Effects of Scrap Tire Rubber on Properties of Hot-Mix Asphaltic Concrete - A Laboratory Investigation. By: Tarun R. Naik, and Shiw S.

Transcription

1 Center for By-Products Utilization Effects of Scrap Tire Rubber on Properties of Hot-Mix Asphaltic Concrete - A Laboratory Investigation By: Tarun R. Naik, and Shiw S. Singh Report No. 236 November 1994 Department of Civil Engineering and Mechanics College of Engineering and Applied Science THE UNIVERSITY OF WISCONSIN - MILWAUKEE -1

2 EFFECTS OF SCRAP TIRE RUBBER ON PROPERTIES OF HOT-MIX ASPHALTIC CONCRETE- A LABORATORY INVESTIGATION Prepared for Paul J. Koziar, Director Waste Tire Removal and Recovery Program Wisconsin Department of Natural Resources Bureau of Solid and Hazardous Waste Management 101 S. Webster Street P.O. Box 7921 Madison, WI BY: Tarun R. Naik, Director and Shiw S. Singh, Post Doctoral Fellow Center for By-Products Utilization Department of Civil Engineering and Mechanics College of Engineering and Applied Science The University of Wisconsin-Milwaukee P.O. Box 784 Milwaukee, WI Telephone: (414) Fax: (414)

3 TABLE OF CONTENTS ABSTRACT ii ACKNOWLEDGEMENTS iii 1. INTRODUCTION EXPERIMENTAL PROGRAMS GENERAL MATERIEALS Aggregates Asphalt Binder Crumb Rubber Modifier (CRM) MIXTURE DESIGNS RESULTS and DISCUSION EFFECTS OF ASPHALT EFFECT OF INCLUSION OF CRM SUMMARY AND CONCLUSIONS REFERENCES i

4 ABSTRACT The major aim of this investigation was to establish mixture proportion technology for manufacture of paving materials containing scrap tire rubber using a dry process, especially a generic system. This research focussed toward development of a modified generic technology that would not require any changes in gradation of Crumb Rubber Modifier (CRM) in manufacture of dense-grade asphaltic concretes (DGACs) varying in aggregate gradations. The new system will contain a fixed size or a combination of sizes of CRM for all DGACs. It is believed that this new technology will have much greater acceptance than the standard generic technology in commercial application due to its simplicity without compromising performance. An experimental investigation was carried out to evaluate the influence of the size of CRM on performance of asphaltic paving materials. Two different Wisconsin DOT dense-graded asphaltic concrete mixtures were selected as reference mixtures for this investigation. Two sizes of CRM (3 mm and 180 µm) were chosen, to represent the upper and lower limits of CRM size, based on technical and economic considerations. The coarse CRM (3 mm) was varied between 1 and 9% of total asphalt cement used, and the fine CRM (180 µm) was varied between 5 and 15% of total asphalt used with an increment of 2%. For each asphaltic mixture, properties such as air voids, voids in the mineral aggregates (VMA), voids filled with asphalt cement (VFA), theoretical maximum specific gravity, bulk specific gravity, stability, and flow were determined. Based on the ii

5 analysis of data collected, it was found that addition of the coarse CRM (3 mm) affected the performance of both Wisconsin DOT mixtures adversely. Thus, this size of CRM is concluded to be unsuitable for manufacture of rubberized paving materials. However, the materials made with the fine CRM (180 µm) showed the most encouraging performance up to 15% CRM addition. The materials made with 180 µm can be commercially utilized without any changes in conventional mixture design and production technology. However, in order to achieve better economics, a combination of sizes need to be further investigated. Additionally, further investigations are needed to establish field performance of the mixtures that were developed in this laboratory investigation at the Center for By-Products Utilization, University of Wisconsin-Milwaukee. iii

