes the responses to questions 3 through 10 for byproducts used in HMA applications. The slag byprod- ucts used were steel slag (three interviews), GGBFS (two interviews), and boiler slag (one interview). The main min- eral and/or quarry byproducts used in HMA applications were fine mineral or quarry byproducts (five interviews). Fourteen interviews were conducted to capture agency experiences using RAP. Ten interviews were conducted to evaluate state experiences with scrap tire rubber in HMA using either the dry process (aggregate replacement) or an asphalt cement modifier (wet process). Only two interviews covered agency experience with using CKD in HMA as mineral filler. Nine respondents answered questions concerning the use of shin- gles in HMA; four of the nine indicated they allowed either the use of manufactured or tear-offs. slag Byproducts in Hot mix asphalt applications Five interviews were conducted with states using slag byprod- ucts in HMA applications (see Table 31). Only about 57% of the agencies managed to place successful projects and only 29% believed there was an economic advantage to using slag in HMA applications. The majority (>50%) of the responses showed that changes were made to materials handling, designs, and construction processes. less than 30% of the agencies changed QC/QA programs. The steel slag byproduct had a high specific gravity and was the main point to consider in the necessary mix design changes. Increases in field sample sizes for additional testing were the most often noted changes. Construction processes needed changes in application rates when specifications were based on the weight of materials for a given area. Some agen- cies noted the difficulty in controlling the mix temperatures time and difficulty in finishing the PCC surface. All of the respondents indicated a cost savings was achieved; however, several agencies noted that the savings may depend on the contractor. In one case, the cost savings were attributed to a lower life-cycle cost rather than an initial cost savings. Three states listed leachate testing as an additional consideration for projects when using these byproducts. One state noted that using silica fume along with the GGBFS generated inha- lation concerns (i.e., microsilica). The positive lessons learned when using coal combus- tion byproducts included low permeability (i.e., protection of reinforcing steel from corrosion) and good ASR resis- tance. Disadvantages include difficulty in finishing, delays in finishing times, slow initial strength gains, and material variability. slag Byproducts in Portland Cement Concrete applications None of the agencies had a need to change project details, designs, or QC/QA programs, and none indicated concerns with environmental issues. Standard project details, testing, and QC/QA programs were used to produce consistently suc- cessful projects. Handling considerations included the need for extra silo storage capacity and cold weather concreting concerns owing to the reduced heat of hydration of the PCC. Slow set times resulted in construction delays and finish- ing issues. Three of the five states with experience in using GGBFS indicated a cost saving, whereas two states reported no change in the PCC application costs. Advantages included ASR and sulfate attack mitigation, and that a denser, less per- meable concrete was achieved. Hot mix asPHalt aPPliCations A total of 44 interviews were conducted covering agency use of byproducts in asphalt cement and asphalt cement concrete applications. Interviews were conducted for: Question Assume Desirable Response Percent of Agencies Interviewed with Response Slag Mineral/Quarry Tires Shingles RAP Successful? Yes 57 100 603 80 100 Cost Savings? Yes 29 100 20 80 86 Project Details Altered?1 No 57 100 40 20 93 Standard QC/QA Used? Yes 71 75 60 80 100 Handling Concerns? No 43 75 60 20 57 Design Altered?2 No 43 100 10 40 43 Construction Changes? No 14 75 50 80 64 Environmental Concerns? No 71 75 50 40 79 No. of Interviews 6 5 10 9 14 1Project details refer to project location, size, type, etc. 2Design refers to mix design, structural design, etc. 3Successes when using tires in HMA are limited to only the wet process; dry process was considered unsuccessful by interviewees. TABlE 31 INTERvIEW SuMMARy OF ByPRODuCTS IN HMA APPlICATIONS

