Performance of Hot-Mix Asphalt Containing Recycled Asphalt Pavement

lowest is allowed in heavy-duty wearing courses. The use of RAP per-centages 10% higher than the specified limits requires performing anumber of additional expensive tests.

A review of the available published national and international lit-erature on the feasibility of using high RAP content in HMA revealedthat, theoretically, it is feasible to produce plant recycled hot asphaltmixes with high RAP contents (2). The consensus from the literatureis that 40% RAP is the maximum feasible content with the availablerecycled hot asphalt technologies. Higher contents of RAP wouldrequire the use of indirect heat techniques or warm asphalt tech-nology and involve more processing and testing of RAP to reduceits variability.

Past research has shown that designing mixes containing RAPrequires adjusting the virgin aggregate gradation to account for theRAP aggregate to meet a final blend gradation that will result in rea-sonable volumetric properties (3, 4). Perez et al. used the PradoWindesign software to perform the analytical design of mixes containingdifferent RAP contents (5). The design aimed to match and succeededin very closely matching the grading curves of the mixes of the sametype, but with different percentages of RAP. All binders were selectedto obtain a similar rheological behavior when mixed with the oldbinder in the RAP.

They reported that performance-related laboratory tests showed nosignificant differences between the mixes with “common” percent-ages of RAP and those with “high” percentages of RAP. The perfor-mance tests were also not capable of distinguishing between similarmixes, with and without renewing agents in the binder. Hence, theyconcluded that from a laboratory point of view, the amount of RAPused in HMA can be increased without affecting the performance ofthese mixes, under the conditions that a suitable grading curve can befound and that the new binders are well selected.

Accordingly it was hypothesized that by achieving similar gradingfor the mixes and using a suitable combination of binders, it would befeasible to produce mixes of similar properties. An experimental pro-gram was developed to test this hypothesis. RAP can be used in manyroad-related applications, but the focus of this project is on its use asaggregate in plant HMA for wearing courses. The program involvedlaboratory mix designs and testing of Size 14-mm HMA for wear-ing course applications with 0%, 10%, 20%, and 30% RAP. Thetests included volumetric properties and resilient moduli of the mixes.In this paper, the experimental program is briefly described and theinitial mix designs and results of the laboratory tests conducted sofar are presented and discussed. This program is the first stage of aresearch project being carried out at Swinburne University of Tech-nology on optimizing the content of RAP in HMA. The main pur-pose from this stage of the project is to develop a database forvolumetric and mechanical properties of recycled mixes by usingcurrent Australian practice. The next stage of the project involvesstudying the chemical properties of the old and new binders and

Performance of Hot-Mix AsphaltContaining Recycled Asphalt Pavement

Binh T. Tran and Rayya A. Hassan

121

The purpose of this paper is to report the initial findings of an experimen-tal program to design and assess the properties of recycled hot densegraded asphalt mixes. The mixes include Size 14-mm wearing course mixwith and without recycled asphalt pavement (RAP). The RAP contentsin the recycled mixes were 10%, 20%, and 30%. Laboratory designs ofthe recycled mixes were conducted according to current Australian prac-tice, which requires the use of a gyratory compactor to compact the mixesat 120 cycles and the use of lower-grade binder in mixes with >15% RAPcontent. The mixes, virgin and recycled, were designed to have similarblend gradations and acceptable film indices. The virgin and RAP aggre-gates were sourced from one supplier to ensure consistency throughoutthe project. Binder Grade C320 was used for the virgin mix and for themix with 10% RAP. For the other two recycled mixes, a binder gradeC170 (lower viscosity) was used. Results from the limited laboratorydesign and testing program indicate that despite having similar blend gra-dations and acceptable design film index values, the mixes vary in mostvolumetric properties and in stiffness. However, this design approachproved to be successful in producing recycled mixes with up to 20% RAPthat meet specification requirements. Results also indicate that the addi-tion of RAP leads to reduction in required binder content to achieve 4%air voids content, also a reduction in the value of voids in mineral aggre-gate, voids filled with binder, and film index. Further, the addition ofRAP results in a stiffer mix, and this effect increases with increasingRAP content.

