Rutting evaluation of hydrated lime and SBS modified asphalt mixtures for laboratory and field compacted samples

Construction and Building Materials 25 (2011) 756–765

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Rutting evaluation of hydrated lime and SBS modified asphalt mixtures for laboratory and field compacted samples Halit Özen * Yildiz Teknik Üniversitesi, Civil Engineering Department, Istanbul, Turkey

a r t i c l e

i n f o

Article history: Received 12 April 2010 Received in revised form 15 July 2010 Accepted 18 July 2010 Available online 21 August 2010 Keywords: Asphalt mixtures SBS polymer Hydrated lime LCPC test Repeated creep test Moisture conditioning Correlation

a b s t r a c t The purpose of this study is to evaluate permanent deformation for hydrated lime and SBS modified asphalt mixtures. Control (C), 2% hydrated lime (2L), 5% SBS polymer mixtures and 2%hydrated lime– 5%SBS (2L5SBS) mixtures were prepared. The Laboratoire Central des Ponts et Chaussées (LCPC) wheel tracker, also known as French Rutting Tester were realized with two different stages. Same LCPC slabs were produced. Original LCPC compactors and also field cylinder were used separately. LCPC rutting values were determined with left and right wheel loadings. Also averages were obtained with calculation. Repeated creep tests were used for these mixtures and permanent deformations were plotted for two different moisture conditioning that water immersion and freeze and thaw cycles. Diameter samples (100 mm and 150 mm) were studied in repeated creep tests. In the result that LCPC tracking values were compared with repeated creep tests in terms of sample diameters. LCPC wheel-tracking test results show that 2L5SBS mixtures reveal utmost performance according to the other mixtures types. Polymer modification increased rutting resistance of lime modified ones. Both original LCPC compactor and field cylinder compaction showed resemble results. 150 mm samples showed highest correlation (higher than R2 = 0.80) between LCPC test and repeated creep test for different compaction types and different moisture conditionings. Ó 2010 Elsevier Ltd. All rights reserved.

1. Introduction Moisture damage and permanent deformation are the primary modes of distresses in hot-mix asphalt (HMA) pavements. The performance of HMA pavements is related to cohesive and adhesive bonding within the asphalt–aggregate system. The loss of cohesion (strength) and stiffness of the asphalt film, and the failure of the adhesive bond between aggregate and asphalt in conjunction with the degradation or fracture of the aggregate were identified as the main mechanisms of moisture damage in asphalt pavements. The loss of adhesion is due to water leaking between the asphalt and the aggregate and stripping away the asphalt film. The loss of cohesion is due to the softening of asphalt concrete mastic. Moisture damaged pavement may be a combined result of these two mechanisms. Further the moisture damage is a function of several other factors like the changes in asphalt binders, decreases in asphalt film thickness, changes in aggregate quality, increased widespread use of selected design features, and poor quality control. Moisture susceptibility of hot-mix asphalt (HMA) pavements continues to be

* Corresponding author. Address: Yildiz Technical University, Faculty of Civil _ Engineering, Department of Civil Engineering, 34210 Esenler, Istanbul, Turkey. Tel.: +305 348 1393; fax: +(305) 348 2802. E-mail address: ozenh@fiu.edu 0950-0618/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.conbuildmat.2010.07.010

a major pavement distress. As moisture damage reduces the internal strength of the HMA mix, the stresses generated by traffic loads increase significantly and lead to premature rutting, raveling and fatigue cracking of the HMA layer [1]. Additives have been used for improving performance of HMA pavements to various distresses (i.e., permanent deformation, moisture damage, and fatigue or low-temperature cracks). There are numbers of different additives available, which can be introduced directly to the asphalt cement (AC) as a binder modifier, or can be added to the mixture with the aggregate [2]. Hydrated lime has shown multifunctional effects in hot-mix asphalt (HMA) mixtures. Numerous studies have demonstrated that hydrated lime in asphalt mixtures can reduce pavement rut-depth because of its distinct stiffening effects, moisture-associated damage by improving the aggregate–asphalt bonding, and long-term oxidative aging potential. Several experimental studies have also shown that hydrated lime can reduce asphalt cracking to some extent despite its stiffening effects because the initial microcracks can be intercepted and deflected by tiny, active lime particles. Because of the latest observations that hydrated lime is an efficient material for improving fatigue cracking resistance as well as rutting, which is not a typically observed phenomenon from other materials, the effects of hydrated lime as a crack resister have remained unsolved questions and have not been fully understood