58 slower production rates (Nebraska) or contractor familiarity with using RAP (Missouri). About 57% of the agencies noted that conventional han- dling methods were applicable to handling RAP. When there were concerns, they were related to achieving aggregate specification values when post-processing the RAP (i.e., fractionating the RAP into a number of sizes). The only performance considerations were related to rough longitudinal joints (New Jersey) and a higher cracking poten- tial (New Mexico) owing to embrittlement of the binder by the old RAP asphalt cement. The interviews revealed a number of lessons learned when using RAP in HMA applications. There appeared to be less difficulty in using RAP when the percentages are lower (about 15% RAP); however, several states were working on how to increase the allowable percentage of RAP. Both the grada- tion and binder quantities of the application product needed to be closely monitored. limited use of RAP was based on the anticipated depletion of RAP availability and competing byproducts (e.g., RAP vs. tire rubber). Cost considerations dis- cussed were how to credit the contractor for asphalt content in the RAP (New Mexico), which now credits 50% of the RAP binder instead of 100%. virginia noted cost savings were tied to the handling and processing of the RAP prior to use in HMA. scrap tire Byproducts in Hot mix asphalt applications Ten interviews were conducted with agencies using scrap tires in HMA applications. Nine interviews were with agen- cies using the wet process of modifying asphalt with crumb rubber. Of these nine agencies, seven used the traditional field blend method for adding the crumb rubber to the asphalt. The two other agencies used the crumb rubber in terminal blends, which is a newer method of modifying the asphalt at the terminal rather than at the HMA contractor’s plant. About 60% of the agencies had successful projects. Two states that reported unsuccessful projects (Alaska and Washington) had used scrap tire byproducts with the dry process that considers the rubber as an aggregate replacement. These projects had premature performance-based failures. Georgia and Texas routinely used crumb rubber in the wet process, whereas most of the other states interviewed indicated they were at various stages of and are approaching routine use. Only 20% of the agencies reported that this byproduct reduced the cost of the projects. Georgia, New Hampshire, and Texas indicated that cost savings were the result of increased performance (i.e., better life-cycle costs). The most frequently cited handling limitation was the avail- ability of the equipment for HMA plant blending operations. This method of modifying the asphalt usually needed to move equipment. Adjustments were needed for mix design meth- ods as well as the assessments of mix properties. Construction and moisture content in the field samples. Additional costs were associated with using steel slag in HMA because the high specific gravity increased the haul costs for a given vol- ume of mix. Colorado, Florida, and virginia reported they would not use this combination of byproduct and HMA again because of construction problems and costs. Iowa was the only state that indicated a routine use of steel slag as a high-quality friction course. mineral and Quarry Byproducts in Hot mix asphalt applications Five interviews were conducted with states using mineral or quarry byproducts in HMA applications. All five agencies said the projects were successful and resulted in cost savings. None of the states needed to alter their project details, mix designs, and/or structural designs. Only one of four responses indicated a need to change QC/QA programs, construction processes, or had environmental concerns. Texas tests for wear when using copper, silver, and/or gold tailings and, depending on the fineness of the material, needed to require that the rolling patterns be adjusted by monitor- ing in-place density with a nuclear gauge. When using the copper, silver, and/or gold tailings, Texas noted training of the field crews was essential so that the staff was aware of any testing issues. Dust, an environmental concern, was asso- ciated with using baghouse fines and on general handling concerns associated with using the tailings. lessons learned focus on the need for evaluating and analyzing the perfor- mance of the application products and the need for outreach education and technology transfer for local agencies and maintenance departments. recycled asphalt Pavements in Hot mix asphalt applications Fourteen interviews were conducted for agencies using RAP in fresh HMA (see Table 31). This survey was limited to cen- tral plant RAP use as there is a separate synthesis for in-place asphalt pavement recycling. All (100%) of the 14 interviews showed agencies considered their RAP projects successful; however, only 86% of the agencies noted a corresponding cost savings. Project details only needed to be altered by 7% of the agencies. A number of states reported that they focused on changes in the mix designs that were related to adjustments of the quantities of binder in the final mix. Most of the laboratory testing change involved evaluating the asphalt content and gradation of the RAP, extraction and recovery of RAP binder, and addressing determination of PG specification grading of binders. Although the extent of the laboratory testing increased, none of the interviews mentioned a need to adjust their QC/QA programs. Standard construction processes were used by 64% of the agencies. When changes were needed, they were related to