Concern about sustainable development is increasing currently,requiring governments and organizations worldwide to act to pre-serve the environment and natural resources for future genera-tions. The use of reclaimed or recycled asphalt pavement (RAP)in hot-mix asphalt (HMA) applications has both environmentaland economic benefits.

Despite the considerable benefits of using RAP in asphalt pave-ment, its use in Victoria, Australia, has been limited to certain typesof asphalt mixes with limited percentages. This is due to the limitedknowledge about the long-term performance of recycled mixes con-taining RAP and the high costs associated with the additional perfor-mance tests required. VicRoads, the State Road Authority of Victoria,for example, allows the use of RAP in mixes for light- to heavy-dutywearing courses and in heavy-duty structural layers with percentagesranging from 10% to 30% by mass (1). The highest percentage isallowed in fatigue-resistant mixes for structural base course, and the

Swinburne University of Technology, John Street, Hawthorn, Victoria 3122, Australia.Corresponding author: B. T. Tran, [email protected].

Transportation Research Record: Journal of the Transportation Research Board,No. 2205, Transportation Research Board of the National Academies, Washington,D.C., 2011, pp. 121–129.DOI: 10.3141/2205-16

mixes to better understand their interaction and identify ways tooptimize RAP content.

RAP CHARACTERISTICS AND EFFECTS ON PROPERTIES AND PERFORMANCE OF RECYCLED HMA

RAP consists of milled or excavated asphalt pavement that is crushedand screened into different sizes to meet specified grading require-ments. The most important characteristic of RAP material that wouldgreatly influence the properties and performance of the resulting recy-cled mix is the stiffness of its binder. The recovered RAP binder isstiffer than virgin binders as a result of aging. The physical effectsof aging are caused by chemical changes in the binder caused by theeffects of high temperatures during production and oxidation (amongother mechanisms) during service life (6, 7). Accordingly, when RAPis used in HMA, the effects of aging on its binder properties needto be considered in the mix design together with the further agingexpected during the production of recycled HMA as a result of theelevated temperatures.

The aim of designing HMA containing RAP is to optimize theRAP content and achieve a mix with good performance in fatigue,rutting, thermal resistance, and overall durability in addition to sta-bility and compactability requirements. Further, there is the need tomeet required volumetric properties including air voids, voids inmineral aggregates (VMA), and film index (FI) of the final mix (7 ).The two factors that play a significant role in achieving the requiredvolumetric and mechanical properties of a mix containing RAP arethe blend aggregate gradation and properties and the blending betweenvirgin and recycled binders.

To meet a final blend gradation that will result in acceptable vol-umetric properties, it is recommended that, because RAP is finematerial with high surface area, the virgin aggregate gradation mayneed to be adjusted to account for the RAP aggregate (3).

Research findings indicate that RAP does not act as black rockand that partial blending of RAP binder and virgin binder occursto a significant extent (4, 8, 9). Accordingly it was concluded that100% contribution of the RAP recovered binder to the new recycledmix should be assumed. Austroads (the association of Australian andNew Zealand road transport and traffic authorities) also recommendsassuming 100% contribution (10). This means that the amount ofvirgin binder can be reduced by the full amount of asphalt binder inthe RAP for the percentage specified.

Daniel and Lachance reported that if the RAP material is not heatedsufficiently, the RAP binder does not blend with the virgin binder tothe extent possible (11). Because the RAP particles have a coarsergradation than the RAP aggregate, the overall mix gradation will becoarser if the RAP particles do not completely break down and blendwith the virgin materials. Accordingly, with the same compactioneffort, an increase in VMA is expected. They concluded that there isan optimal preheating time for RAP to allow for the greatest extent ofblending between the virgin and RAP materials.