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in the asphalt pavement community. Moreover, not many studies have been conducted to investigate the crack-resistant characteristics of hydrated lime-treated mixtures with different application rates. Since stiffer mixtures are generally more susceptible to cracking, the crack-resistant characteristics of hydrated lime might be degraded from certain critical amounts of lime added, whereas the rut-resistant potential of mixtures can still be enhanced [3]. Polymers, which are the most commonly used additives in binder modification, can be classified into four main categories, namely plastics, elastomers, fibres and coatings. To achieve the goal of improving bitumen properties, a selected polymer should create a secondary network or new balance system within bitumens by molecular interactions or by reacting chemically with the binder. The formation of a functional modified bitumen system is based on the fine dispersion of polymer in bitumen for which the

Table 1 Engineering properties of the used aggregate. Properties

Test method

Value

L.A. Abrasion (%) Flakiness (%) Stripping resistance (%) Water absorption (%) Soundness in NaSO4 (%) Polished stone value Plasticity index for sandy aggregate

ASTM C-131 BS 812 (Part 105) ASTM D-1664 ASTM C-127 ASTM C-88 BS 812 (Part 114) TS 1900

9.6 14.7 30–35 0.85 4.06 0.60 Non-plastic

Table 2 Aggregate specific gravities (g/cm3). Grain-size fraction

Apparent specific gravity

Bulk specific gravity

Coarse aggregate Fine aggregate Filler aggregate Aggregate mixture

2.894 2.889 2.910 2.893

2.832 2.751 – 2.803

Table 4 Properties of the used hydrated lime (SKK 80-T).

Table 3 The results of tests performed on asphalt cement (AC 60–70). Properties

Test method

Specific gravity (25 °C) Softening point (°C) Flash point (Cleveland) Penetration (25 °C) Ductility (25 °C)

ASTM ASTM ASTM ASTM ASTM

D-70 D36-76 D-92 D-5 D-113

Unit 3

g/cm °C °C 0.1 mm cm

Value

Chemical properties

Method

Value

1.019 52 210 67 100+

Total CaO (%) Active Ca(OH)2 (%) MgO (%) Total CaO + MgO (%) Loss of ignition (%) Insoluble in acid (%) R2O3 (%) SO3 (%) CO2 (%) Physical properties Sandy-over 90 micron Density (kg/m3)

EN 459-2 TS 32 EN 459-2 TS EN 459 TS 32 TS 32 EN 459 EN 459

85.78 82.04 3.52 89.3 22.51 1.41 0.47 1.47 3.89

EN 459 EN 459

6 472

100 90

Percentage Passing, %

chemical composition of bitumens is important. Among polymers, the elastomer styrene–butadiene–styrene (SBS) block copolymer is the most widely used one. It has been identified that styrene–butadiene–styrene (SBS) triblock copolymer can obviously improve the mechanical properties of mixtures such as aging, permanent deformation, low temperature cracking, moisture damage resistance, and so on. Researchers have carried out laboratory experiments related to the effects of styrene–butadiene–styrene and lime on the moisture susceptibility of asphalt concrete mixtures. However limited experimental studies have been conducted for evaluating the effect of usage of SBS and lime together on the water damage of hot-mix asphalt [1]. For a polymer to be effective in road applications, it should blend with the bitumen and improve its resistance (to rutting, abrasion, cracking, fatigue, stripping, bleeding, aging, etc.) at medium and high temperatures without making the modified bitumen too viscous at mixing temperatures or too brittle at low temperatures. In other words, it must improve the overall performance of the pavement. Many polymers have been used in the modification process but thermoplastic elastomers are enjoying wide acceptance as road bitumen modifiers [4]. In the laboratory a wheel-tracking device simulates a vehicle to evaluate permanent deformation of the slab by rut depth. Rut depth is regarded as an appropriate indicator for comparing the susceptibility of mixtures to permanent deformation. The Wheeltracking method, however, cannot be used to determine the modulus of the mixture used by thickness design procedures and therefore the rut depth cannot be used in mechanistic pavement analysis. Furthermore, the rut depth of a slab is a total deformation which includes deformation caused by densification. Densification is affected by the compression method and the grading of the mixture; therefore the rut depth of a slab varies widely from mixture to mixture [5]. The dynamic creep test is an interesting alternative to the wheel-tracking test for measuring the sensibility for permanent deformations, but there is some doubt about the ability of the traditional method to be able to work as a functional method of measurement and to distinguish between different types of mixes [6].