59 ucts should be based on performance and not legislatively driven. Environmentally related comments included a concern with potential health problems from small particle sizes of the roofing byproduct components and the need to keep the shingles away from the flames in the HMA drum (i.e., smok- ing). All of the four states using tear-offs (a byproduct of construction debris) indicated environmental concerns with the possibility of asbestos in the shingle supply. UnBoUnd HigHway aPPliCations Sixteen interviews were conducted with agencies with expe- rience with byproducts used in various unbound applications (Table 32): • Coal combustion byproducts (two interviews) • Slag byproducts (six interviews) • Tire byproducts (three interviews) • CKD (two interviews) • Reclaimed concrete aggregates (eight interviews). The only use of coal combustion byproducts in an unbound highway application was bottom and ponded ash (Missouri). Six interviews were conducted with agencies using slag and three for the use of shredded tires. Of the six states with expe- rience using slags in unbound applications, one used BFS, three used GGBFS, and two agencies had experience using non-ferrous slag. The most frequent contact information was provided for unbound applications using RCA. Coal Combustion Byproducts in Unbound applications Only Missouri uses coal combustion byproducts in embank- ments. The pilot projects were classified as successes using observations noted slower production rates and compaction difficulties with the crumb rubber modified asphalts. Smok- ing when using crumb rubber was noted as an environmental consideration. lessons learned focused on the need to collect performance data. roofing shingles in Hot mix asphalt applications Interviews revealed that five states (Delaware, Iowa, Missouri, Texas, and virginia) were using roofing shingle manufactur- ing byproducts in HMA applications and four of these states were also using tear-offs. Only Texas indicated the use of shin- gles in HMA applications was close to becoming a standard. About 80% of the interviews indicated successful projects were placed, cost savings were noticed, standard QC/QA programs were used, and conventional construction processes were appli- cable. At the same time, 80% of the interviews showed agen- cies needed to alter project designs and/or materials handling procedures. Approximately 60% of the agencies expressed environmental concerns (related to asbestos) and/or the need to change mix designs. Mix designs needed to consider volu- metrics, binder content, additional fiber content, and in-place binder. HMA testing adjustments included chemical testing of the byproduct, checks for deleterious materials (e.g., asbestos), recovered binder properties, and performance testing. Handling difficulties were related to the clumping or ball- ing of the ground shingles. Delaware reported mixing the shingles with RAP to minimize the problems with balling of the shingles, and Iowa noted that modifications were needed to the plant feeder system when adding the shingles. Mis- souri contractors were using a finer grind of the shingles to minimize plant feeding problems. The responses showed that the use of shingles was con- sidered a viable use of the byproduct once the handling concerns are overcome. Texas noted that the use of byprod- Question Response Percent of Agencies Interviewed with Response Coal Combustion Slag Tires CKD RCA Cost Savings? Yes 100 33 50 100 78 Success? Yes 100 67 100 0 89 Project Details Altered?1 No 100 67 50 50 100 Standard QC/QA Used? Yes 0 100 100 100 78 Handling Concerns? No 0 100 0 100 56 Design Altered?2 No 100 33 50 100 89 Construction Changes? No 100 100 100 100 56 Environmental Concerns? No 100 67 0 100 89 No. of Interviews 2 6 3 2 8 1Project details refer to project location, size, type, etc. 2Design refers to mix design, structural design, etc. RCA = recycled concrete aggregates; CKD = cement kiln dust. TABlE 32 INTERvIEW SuMMARy OF ByPRODuCTS IN uNBOuND APPlICATIONS