The mechanical performance of HMA containing RAP varies withRAP content. It has been found that the performance of pavementswith properly prepared recycled asphalt mixes in regard to fatigue, rut-ting, thermal resistance, and durability proved to be satisfactory (7).Generally, literature review shows that the stiffness and rutting resis-tance of the mix increase with increasing RAP content and, generally,increasing the stiffness of asphalt mix decreases fatigue life.

The stiffness of a mix can be affected by the aggregate and grada-tion, but the most significant factor is the stiffness of the binder in the

122 Transportation Research Record 2205

recycled mix (12). To reduce the effect of binder stiffness on the finalmix, softer (lower grade) binders are used. Researchers have foundthat mixes with up to 20% RAP require no change in binder grade orviscosity, but at higher percentages they recommended that binderproperties should be adjusted (4, 8, 9). Accordingly, Austroads (10)and VicRoads (1) recommend the use of softer binder when RAPcontent is >15%.

EXPERIMENTAL PROGRAM

A laboratory experimental program was carried out to design and testthe volumetric and mechanical properties of hot asphalt mixes con-taining 0%, 10%, 20%, and 30% RAP. Important details of thetesting program are highlighted below:

• Mix type was VicRoads Type H Size 14 mix, a heavy-duty mixused in wearing and regulating courses in most heavily traffickedpavements (1).

• The mixes were designed to have similar blend gradation andacceptable film index.

• Samples were prepared by using a gyratory compactor at 120cycles when assessing volumetric and mechanical properties, whichincluded the following:

– Volumetric properties. Volumetric properties are air voids con-tent (AV), VMA, voids filled with binder (VFB), absorbed binder(b), bulk density (ρbulk), maximum density (ρmax), and binder FI.

– Mechanical performance. Indirect tensile modulus (stiffness).VicRoads specification requires performing other tests includingwheel tracking, moisture sensitivity, and fatigue; however; theresults of these tests were not available at the time this paper wasbeing written (1).• Current practice in Victoria is to use Binder Grade C320 in

Type H mix with 0% and 10% RAP. For mixes with >15% RAP, alower-grade binder, C170, has to be used. Also full blending of RAPand virgin binders is assumed.

– C320 properties. Density is 1,042.2 kg/m3, dynamic viscosityat 600°C is 302 Pa s, and penetration at 48 mm/10.

– C170 properties. Density is 1,041.0 kg/m3, dynamic viscosityis 152 Pa s, and penetration at 80 mm/10.

Materials

The virgin aggregates, fillers, and RAP were sourced from the samesupplier to ensure consistency among the mixes. The coarse virginaggregates with sizes 14 mm, 10 mm, and 7 mm are basalt crushedrock. The fine materials include minus-5 dust, which is basalt crusherfine, asphalt sand, and limestone (filler, 1%) (1). The RAP is materialmilled from an asphalt pavement surface that has been processed to amix of 10-mm maximum nominal size aggregate. Use of this sizeRAP helps achieve a continuous particle size distribution when mixedwith the virgin aggregates.

The fundamental tests to verify the properties of componentmaterials of the virgin aggregate and RAP were carried out. The prop-erties included particle size distribution of the virgin aggregates andRAP. Other relevant properties of the virgin aggregates were providedby the supplier and were found to comply with the requirementsof relevant VicRoads specification. Properties include bulk density,water absorption, rock quality (soundness), and flakiness index forthe coarse aggregate. For the crusher fine and sand, they include the

degradation factor, plasticity index, and percent clay and fine silt. RAPbinder content was also determined by extraction using the solventmethod and found to be 4.6% (13).

Mix Design

Mix Gradation

Design gradations for the virgin and recycled mixes are shown inTable 1 together with the maximum and minimum limits set out inVicRoads specification for H14 mix (1). The design proportions ofthe component materials for the recycled mixes were determined byconsidering the following:

• Achieving a blend gradation similar to that of the virgin mix;• Ensuring that the film index values are acceptable, that is, rea-

sonably close to the limits set out in the VicRoads specification(1); and

• Controlling the proportion of fines passing the 0.075-mm sieve.