80 70 60 Table 5 Summary of Marshall design results.

50 40

Design parameters

Values

30 20 10 0 0,01

0,10

1,00

10,00

Sieve Size, mm Fig. 1. Aggregate distribution on gradation chart.

100,00

Bulk specific gravity, Gmb Marshall stability (kg) Air voids, Pa (%) Void filled with asphalt, Vf (%) Flow, F, 1/100 in. Filler/bitumen Asphalt cement, Wa

2.510 1530 4 72 3.2 1.17 5.15

Board specification in Turkey Min.

Max.

– 900 3 75 2 –

– – 5 85 4 1.5

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H. Özen / Construction and Building Materials 25 (2011) 756–765

Fig. 2. Second conditioning system.

SMA mixtures or else stony skeleton mixes [7]. Unlike this research continuous gradation was offered and the result was that repeated creep test and wheel-tracking test did not give parallel result. The evaluation of the dynamic creep test showed that the test can be used as an indicator of potential rutting, but the results in these cases should be confirmed with other more reliable tests. Also it is thought that gradation changing is more important than compacting effecting types in view of evaluating efficiency of rutting test methods [8]. Pavements built lime-treated bitumen should have relatively greater resistance to rutting at the temperatures and also greater resistance to transverse thermally induced cracking at low temperatures. Based on the data at these two temperature extremes, it is tempting to speculate that, at some intermediate temperature, for example 25 °C, asphalt concrete mixtures containing the lime-treated bitumen should have superior resistance to failure during repeated load during fatigue testing and increased resistance to fatigue cracking in pavements [9].

Table 6 Repeated creep test parameters. Temperature Conditioning stress Conditioning stress time Conditioning stress rest time Test stress Loading period Time loaded Time unloaded Pulse number Resting time

40 °C 10 kPa 1 min 1 min 100 kPa 1000 ms (1sn) 500 ms 500 ms 64800 (18 h) 15 min

LCPC wheel-tracking test and repeated creep test gave similar results for selected SMA mixtures. In terms of rutting tests it was thought that repeated creep tests may be a good indicator of

Table 7 RCT test deformations for 100 mm diameter samples. Pulses

Freeze–thaw cycled samples (100 mm diameter)

1 10 50 100 501 1000 5011 10000 19952 30045 39810 50118 64730

Water immersed samples (100 mm diameter)