60 recycled Concrete aggregates Byproducts in Unbound applications Nine states used RCA as an aggregate replacement in base applications (see Table 32). Most states (89%) indicated cost savings, and 78% of the agencies reported successful proj- ects. Maryland indicated they tried this byproduct in 1977 but only had “just OK” success. Colorado, Delaware, Iowa, Mississippi, Nebraska, Missouri, Texas, and virginia suc- cessfully use RCA and Mississippi is in the process of devel- oping standard specifications for this byproduct. A few of the respondents indicated that their QC/QA pro- grams (22%) and construction processes (44%) needed some changes. QC/QA changes were usually a need for additional testing. The most important property to measure was iden- tified as gradation. In-place density testing was difficult to measure for at least one agency (Maryland). The major dif- ficulty was the inability to use a standard sand cone density test resulting from large void spaces. Nebraska used density testing based on establishing rolling patterns for each project. Mix design changes were occasionally needed when using partial sand along with the RCM in the application. The liq- uid limit requirements needed to be adjusted or waived in the specification requirements. Comments related to handling focused on accounting for, or adjusting, moisture content, monitoring for gradation consistency, stockpile building prac- tices, and room for the additional stockpiles of materials. virginia noted that the stockpiles moisture content was sta- bilized by watering the stockpile. Workability was related to fines and moisture content with higher contents resulted in reduced workability. Mississippi occasionally had compac- tion concerns that were thought to be related to cold, wet weather. lessons learned comments were very positive. One comment was “would use more if it were available.” lessons learned This section presents a summary of the lessons learned by the agencies using byproducts in highway applications. In general, the advantages associated with using byproducts in highway applications are (Table 33): • Byproducts usually provided better material properties than the natural material it replaces. • Agency staff perceived a cost reduction was obtained when using the byproduct. • Agency staff considered it a good use of a recycled by- product. • Performance characteristics such as alkali–silica reac- tivity, sulfate resistance, and reduced permeability needed to be addressed in the mix design phase. • Improved pavement surface characteristics included better friction and lower vehicle–pavement noise. • Generally better durability and performance of the high- way application product was achieved. • longer service life of the application was achieved. standard density testing for quality control. The only han- dling comments were that fugitive dust (also an environ- mental concern) needed to be controlled and the moisture content in the ponded ash be considered when mixing for soil remediation. slag Byproducts in Unbound applications Two states have used BFS in unbound highway applications (utah and New york). Neither utah nor New york needed to alter their project details to achieve successful projects with their standard QC/QA programs. utah indicated both higher costs and material chemistry concerns with sulfate and chlo- ride in the BFS byproducts. New york noted improved dura- bility and a longer life span (i.e., lower life-cycle cost) were achieved when using BFS, and utah noted the desire to pro- mote further use of BFS. Illinois indicated previous experi- ence using copper slag as an aggregate, but the project was not successful. The respondent was not sure of the reason(s) for the failure. scrap tire Byproducts in Unbound applications New york, New Jersey, and virginia were interviewed on their use of shredded or chipped tires in unbound applica- tions such as embankments and backfill (see Table 32). Both New york and virginia noted they originally placed embank- ments as a result of agency emphasis in the 1990s, but with- out dedicated funding incentives to use the material, little byproduct is currently being used. Both states indicated an increased need to conduct ground-water testing for unde- sirable leachates. Construction concerns were related to compaction and density. Safety concerns were related to worker safety when han- dling the shredded steel belted tires (without the steel fibers being removed) and clumping of the tire shreds. The cost could be defrayed by either free tires or state funding support for disposal. The general consensus was that the byproduct could be used in this application, but it is not yet cost-effective without funding incentives. Cement Kiln dust in Unbound applications Both agencies interviewed (Missouri and Texas) have used cement kiln dust (CKD), although neither indicated the use resulted in a cost savings. Testing adjustments included evalu- ating the support of the application for stabilized base with cone penetrometer testing and leachate testing for both stock- piled CKD and after use in applications. Neither state reported any handling concerns, alterations to designs, or construction concerns. Texas noted that CKD cost about half as much as using lime and fly ash, and also noted the performance of the application product was good but the politics could influence the availability of the byproduct.