Tran and Hassan 123

The design FI values for each mix at different binder contents areshown in Table 2.

Design Binder Content

The mixes were prepared by using the design proportions of the com-ponent materials. For each mix, three batches were prepared at threedifferent binder contents. The binder contents for the virgin and 10%RAP mixes were 4.%, 5.3%, and 6.3%. For the mixes with 20% and30% RAP, they were 4.1%, 5.1%, and 6.1%. Past research has shownthat the blending of virgin and RAP binders occurs to a significantextent, almost close to total blending (14). In addition, total blend-ing occurs when there is an optimum preheating time of RAP beforemixing (11). Current practice in Victoria also assumes total blendingof binders, and the recommended preheating duration of RAP is 2 h.Accordingly, when the recycled mixes for this project were designed,the full amount of RAP binder was deducted from the total bindercontent to determine the amount of virgin binder required in eachmix. The proportions of virgin and RAP binders calculated in the

TABLE 1 Mix Design Gradation for Virgin and Recycled Mixes

Mix Type Specification

Sieve Size (mm) Virgin 10% RAP 20% RAP 30% RAP Max. Min.

19.0 100 100 100 100 100 100

13.2 99 99 99 99 100 85

9.5 84 83 84 84 84 70

6.7 71 64 65 65 73 59

4.75 57 50 52 51 65 48

2.36 39 35 37 36 48 32

1.18 30 28 30 28 37 22

0.600 23 23 24 23 28 14

0.300 16 16 17 16 22 10

0.150 7.58 7.20 8.06 8.70 14 6

0.075 5.23 4.89 5.53 6.12 7 4

Combined density 2.717 2.717 2.712 2.712(t/m3)

TABLE 2 Design Parameter for Virgin and Recycled Mixes

Total Binder Virgin Binder RAP Binder Designed Effective SurfaceMix Type in Mix (%) in Mix (%) in Mix (%) Binder (%) Area FI (μm)

Virgin 4.3 100 0 4 5.7 7.25.3 100 0 5 5.7 9.16.3 100 0 6 5.7 11.0

10% RAP 4.3 89 11 4 5.5 7.55.3 91 9 5 5.5 9.56.3 93 7 6 5.5 11.5

20% RAP 4.1 77 23 4 5.9 6.65.1 82 18 5 5.9 8.46.1 85 15 6 5.9 10.2

30% RAP 4.1 66 34 4 6.1 6.45.1 73 27 5 6.1 8.16.1 78 22 6 6.1 9.9

design for all mixes are shown in Table 2 together with otherdesign parameters, including designed effective binder contentsand surface areas.

Laboratory Testing Program

As mentioned before, performance of the virgin mix and the three recy-cled mixes was tested through their volumetric properties and resilientmoduli. The tests were carried out in accordance with the testing pro-cedures set out in the Australian Standards for HMA as highlightedbelow. In total, 12 batches (9 kg each) were prepared for use in test-ing the properties of the four mixes. Each batch consists of two loose800-g samples for maximum density tests, one loose 850-g sample forbinder extraction test, four compacted samples for bulk density tests,and four compacted samples for modulus tests.

Volumetric Properties

• ρmax of asphalt mix was determined by using water displacementmethod set out in AS 2891.7.1–2004 (15).

• ρbulk of compacted asphalt sample was determined by using thepresaturation method set out in AS 2891.9.2–2005 (16).

• AV, VMA, VFB, b, and FI were calculated by using the formulas provided in AS 2891.8–2005 (17 ).

Mechanical Properties

The resilient moduli of the different mixes were determined byusing the indirect tensile test procedure described in AS 2891.13.1–1995 (18).