2L5SBS9

2L5SBS10

2L9

2L10

C7

C6

C2

C3

2L6

2L7

2L5SBS9

2L5SBS8

83 296 555 694 1009 1167 1631 1844 2059 2172 2200 2237 2246

131 327 523 654 924 1073 1426 6411 6686 6836 6902 6987 7024

104 207 292 330 500 612 950 1137

212 617 1118 1387 2052 2369 2988 3239 3490 3683 3761 3838 3935

144 385 722 945 1649 2006 2740 2982 3233 3359 3466 3534 3631

124 474 1005 1318 2194 2548 3286 3536 3775 3900 3986 4053 4130

340 1279 2479 3024 4178 4596 5423 5774 6088 6297 6440 6573 6716

299 1169 2577 3364 5015 5523 6304 6556 6753 6940 7071 7202 7333

278 773 1334 1614 2262 2543 3144 3378 3613 3754 3866 3932 4044

226 705 1184 1428 1992 2236 2734 2969 3204 3336 3439 3524 3599

503 1305 2025 2344 3019 3282 3847 4064 4281 4366 4432 4508 4564

791 2212 3379 3784 4415 4622 5055 5224 5375 5459 5506 5563 5619

Table 8 RCT test deformations for 150 mm diameter samples. Pulses

1 501 1000 3004 5011 10000 19952 30045 39810 50118 64730

Freeze–thaw cycled samples (150 mm diameter)

Water immersed samples (150 mm diameter)

C7

C8

C9

2L4

2L5

2L6

2L5SBS4

2L5SBS5

2L5SBS6

C1

C2

C3

2L1

2L2

2L3

2L5SBS1

2L5SBS2

2L5SBS3

170 1790 2300 3203 3644 4256 4913 5309 5570 5777 5984

54 681 870 1230 1437 1735 2039 2192 2300 2389 2479

100 2129 2688 3602 4001 4521 5077 5414 5613 5785 5957

117 1771 2507 3469 3766 4215 4638 4862 5042 5168 5321

144 2206 2754 3672 4095 4661 5157 5392 5563 5707 5887

143 2659 3307 4361 4856 5487 6234 6756 6963 7144 7342

133 1688 2060 2695 2988 3378 3777 3981 4123 4247 4354

162 3115 3955 5341 5966 6750 7481 7878 8130 8330 8538

135 1661 1995 2529 2783 3129 3483 3683 3828 3937 4046

135 2138 2626 3424 3789 4354 4874 5120 5357 5521 5712

163 3031 3648 4700 5217 6079 6787 7223 7513 7713 7967

118 1548 2039 2904 3250 3760 4197 4415 4615 4716 4734

163 1686 2101 2918 3300 4145 4917 5353 5570 5697 6123

375 5852 6812 8425 9192 10219 11235 11777 12136 12412 12689

100 2475 3103 4180 4754 5420 6023 6311 6482 6599 6735

152 1640 2070 2877 3280 3862 4409 4732 4938 5099 5243

244 3407 3994 4924 5348 5854 6440 6712 6947 7056 7138

135 1638 2023 2624 2930 3305 3643 3885 4090 4162 4180

H. Özen / Construction and Building Materials 25 (2011) 756–765

The purpose of this research is to study rutting of lime and SBS polymer modified asphalt mixtures. In this context LCPC wheeltracking tests were realized with both original LCPC compactor and field road cylinder prepared samples. Repeated creep tests were done. Different moisture conditionings were applied. Correlation between 100 mm and 150 mm diameter samples and LCPC tests was investigated.

2. Materials Used materials and experimental procedures in this study were following. Aggregate combination and asphalt cement were used. Aggregate combination was obtained from the Sularbasi rock quarry. Various engineering properties of coarse and fine aggregate were given in Tables 1 and 2. Regional factors were observed and 60–70 penetration asphalt cement produced from Kirikkale Oil Refinery was used. Test results for asphalt cement are incorporated in Table 3. Gradation curve are represented in Fig. 1. Hydrated lime (HL) was selected as a modifying agent. HL was added to the mixture as a part of filler material. Properties of the used HL were illustrated in Table 4. Hydrated lime filler was used as 2%. Filler was replaced with the lime.

Fig. 3. LCPC wheel tracking values for LCPC compacter (left wheel). Fig. 6. LCPC wheel tracking values for field roller compacter (right wheel).

Fig. 4. LCPC wheel tracking values for field roller compacter (left wheel).

Fig. 5. LCPC wheel tracking values for LCPC compacter (right wheel).

759

Fig. 7. LCPC wheel tracking values for LCPC compacter (averages).

Fig. 8. LCPC wheel tracking values for field roller compacter (averages).