61 Application Byproduct Category Type of Byproduct State B et te r th an N at ur al M at er ia l C os t- E ff ec tiv e G oo d U se o f R ec yc le d B yp ro du ct Im pr ov ed W or ka bi lit y A SR R es is ta nc e D ur ab ili ty a nd /o r Pe rf or m an ce St re ng th Su lf at e R es is ta nc e Fr ic tio n R ed uc ed Pe rm ea bi lit y N oi se R ed uc tio n L on ge r A pp lic at io n L if e BASE (unbound material) Coal combustion Bottom & ponded ash MO X RCA RCM CO X X X DE X IA X MD X NE X MO X VA X X Slag BFS slag NY X X X UT X Tires Shredded NY X VA HMA Manufacturing and construction CKD MO X TX X X Shingles, man. DE X Shingles, man., & tear-offs MO X Mineral and quarry Baghouse TX X RAP RAP DE X ID X NE X Slag Steel IA X Boiler MO X GGBFS VA X X X Tires Dry MO X Wet NY X NH X NJ X X NY X TX X PCC Fly ash General AR X FL X X X NV X NY X X X F ID X VA X X C,F MS X X NJ X X X Slag GGBFS AK X DC X DE X MS X X NJ X Man. = manufactured; C = Type C fly ash; F = Type F fly ash. TABlE 33 SuMMARy OF lESSONS lEARNED ABOuT THE ADvANTAGES TO uSING ByPRODuCTS IN HIGHWAy APPlICATIONS • Construction difficulties • Poor experiences • lack of byproduct material properties • Costs • Needed mix design changes • local availability of byproduct • Environmental concerns • Numerous or conflicting environmental regulations • lack of training for agency and contractor field staff. Table 34 summarizes the lessons learned about barriers that need to be overcome to improve and advance the use of byproducts in highway applications. It can be noted that the initial agency written survey that requested agency contacts for the phone interviews yielded contacts for byproducts in primarily main stream usage and with a history of successful projects. In general, the barriers were: • lack of experience with the byproduct in a particular application

62 Application Byproduct Category Type of Byproduct State N ot C os t- E ff ec tiv e C lo gg ed D ra in ag e Sy st em s C on st ru ct io n D if fi cu lti es L ac k of A va ila bi lit y Po or E xp er ie nc e B yp ro du ct M at er ia l P ro pe rt ie s C lim at e L im ita tio ns L ac k of E xp er ie nc e M ix D es ig n A dj us tm en ts A dd iti on al T ra in in g N ee de d fo r In sp ec to rs a nd F ie ld S ta ff C on ta m in at es in B yp ro du ct R eg ul at io ns a nd P ol iti cs N ee d to R es tr ic t S ou rc e of B yp ro du ct E nv ir on m en ta l C on ce rn s BASE (unbound material) RCA — VA X MS X TX X Slag Copper slag IL X Tires Shredded NY X X VA HMA Manufacturing and construction Shingles, man., & tear-offs IA X TX X VA X Mineral and Quarry Baghouse CO X Copper, silver, & gold tailings TX Pond finds & screenings GA X RAP — ID X CO X GA IA MS MO X NM X NJ NY TX X VA X X WA X HMA Slag BFS FL X GGBFS IA Steel IA X IA X CO X VA X X Tires Dry AK X X WA X X Shredded tires DE X NV X Terminal, wet NY X Wet NY X NY X X CO X GA X VA X PCC Fly ash C NE X C, F CO ND X TX X F ID General NV DE X WA X Man. = manufactured; C = Type C fly ash; F = Type F fly ash. TABlE 34 SuMMARy OF lESSONS lEARNED ABOuT THE DISADvANTAGES TO uSING ByPRODuCTS IN HIGHWAy APPlICATIONS

Next: Chapter Twelve - Conclusions and Recommendations »
Recycled Materials and Byproducts in Highway Applications—Summary Report, Volume 1 Get This Book
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TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 435: Recycled Materials and Byproducts in Highway Applications—Summary Report, Volume 1 summarizes the results of a project that describes the experiences of transportation agencies in determining the relevant properties of recycled materials and industrial byproducts and the beneficial use for highway applications.

NCHRP Synthesis 435 is presented in eight volumes and is designed to help serve as a guide to states revising the provisions of their materials specifications to incorporate the use of recycled materials and industrial byproducts.

Volume 1 is available in print and electronic versions. Volumes 2 to 8 are in electronic format only. The eight volumes are:

Volume 1 Recycled Materials and Byproducts in Highway Applications—Summary Report

Volume 2 Coal Combustion Byproducts

Volume 3 Non-Coal Combustion Byproducts

Volume 4 Mineral and Quarry Byproducts

Volume 5 Slag Byproducts

Volume 6 Reclaimed Asphalt Pavement, Recycled Concrete Aggregate, and Construction Demolition Waste

Volume 7 Scrap Tire Byproducts

Volume 8 Manufacturing and Construction Byproducts

A NCHRP Synthesis 435 website with links to all 8 volumes is available.

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