RESULTS AND DISCUSSION

For each of the four mixes, the above tests were carried out and theresults were plotted against the relevant binder contents. The designbinder contents for these mixes were then estimated from the relevantdesign curves (AV versus binder content). The design binder contentis that required to achieve 4% air voids content. Volumetric proper-ties of the four mixes at their design binder contents were also esti-


mated from the relevant graphs. Common mix design practice wouldinvolve preparing new batches at the design binder contents to test theproperties of the mixes. An example for estimating the volumetricproperties and elastic modulus of the mix with 20% RAP at designbinder content is demonstrated in Figures 1 through 4.

Figure 1 shows an estimate of design binder content at 4% airvoids; Figure 2a and 2b demonstrates estimating VFB and VMA atdesign binder content, respectively; Figure 3a and 3b shows estimatesfor effective binder and absorbed binder contents at design bindercontent, respectively; and estimates for FI and resilient modulusvalues at design binder content are presented in Figure 4a and 4b,respectively.

The estimated design binder contents, volumetric properties, andmoduli of the virgin (0% RAP) and recycled mixes (10%, 20%, and30% RAP) at their design binder contents are summarized in Table 3.The results of design binder content and VMA at different RAP con-tents are presented graphically in Figure 5a and 5b, respectively. Thevariations of FI and modulus with RAP content are presented in Fig-ure 6a and 6b, respectively. A summary of observations from thesefigures and Table 3 is provided next.

Figure 5a shows that with increasing RAP content, there is a reduc-tion in design binder content required to achieve the same air voidscontent. It decreases by about 0.2% when RAP content is increasedby 10%.

Figure 5b also indicates that VMA decreases with increasing RAPcontent, which can be related to a number of elements as discussedbelow:

• The reduction in design binder content leads to a reduction ineffective binder content and, ultimately, VMA value.

• VMA is most affected by the amount of material passing the0.075-mm sieve and the relative proportions of coarse and fine aggre-gates. The latter is the same for all mixes. However, increasing theamount of material passing the 0.075-mm sieve will result in a greatertotal surface area of the aggregate blend, which results in a thin-ner average film thickness, lower effective binder content, and lowerVMA (19). The proportions of the fine materials <0.075 mm in therecycled mixes (Table 1) increase with increasing RAP content andtheir effects on surface area and effective binder are evident inTables 2 and 3, respectively, and on FI, as can be seen in Figure 6a.

• Binder absorption decreases with increased viscosity of thebinder. Binders that are more viscous tend to limit absorption by

FIGURE 1 Binder content at 4% air voids—20% RAP.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

4.0 4.5 5.0 5.5 6.0 6.5

Air

vo

id (

%)

Binder content (%)

5.05

FIGURE 2 Values at design binder content—20% RAP: (a) VFB and (b) VMA.

40

50

60

70

80

90

100

14.4

14.6

14.8

15.0

15.2

15.4

15.6

15.8

16.0

16.2

4.0 4.5 5.0 5.5 6.0 6.5

4.0 4.5 5.0 5.5 6.0 6.5V

MA

(%

)V

FB

(%

)

Binder content (%)

Binder content (%)

(b)

(a)

5.05

5.05

14.8

74.4

0.00

0.10

0.20

0.30

0.40

0.50

0.60

4.0 4.5 5.0 5.5 6.0 6.5

Ab

sorb

ed b

ind

er -

b (

%)

Binder content (%)(b)

Binder content (%)(a)

5.05

5.05

4.7

0.39

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

4.0 4.5 5.0 5.5 6.0 6.5

Eff

ecti

ve b

ind

er -

Be

(%)

FIGURE 3 Contents at design binder content—20% RAP mix: (a) effectivebinder and (b) absorbed binder.

aggregates because of a lack of fluidity and inability to fill aggregatepores (19, 20). Using C170 binder in the 20% and 30% RAP recycledmixes has clearly contributed to increased binder absorption (0.3%,0.4%, and 0.6%, respectively, for 10%, 20%, and 30% RAP) leadingto lower effective binder and lower VMA (see Table 3).