6 ACKNOWLEDGEMENTS The authors express their appreciation to Wisconsin Department of Natural Resources for providing financial support for this project. Special appreciation is expressed to Mr. Paul J. Koziar for his valuable suggestions and help during the startup phase of this investigation. The authors would like to express their deep sense of gratitude to Mr. David F. Nelson, President, WISE, Milwaukee, WI, whose valuable help and encouragement were instrumental in establishing the scrap tire use research project at the Center for By-Products Utilization, UW-Milwaukee. The authors would also like to express appreciation to Mr. James C. Kaminski, Commissioner of Public Works, City of Milwaukee, for his encouragement and support for investigation. Special appreciation is expressed to Mr. Robert A. Huelsman, Environmental Engineer, Department of the Force, Milwaukee, for his valuable support, commitments, and interest in the project. Thanks are due to Payne and Dolan, Inc. for providing facilities for making and testing of asphaltic concrete mixture for this investigation. The authors express their deep sense of gratitude to Mr. Jack Weigel of Payne and Dolan, Inc. for his active help, participation, and suggestion throughout the study. The authors express sincere thanks to Ms. Amanda Como for her help in data collection. A note of thanks are due to Mr. M. M. Hossain for preparation of iv

7 illustrations used in this report. The primary sponsors of the Center for By-Products Utilization are: Dairyland Power Cooperative, LaCrosse, WI; Madison Gas and Electric Company, Madison, WI; National Minerals Corporation, St. Paul, MN; Northern States Power Company, Eau Claire, WI; Wisconsin Electric Power Company, Milwaukee, WI; Wisconsin Power and Light Company, Madison, WI; and Wisconsin Public Service Corporation, Green Bay, WI. Their continuing help and interest in the activities of CBU is gratefully acknowledged. v

8 SECTION 1 INTRODUCTION Recent technical and economic feasibility investigations carried out at the Center for By-Products Utilization revealed that there is a very high potential for large scale use of scrap tires in manufacture of rubberized asphaltic pavements and other construction materials. Tire rubber is ground to particulate form prior to it's utilization as an ingredient for such materials for improving their properties with compared to materials without crumb rubber from used tires. The used tire particulates are called Crumb Rubber Modifier (CRM). When added to asphalt mixtures, they tend to modify properties of the asphaltic materials. Two different processes exist for introducing CRM in paving materials. They are wet and dry processes. In the case of wet processes, 15-25% of CRM is reacted with asphalt at elevated temperature ( F) to produce a new binder which is thicker and more elastic compared to conventional asphalt. The new binder is used in the same manner as that of conventional asphalt in manufacture of paving and other asphaltic materials. Two different processes that use the wet processes are the McDonald (batch) and the continuous blending technologies. The McDonald technology involves blending of CRM with asphalt in a holding tank and then allowing sufficient time for reactions between them in the tank. In the continuous blending technology, asphalt and CRM are mixed prior to mixing the blend with the asphaltic mixture. The continuous system uses finer CRM compared to the McDonald -1

9 technology. The detailed description of these technologies is presented in the accompanying report (1) and elsewhere (2-5). In the dry process, CRM is blended with aggregates prior to introduction of asphalt to the mixture. The resulting material is generally referred to as rubber filled systems. Two different systems, namely, Plus Ride and generic technologies are commonly used to manufacture rubber filled systems. The PlusRide system is a patented technology which was originally developed in the late 1960's in Sweden and was patented under the trade name "Rubit". Currently, EnvirOtire, Inc. markets this technology as PlusRide II in the USA. The advantages of the PlusRide system include increased flexibility, fatigue life, resistance to reflective, shrinkage and thermal cracking, and resistance to rutting compared to conventional asphaltic paving. The generic systems was developed by Takallou in 1986 (6). This system employs designs and standards similar to that for conventional asphaltic concrete (1, 2, 3, 6, 7). The gradation of CRM is designed to be compatible with a specific dense-graded aggregate. These generic systems have been used in several states including New York, Oregon, and Ontario with a considerable success. In general, the materials produced from the wet processes is costlier than the rubber filled materials produced by the dry processes. Of the two rubber filled systems, namely the PlusRide and the generic system, the latter is the most cost-effective. Because of low cost and minimum changes in the design of conventional asphalt concrete systems, the generic system has a great potential for -2

10 widespread application in paving work. However, there is limited published data available on the performance of the generic system. This investigation was under taken to develop an improved design of the generic technology for increasing its acceptance in commercial applications in Wisconsin. The major aim of the work reported herein is to establish an optimum mixture proportion for the generic system without much change in mixture proportioning and manufacturing of conventional materials. This report includes experimental data on the effects of fineness of CRM on performance of two different Wisconsin DOT mixtures by using a modified generic technology. In the original generic system, CRM gradation is adjusted in order to be compatible with individual gradation of aggregates used in dense-graded asphaltic concrete (DGAC) systems. Whereas, in the modified generic systems that is being reported in this work, it was planned to keep the same size or gradation of CRM for all DGACs. This will allow a greater acceptance of CRM in asphaltic pavements in Wisconsin because mixture designers do not have to redesign gradation of CRM as required by individual aggregate gradations of different DGACs. -3