As expected, and reported by many researchers, the resilient mod-uli of mixes containing RAP are higher than for the virgin mix becauseof the higher stiffness of RAP aged binder (Figure 6b). This effect ishigher when higher RAP content is present in the mix.

These results indicate that regardless of having similar blend gra-dations, the mixes vary in most volumetric properties. These varia-tions can be attributed to the differences in the proportions of fines,binder viscosity, and also to the level of blending between the old and

the new binders. Although the volumetric properties of the recycledmixes vary from the virgin mix and among each other, the propertiesof the mixes with 10% and 20% RAP comply with the minimumrequirements of current VicRoads specification in regard to VMA(minimum 15), FI (minimum 8), and elastic modulus (1). The mixwith 30% RAP, however, does not meet the minimum require-ments of the current specification and will need to be redesignedto reduce the amount of fines to reduce surface area and increaseFI and VMA values.

To study the effects of the increase in resilient modulus on pave-ment response, analysis using CIRCLY 5 was performed for a full-depth asphalt pavement whose wearing course is Type H14 with 0%,10%, 20%, and 30% RAP (21). The pavement composition includesa 50-mm Surfacing Layer Type H14 overlaying an Intermediate

FIGURE 4 Values at design binder content—20% RAP mix: (a) FI and(b) resilient modulus.

(a)

(b)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

4.0 4.5 5.0 5.5 6.0 6.5

FI (

%)

Binder content (%)

5.05

8.2

4000

4200

4400

4600

4800

5000

5200

5400

Binder content (%)

5.05

4903.7

4.0 4.5 5.0 5.5 6.0 6.5

Res

ilien

t M

od

ulu

s (M

Pa)

TABLE 3 Properties of Virgin and Recycled Mixes at 4% Air Voids Content

Design BinderMix RAP % ρmax (t/m3) ρbulk (t/m3) AV (%) VMA (%) VFB (%) Content (%) b (%) Be (%) FI (μm) Modulus (MPa)

Virgin 0 2.520 2.416 4.0 16.3 75 5.9 0.7 5.2 9.5 3,609

10% RAP 10 2.523 2.420 4.0 15.6 74 5.3 0.3 5.0 9.4 4,415

20% RAP 20 2.533 2.433 4.0 15.0 73 5.1 0.4 4.7 8.1 5,082

30% RAP 30 2.551 2.447 4.0 14.2 72 4.9 0.6 4.3 7.2 6,909

NOTE: Be = effective binder content.


Tran and Hassan 127

FIGURE 5 Variations in (a) design binder contents and (b) VMA values withdifferent RAP contents.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

0 10 20 30

Des

ign

Bin

der

(%

)

RAP content (%)

14.0

14.5

15.0

15.5

16.0

16.5

0 10 20 30

VM

A (

%)

RAP content (%)

(a)

(b)

Asphalt Layer Type SI20 on an Asphalt Base Layer Type SF20 (SI and SF are standard structural hot asphalt mixes) (1). The asphaltbase is supported by a crushed rock subbase layer with Californiabearing ratio (CBR) 15% and a subgrade with CBR 3%, which is the VicRoads recommended arrangement for full-depth asphaltpavements (22).

Relevant elastic material properties of the different layers weredetermined and used as input into CIRCLY. For each of the four pave-ment designs, the same design traffic loading (9.8 × 106 standard axlerepetitions), subgrade support, design speed (60 km/h), and wearingcourse thickness (intermediate and surfacing) were used.

In this analysis, the critical strain and cumulative damage factor—ratio of the design loading to the allowable traffic loading—valueswere fixed for the base layer. The aim of the analysis is to determinethe level of saving in base thickness that can be achieved when RAPis incorporated in the surfacing layer.

The results are presented in Table 4 and show that the criticalstrains in the surfacing layer change from compressive to tensile whenRAP is used in the surface layer of pavement. This indicates that thehigher stiffness of the surface layer enables it to withstand the stressesinduced by traffic loading and also helps reduce the stresses trans-ferred to the base layer. Ultimately, lower thicknesses are required forthe critical base layer to resist the expected loading over the designlife of the pavement. As can be seen from Table 4, the thickness of thebase layer drops by 3, 6, and 11 mm when 10%, 20%, and 30% RAPis used in the surface layer, respectively.

CONCLUSIONS

Results from the limited laboratory design testing program for hotasphalt mixes with 0%, 10%, 20%, and 30% RAP indicate that despitehaving similar blend gradations and reasonably close FI values, themixes vary in most volumetric properties and stiffness. Althoughthe properties are not similar, they meet the minimum performancerequirements set out in VicRoads specification for the nominatedmix type. Accordingly it can be concluded that this approach, sofar, has proved to be successful in designing H14 recycled mixeswith acceptable properties up to 20% RAP. Below is a summary ofthe findings:

• The addition of RAP leads to reduction in design binder con-tent, VMA, VFB, and FI.

• Adding RAP results in a stiffer mix, and this effect increaseswith increasing RAP content.

• Limited theoretical analysis shows that using recycled HMAcontaining RAP in the surfacing layer of a full-depth asphaltpavement helps reduce the total pavement thickness for the samemaximum tensile strains at the bottom of the base layer. Theseinitial findings indicate that the use of recycled HMA in pavementsurfacing layers is advantageous, in regard not only to saving in pavement thickness but also to saving in binder content and disposal fees.


3000

3500

4000

4500

5000

5500

6000

6500

7000

7500

0 10 20 30

Mo

du

lus

(MP

a)

RAP content (%)

7.0

7.5

8.0

8.5

9.5

9.0

10.0

0 10 20 30

FI (

µm

)

RAP content (%)

(b)

(a)

FIGURE 6 Variations in (a) FI values and (b) resilient moduli with differentRAP contents.

TABLE 4 Results of CIRCLY Analysis

No. Layer Thickness (mm) Material Description Critical Strains CDF

1 Surface (virgin) 50 Asphalt size 14 mm, Type H, no RAP 1.38 E−05 1.08 E−30Intermediate 70 Asphalt size 20 mm, Type SI, 60 km/h −3.47 E−05 1.30 E−03Base 104 Asphalt size 20 mm, Type SF, 60 km/h −1.62 E−04 1.01 E+00Subbase 150 Crushed rock, CBR 15% 2.16 E−04 5.78 E−05Subgrade 0 In situ subgrade CBR 3% 5.04 E−04 2.15 E−02

2 Surface (10% RAP) 50 Asphalt size 14 mm, Type H, 10% RAP −8.21 E−06 2.46 E−05Intermediate 70 Asphalt size 20 mm, Type SI, 60 km/h −4.94 E−05 7.59 E−03Base 101 Asphalt size 20 mm, Type SF, 60 km/h −1.62 E−04 1.01 E+00Subbase 150 Crushed rock, CBR 15% 2.22 E−04 6.88 E−05Subgrade 0 In situ subgrade CBR 3% 4.98 E−04 1.99 E−02



Further research needs to be conducted to develop design methodsand testing conditions including protocols for sample preparation thatare suitable for producing recycled mixes with high RAP contents(>20%) and acceptable volumetric and mechanical properties.

ACKNOWLEDGMENTS

The authors express their sincere gratitude for the support receivedin undertaking this research from George Giannakenas and Bob Bodyof VicRoads, State Road Authority of Victoria, and Tom Melvin ofBoral, a major asphalt supplier in Australia.

REFERENCES

1. Code of Practice for Registration of Bituminous Mix Designs. RC500.01. VicRoads, 2008, pp. 1–7.

2. Hassan, R. A. Feasibility of Using High RAP Contents in Hot Mix Asphalt(CD-ROM). Australia Asphalt Pavement Association, 2009, pp. 1–15.

3. McDaniel, R. S., G. A. Huber, and V. Gallivan. Conserving Resourcesand Quality with High RAP Content Mixes. Hot Mix Asphalt Technol-ogy (HMAT) Magazine, Vol. 11, No. 6, 2006, pp. 44–46.