11 SECTION 2 EXPERIMENTAL PROGRAMS 2.1 GENERAL In order to evaluate the effects of CRM in asphaltic paving materials, two different asphaltic mixtures established by Wisconsin DOT were selected for this work as reference mixtures. These were MV-3 and MV-4 dense-graded asphaltic mixtures for medium volume traffic conditions. This work involved establishing a modified generic system using a fixed size or fixed gradation of CRM as opposed to the gradation of CRM used in the standard generic system. For the present investigation two different sizes of CRM were selected: 3 mm and 180 µm. The entire experimental work was divided into two different series. The first series of experiments were concerned with evaluation of the effects of 3 mm CRM and the second series of investigation was related to the effect of inclusion of 180 µm CRM on performance of asphaltic concrete systems. The amount of CRM was varied between 1 and 9% by weight of asphalt cement (used for the control mixture) for the coarse CRM, and 5 and 15% for the fine CRM. 2.2 MATERIALS All materials used in this investigation except CRM were supplied by Payne and Dolan, Inc. All materials were tested using the R and D Laboratory facilities available -1

12 at Payne and Dolan, Inc Aggregates Sieve analysis was carried out to determine gradation of the fine and coarse aggregates. A "dry" sieve analysis was conducted in accordance with ASTM C 136 (AASHTO T 27). The amount of materials finer than 75 µm (No. 200) sieve in aggregate was measured per ASTM C 117. The bulk and apparent specific gravity of coarse and fine aggregates were determined by ASTM C 127 (AASHTO T 85) and C 128 (AASHTO T 84), respectively. The effective specific gravity was computed from theoretical maximum specific gravity using ASTM D Los Angeles abrasion resistance, the resistance to degradation of coarse aggregate, was evaluated in accordance with ASTM C 131. Sulfate soundness of the aggregates was measured in accordance with ASTM C 88. and 2-2. The properties of aggregates are shown in Tables 2-1 and 2-2, and in Fig Asphalt Binder The asphalt cement used was Type It was obtained from AMOCO. It's specific gravity at 77 F was

13 TABLE 2-1: Properties of Aggregates Used in Mix MV-3 Aggregate Source Sample No. Test Number Material Source Location A-92 ½" Chip East Quarry SE ¼ SEC 26 T7 RN 19E WAUK. CO A-92 ¼" Chip East Quarry SE ¼ SEC 26 T7 RN 19E WAUK. CO A-92 ¼" Screenings East Quarry SE ¼ SEC 26 T7 RN 19E WAUK. CO A-92 Manufactured Sand East Quarry SE ¼ SEC 26 T7 RN 19E WAUK. CO A-92 Washed Sand Johnson - S.& J. NW ¼ SEC 6 T5 RN 20E WAUK. CO A-92 BLD 10.0% 1233-A-92 BLD 15.0% Aggregate Gradation (% Passing) 1218-A-92 BLD 30.0% 1208-A-92 BLD 30.0% 1220-A-92 BLD 15.0% Blend Job Mix Spec. 1.0 IN ¾ IN ½ IN /8 IN # # # # # # # Agg. Sp. Gr Effective Agg.Sp.Gr = 2.78 Elongated Particles = <5% Soundness = 2.5 L.A. Wear = 4.1 (100) 21.0(500) -3

14 TABLE 2-2: Properties of Aggregates Used in Mix MV-4 Aggregate Source Sample No. Test Number Material Source Location A-92 3/8" Chip East Quarry SE ¼ SEC 26 T7 RN 19E WAUK. CO A-92 ¼" Chip East Quarry SE ¼ SEC 26 T7 RN 19E WAUK. CO A-92 ¼" Screenings East Quarry SE ¼ SEC 26 T7 RN 19E WAUK. CO A-92 Manufactured Sand East Quarry SE ¼ SEC 26 T7 RN 19E WAUK. CO A-92 Washed Sand Johnson - S.&J. NW ¼ SEC 6 T5 RN 20E WAUK. CO A-92 BLD 10.0% 1233-A-92 BLD 10.0% Aggregate Gradation (% Passing) 1218-A-92 BLD 30.0% 1208-A-92 BLD 30.0% 1220-A-92 BLD 20.0% Blend Job Mix Spec. 1.0 IN ¾ IN ½ IN /8 IN # # # # # # # Agg. Sp. Gr Effective Agg.Sp.Gr = 2.78 Elongated Particles = <5% Soundness = 2.5 L.A. Wear = 4.1 (100) 19.6 (500) -4

15 -5

16 -6

17 2.2.3 Crumb Rubber Modifier (CRM) Two different sizes were selected to represent the lower and upper size limits of CRM that can be used in asphaltic materials to derive both technical and economic advantages. The largest size CRM was obtained from fines obtained from a tire shredder. The shredded rubber were further screened to obtain a nominal 3 mm coarse rubber particles. This size was determined to be the maximum with respected to reactivity of the particles with asphalt and stress concentration effects which can influence strength and durability properties of the materials. A fine CRM of 180 µm particles retained by 80 Mesh sieve was obtained from Baker, Inc. This was considered to be the smallest size due to economic reasons because cost increases abruptly with decrease in size. However, since reactivity of the rubber particle increases with decrease in size, smaller than 180 µm will be even more desirable as a CRM for asphaltic concrete as far as technical feasibility is concerned. 2.3 MIXTURE DESIGN The Marshall mix design method was used to design bituminons mixtures with or without CRM. First Marshall specimens (4 in. diameter x 2½ in.) were manufactured in accordance with procedure outlined in ASTM D Each specimen was subjected to 50 blows on each end in order to obtain the desired level of compaction. The compacted specimens were tested for bulk specific gravity, stability and -7

18 flow, and density and air voids. specific gravity test was performed in accordance with ASTM D The stability and flow were measured by using Marshall Apparatus in accordance with ASTM D The maximum theoretical specific gravity of mixture (Rice specific gravity) was determined in accordance with ASTM D From the known values of bulk specific gravity and maximum specific gravity, voids in total mix (VTM) was computed. VMA (Voids in the Mineral Aggregate) was determined using the values of bulk specific gravity of the aggregate, the bulk specific gravity of the compacted mixture and the asphalt content by weight of total mix. VFA (Voids Filled with Asphalt) was computed from the known values of VTM and VMA. A total of 24 mixtures were tested using the two Wisconsin DOT mixtures (MV-3 and MV-4). Test data for these mixtures are shown in Tables A-1 through A-24, Appendix A. Test properties such as bulk specific gravity, maximum theoretical bulk specific gravity, air voids, unit weight, VMA, and VFA, stability, and flow were plotted against percent asphalt content by weight of total mix (% AC by weight of Mix), Fig. A-1 through A-24, Appendix A. In this work, optimum asphalt content was determined in accordance with the NAPA procedure outlined in TAS-14 (8). Recommended air void content for the Wisconsin DOT mixtures varies between 3 and 4 percent. Therefore, medium air void content was taken as 3.5 percent. The optimum asphalt content was taken as the -8

19 value of asphalt derived at 3.5% air void content from the curve drawn between air voids and %AC content by weight of total mixture. Other properties such as air voids, VMA, VFA, theoretical maximum bulk specific gravity, bulk specific gravity, unit weight, stability, and flow were determined from their respective plots corresponding to the optimum asphalt content determined above. However, the values of air voids, stability, flow, and VMA were compared with those specified by the Wisconsin DOT for the Marshall design method. When all these values fell within the specification, the optimum asphalt content was considered adequate for actual construction purposes. If any of the above parameters were out of the specification range, the mixtures were redesigned and retested until all the parameters were within acceptable limits per WI-DOT. -9