4. Al-Qadi, I., S. Carpenter, G. Roberts, H. Ozer, Q. Aurangzeb, M. Elseifi,and J. Trepanier. Determination of Usable Residual Asphalt Binder inRAP. Illinois Center for Transportation, Rantoul, 2009.

5. Perez, F., M. Rodriguez, J. De Visscher, A. Vanelstraete, and L. De Bock.Design and Performance of Hot Mix Asphalts with High Percentages ofReclaimed Asphalt: Approach Followed in the Paramix Project. Proc.,3rd Eurasphalt and Eurobitume Congress, Vienna, Austria, 2004.

6. Sondag, M. S., B. A. Chadbourn, and A. Drescher. Investigation of Recy-cled Asphalt Pavement (RAP) Mixtures. Department of Civil Engineering,University of Minnesota, Minneapolis, 2002.

7. Al-Qadi, I. L., M. Elseifi, and S. H. Carpenter. Reclaimed AsphaltPavement—A Literature Review, Series No. 07-001. Illinois Center forTransportation, Rantoul, 2007.

8. Chen, J. S., P. Y. Chu, Y. Y. Lin, and K. Y. Lin. Characterization ofBinder and Mix Properties to Detect Reclaimed Asphalt Pavement Con-tent in Bituminous Mixtures. Canadian Journal of Civil Engineering,Vol. 34, No. 5, 2007, pp. 581–588.

9. McDaniel, R., and R. M. Anderson. NCHRP Report 452: RecommendedUse of Reclaimed Asphalt Pavement in the Superpave Mix Design Method:

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Technician’s Manual. TRB, National Research Council, Washington,D.C., 2001.

10. Austroads Guide to Pavement Technology. Part 4b, Asphalt. Austroads,Sydney, Australia, 2007.

11. Daniel, J. S., and A. Lachance. Mechanistic and Volumetric Properties ofAsphalt Mixtures with Recycled Asphalt Pavement. In Transporta-tion Research Record: Journal of the Transportation Research Board,No. 1929, Transportation Research Board of the National Academies,Washington, D.C., 2005, pp. 28–36.

12. Rebbechi, J., and M. Green. Going Green: Innovations in RecyclingAsphalt. Presented at Australian Asphalt Pavement Association (AAPA)Pavements Industry Conference, Surfers Paradise, Queensland, Australia,2005.

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15. AS 2891.7.1-2004: Methods of Sampling and Testing Asphalt—Determination of Maximum Density of Asphalt—Water DisplacementMethod. Standards Australia, 2004, pp. 1–3.

16. AS 2891.9.2-2005: Methods of Sampling and Testing Asphalt—Determination of Bulk Density of Compacted Asphalt—PresaturationMethod. Standards Australia, 2005, pp. 1–3.

17. AS 2891.8-2005: Methods of Sampling and Testing Asphalt—Voids andDensity Relationships for Compacted Asphalt Mixes. Standards Australia,2005, pp. 1–5.

18. AS 2891.13.1-1995: Methods of Sampling and Testing Asphalt—Determination of the Resilient Modulus of Asphalt—Indirect TensileMethod. Standards Australia, 2005, pp. 1–7.

19. Chadbourn, B. A., E. L. J. Skok, N. L. Crow, S. Spindler, and D. E.Newcomb. The Effect of Voids in Mineral Aggregate (VMA) on Hot-MixAsphalt Pavements. Minnesota Department of Transportation, St. Paul,2000.

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21. CIRCLY 5 User Manual. MINCAD Systems Pty. Ltd., Victoria, Australia,2009.

22. Code of Practice for Selection and Design of Pavements and Surfacings.RC 500.22. VicRoads, 2010, pp. 1–19.

The Committee for the 10th International Conference on Low-Volume Roadspeer-reviewed this paper.

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Performance of Hot-Mix Asphalt Containing Recycled Asphalt Pavement