20 SECTION 3 RESULTS AND DISCUSSION This section describes the effects of asphalt content on properties of asphaltic materials. The effects of inclusion of CRM on performance of the Wisconsin DOT dense-graded asphaltic concrete mixtures (MV-3 and MV-4) are described. 3.1 EFFECT OF ASPHALT The effect of asphalt on properties of the mixtures tested is shown in Tables A-1 through A-24, and in Fig. A-1 through A-24. In general air voids, bulk specific gravity, and maximum theoretical specific gravity decreased, while unit weight, voids filled with asphalt cement (VFA) and flow increased with increasing asphalt content. VMA (Voids in Mineral Aggregates) decreased up to a certain level of asphalt content beyond which it increased. But in some cases, VMA decreased with an increase in asphalt content. The effects of asphalt addition on Marshall stability indicated two different trends. In the first case, the stability increased with asphalt content up to a certain limit, and then decreased. Whereas, in the second case, the stability decreased with increasing asphalt content, and then increased. In order to meet strength and durability requirements for asphaltic pavements, Marshall design criteria have been established for various types of pavements by Wisconsin DOT and other agencies. -1

21 3.2 EFFECT OF INCLUSION OF CRM Various Marshall design parameters corresponding to optimum asphalt content determined at about 3.5% air voids are shown in Tables 3-1 through 3-4. WI-DOT requirements are given in Table 3-5. The effect of CRM on various physical properties of the two WI-DOT asphaltic mixtures is presented in Fig. 3-1 through The effects of inclusion of the 3 mm CRM on the properties of the two Wisconsin DOT mixtures (MV-3 and MV-4) are shown in Tables 3-1 and 3-2 and in Fig. 3-1 through Fig In general, an increase in the 3 mm CRM content caused a decrease in bulk specific gravity, maximum theoretical specific gravity, unit weight, and stability. However, the values of VMA, VFA, and flow increased with addition of the 3 mm CRM (Tables 3-1 and 3-2). Additionally, asphalt cement requirements increased substantially when amounts of the 3 mm CRM was increased from 1% to 9% by weight of total asphalt cement used. At the 9% level, the mixtures did not meet Wisconsin DOT requirements for stability as well as flow (Tables 3-1, 3-2, and 3-5). The influence of the 180 µm CRM on the mixtures are presented in Tables 3-3 and 3-4, and in Fig. 3-8 through The various parameters of the mixtures (MV-3 and MV-4) such as bulk specific gravity, maximum theoretical specific gravity, unit weight, VMA, VFA, and stability were not greatly affected by inclusion of the 180 µm CRM within the experimental range (Fig.3-8 through 3-14). However, when the fine -2

22 CRM (180 µm) was added to the asphaltic mixtures, the flow increased but the values were substantially lower compared to the -3

23 TABLE 3-1: Mixture Design Data for Mix MV-3 Containing 3 mm CRM CRM content (% of AC) Optimu m Asphalt Content Specif ic Gravit y Theo. Max. Sp. Gr. Voids Marshall Data at Optimum AC Content Unit Weight (PCF) VMA VFA Stabilit y (lbs) Flow (0.01 in.) Reco. Mixing Temp. ( F) Dust to Asphalt Ratio

24 TABLE 3-2: Mixture Design Data for Mix MV-4 Containing 3 mm CRM CRM content (% of AC) Optimu m Asphalt Content Specif ic Gravit y Theo. Max. Sp. Gr. Voids Marshall Data at Optimum AC Content Unit Weight (PCF) VMA VFA Stabilit y (lbs) Flow (0.01 in.) Reco. Mixing Temp. ( F) Dust to Asphalt Ratio

25 TABLE 3-3: Mixture Design Data for Mix MV-3 Containing 80 Mesh CRM (180 µm) CRM content (% of AC) Optimu m Asphalt Content Specif ic Gravit y Theo. Max. Sp. Gr. Voids Marshall Data at Optimum AC Content Unit Weight (PCF) VMA VFA Stabilit y (lbs) Flow (0.01 in.) Reco. Mixing Temp. ( F) Dust to Asphalt Ratio

26 TABLE 3-4: Mixture Design Data for Mix MV-4 Containing 80 Mesh CRM (180 µm) CRM content (% of AC) Optimu m Asphalt Content Specif ic Gravit y Theo. Max. Sp. Gr. Voids Marshall Data at Optimum AC Content Unit Weight (PCF) VMA VFA Stabilit y (lbs) Flow (0.01 in.) Reco. Mixing Temp. ( F) Dust to Asphalt Ratio

27 TABLE 3-5: Wisconsin DOT Requirements for MV-3 and MV-4 Mixtures ITEMS MV-3 (GRADATION 3) MV-4 (GRADATION 4) No. blows / end Stability, min. lbs Flow, 0.01 in Voids, percent V.M.A., min. percent Tensile Strength Ratio, percent min. Mixture -no additive 70.0* 70.0* * If an additive is used (lime or liquid) to improve the resistance to moisture damage, the minimum Tensile Strength Ratio shall be 75 percent. -8

28 -9

29 -10

30 -11

31 -12

32 -13

33 -14

34 -15

35 -16

36 -17

37 -18

38 -19

39 -20

40 -21

41 -22

42 mixtures made with the coarse CRM (3mm) for a given CRM content. The asphalt requirements for the rubberized mixtures containing the fine CRM were essentially the same as that for the reference Wisconsin DOT mixture (MV-3 and MV-4) without CRM as shown in Tables 3-3 and 3-4. Additionally, both Wisconsin DOT mixtures containing fine CRM (180 µm) met all the requirements of WI-DOT that are specified for the reference asphaltic mixtures without CRM (Tables 3-3, 3-4, and 3-5). In accordance with the requirements of the generic system (1), the optimum asphalt content is selected based on air voids, as used in this work. This optimum asphalt level should produce stability that should meet the minimum stability requirements for control mixture without CRM. This condition was satisfied for the rubberized mixtures containing the fine (180µM) CRM up to 15% CRM levels. However, in the case of the rubberized mixtures containing the coarse CRM (3 mm), the mixtures did not satisfy this requirement especially at 9% CRM level which is a low level of CRM inclusion. Additionally, the materials made with the 3mm CRM were very sticky and hard to remove from molds. Also, the stability values were much lower than those observed for the mixtures containing 180 µm CRM. The mixtures with the coarse CRM required larger amounts of asphalt compared to that for the materials made with the fine CRM (180 µm) or mixtures without CRM. Therefore, it was concluded that the material made with the coarse CRM is not suitable for construction work. -23

43 SECTION 4 SUMMARY and CONCLUSIONS This study was carried out to establish a modified generic technology for manufacture of rubberized paving materials. For this work, it was decided to use a single size CRM in asphaltic mixtures in order to avoid designing gradation of CRM for individual aggregate gradations of dense-graded asphaltic concrete systems. In order to establish the new technology, it was decided to use two sizes of CRM. A coarse CRM (3mm) was selected as the largest size and a fine CRM (180µM) was taken as the smallest size based on technical and economic factors. Two dense-graded Wisconsin DOT asphaltic mixtures (MV-3 and MV-4) were chosen as reference mixtures. Entire experimental work was divided into two different series. The first series of tests were carried out using the coarse CRM (3mm) and the two Wisconsin DOT mixtures. The second series of tests were conducted using the fine CRM (180µM) and the two Wisconsin DOT mixtures. In the first series of experiments, mixtures were made with the 3mm CRM varying between 1 and 9% percent of total asphaltic cement used. For each mixture, various Marshall properties such as air voids, voids in the mineral aggregates (VMA), void filled with asphalt (VFA), theoretical maximum specific gravity, bulk specific gravity, flow and stability were evaluated using applicable standards. The data observed were -1

44 analyzed for determining optimum asphalt level in accordance with the technique established by the National Asphalt Paving Association (NAPA). The results showed that performance of the control DOT mixtures deteriorated with increasing amounts of the coarse CRM (3mm). Furthermore, asphalt requirements increased substantially even at 9% CRM level compared to the reference mixtures without CRM. The second series of experiments were conducted with the 180 µm CRM varying between 5 and 15% of total asphalt cement content used. In this case most of the CRM particles were expected to react with the asphalt cement due to their high reactivity, and therefore, it would modify the asphalt cement to a marked extent. The remaining unreacting particle should behave like elastic aggregates. All the Marshall properties were also recorded for this series of the investigation. The mixtures containing up to 15% of the fine CRM showed excellent results. All the mixtures containing the fine CRM, not only met the design requirements for asphaltic mixtures, but also did not increase asphalt requirement substantially up to 13% CRM of the asphalt cement used. At the 15% CRM level, the asphalt requirement increased slightly. Based on the analysis of test results, it was concluded that the fine CRM (180 µm) can be used in both the Wisconsin DOT mixtures (MV-3 and MV-4) without any changes in conventional manufacturing technology for asphaltic materials. Thus, it is hoped that the proposed modified generic system in this investigation will have even a greater acceptance compared to the standard generic system due to its ease of -2

45 adoption in commercial applications. More evaluation is needed to use various combination of finer CRM in order to derive both technical as well as economic benefits without changing standard mixture design and production technology for asphaltic paving materials. After developing optimum mixture proportions for the proposed technology, further developmental efforts will be needed for field performance evaluation of this new technology with fine CRM. -3

46 SECTION 5 REFERENCES 1. Naik, T.R., Singh, S.S., and Wandorf, R.B., "Application of Scrap Tire Rubber in Asphaltic Materials: State of the Art Assessment", A Technical Report, Prepared for Wisconsin DNR, Center for By-Products Utilization, Department of Civil Engineering and Mechanics, University of Wisconsin-Milwaukee, July Heitzman, M.A., "State of the Practice: Design and Construction of Paving Materials with Crumb Rubber Modifier", A Technical Report, No. FHWA-SA , May Kandhal, P., and Hanson, D., "Crumb Rubber Modifier Technologies", Proceedings of the Crumb Rubber Modifier Workshop, Merriville, Indiana, February 23-24, Chehovits, J.G., "Design Methods for Hot-Mixed Asphalt-Rubber Concrete Paving Materials", Asphalt Rubber Producers Group National Seminar on Asphalt Rubber, Federal Highway Administration, Naik, T.R., and Singh, S.S., "Utilization of Scrap Tires", Report No. CBU , Department of Civil Engineering and Mechanics, College of Engineering and Applied Science, University of Wisconsin-Milwaukee, April Takallou, M.B., and Takallou, H.B., "Benefits of Recycling Waste Tires in Rubber Asphalt Paving", Transportation Research Record No. 1310, TRB, Washington, D.C., 1991, pp Singh, S.S., "Innovative Application of Scrap Tires", Wisconsin Professional Engineer, July 1993, pp National Asphalt Pavement Association, "Mix Design Techniques - Part I", NAPA TAS-14, April Wisconsin Department of Transportation, Supplemental Specification, SS 4.3, State of Wisconsin, Department of Transportation, Division of Highways, Madison, WI, August REP-236/alb -1

47 APPENDIX A MIX DESIGN DATA BY MARSHALL METHOD -2

48 TABLE A-1: Marshall Properties of Asphaltic Concrete for Mixture No. MV-3(C1). % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

49 -4

50 TABLE A-2: Marshall Properties of Asphaltic Concrete for Mixture No. MV-3(R1) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

51 TABLE A-3: Marshall Properties of Asphaltic Concrete for Mixture No. MV-3(R2) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" ) l

52 TABLE A-4: Marshall Properties of Asphaltic Concrete for Mixture No. MV-3(R3) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

53 TABLE A-5: Marshall Properties of Asphaltic Concrete for Mixture No. MV-3(R4) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

54 -9

55 TABLE A-6: Marshall Properties of Asphaltic Concrete for Mixture No. MV-3(R5) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Comp Mix Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

56 TABLE A-7: Marshall Properties of Asphaltic Concrete for Mixture No. MV-4(C2) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

57 TABLE A-8: Marshall Properties of Asphaltic Concrete for Mixture No. MV-4(R6) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

58 TABLE A-8: Marshall Properties of Asphaltic Concrete for Mixture No. MV-4(R6) (continued) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

59 TABLE A-9: Marshall Properties of Asphaltic Concrete for Mixture No. MV-4(R7) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" ) l

60 TABLE A-10: Marshall Properties of Asphaltic Concrete for Mixture No. MV-4(R8) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

61 TABLE A-11: Marshall Properties of Asphaltic Concrete for Mixture No. MV-4(R9) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

62 TABLE A-12: Marshall Properties of Asphaltic Concrete for Mixture No. MV-4(R10) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

63 TABLE A-13: Marshall Properties of Asphaltic Concrete for Mixture No. MV-3(F1) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )

64 -19

65 TABLE A-14: Marshall Properties of Asphaltic Concrete for Mixture No. MV-3(F2) % AC by wt. of Mix % Rubber by wt. of AC In Mass (g) In Water SSD in Volume (cc) Th. Max. Voids VMA VFB Unit Weight (PCF) Stability (lbs) Measured Adjusted Flow (x 0.01" )