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H. Özen / Construction and Building Materials 25 (2011) 756–765

SBS polymer (Kraton D 1101) was incorporated directly to the bituminous binder. Modification was realized in laboratory. 60–70 penetration bitumen was heated to a temperature 180 °C before SBS powder was added. The blend mixture was mixed at a low speed during 10 min because of homogeneous mix. Mixture was stirred up vigorously for about 30 min using laboratory mixer after additive blending operation. Kraton D polymers are elastic and flexible. The inclusion of butadiene or isoprene influences the properties of the end product. Marshall method (ASTM D1559) was used for determining optimal bitumen content for conventional and modified asphalt mixtures. Three identical samples were produced for all alternatives. Bitumen range region was regulated according to the bitumen demand for each mixture and asphalt briquettes were fabricated. Compacting energy was applied as 50 blows. The results of Marshall test are presented in Table 5. Cylindrically produced samples were researched in view of permanent deformation. For this purpose damage mechanisms were applied to half of the samples two different moisture conditioning system were applied. In the first conditioning conditioned samples were kept in 50 °C water for 48 h and after 48 h in the room temperature. This process was repeated as three stages. In the second system samples were located in 15 °C freezer for 72 h. Plastic bags were used. After 72 h samples were waited in room temperature for 24 h. These processes were also repeated as three steps. Fig. 2 shows a section from the second conditioning. Control, 2%lime and 2%lime–5%SBS polymer mixtures were produced. Performance tests were realized with these unconditioned and conditioned samples.

modified mixtures were interrogated and correlation between these tests were studied for different sample diameters (100 mm and 150 mm samples). 3.1. Repeated creep tests

LCPC wheel-tracking tests both original LCPC compactor and field rollers were applied. Repeated creep tests were researched with two different conditioning. Lime, SBS polymer and lime–SBS

The implementation of a suitable test for assessing resistance to accumulated permanent deformation under repeated loading, which leads to wheel track rutting, is probably the most important requirement for performance-based specifications. This is because a wide range of mixture parameters, not least those associated with the aggregate, affects it. By contrast, elastic stiffness and fatigue are principally controlled by the binder characteristics and volumetric proportions of the mixture and can be estimated on the basis of past research for conventional materials. It was for these reasons that the uniaxial static creep test was introduced in the 1970s. It is now recognized that repeated loading is a necessary requirement; hence the repeated load axial test was developed at Nottingham. This was done originally very much in the context of mixture design [10]. Cylindrical samples of the HMA were subjected to repeated load creep test in Universal Materials Testing Apparatus (UMATTA) process (NAT tester). Unconfined repeated load uniaxial creep test were realized with selected test parameters illustrated in Table 6. Repeated creep tests were realized with conventional and modified asphalt mixtures. Both HL and SBS polymer modification were

Table 9 LCPC rutting values for original LCPC compacted control samples.

Table 10 LCPC rutting values for original LCPC compacted 2%lime modified samples.

3. Permanent deformation tests

Left sample

Dp = 2515

Left sample

Dp = 2431

Cycle Value N/°C

1000 24 °C

1000 60 °C

3000 60 °C

5000 60 °C

10,000 60 °C

30,000 60 °C

50,000 60 °C

Cycle Value N/°C

1000 24 °C

1000 60 °C

3000 60 °C

5000 60 °C

10,000 60 °C

30,000 60 °C

50,000 60 °C

A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3

7.59 7.73 6.97 9.75 9.68 9.49 10.40 10.00 9.14 8.74 10.45 10.74 7.77 8.94 8.85

8.78 9.59 8.57 11.18 11.74 11.13 12.17 12.39 11.03 9.76 12.66 12.60 9.12 10.97 10.49

9.36 9.84 8.65 11.48 12.10 11.70 12.26 12.79 11.97 10.30 13.16 12.97 9.57 11.51 10.89

9.40 9.90 9.61 11.58 12.50 11.74 12.30 13.14 12.29 10.60 13.57 13.36 9.63 11.76 11.11

9.45 10.61 9.66 11.98 12.97 12.49 12.93 13.60 12.66 10.64 13.60 13.82 9.75 11.98 11.34

10.68 11.55 10.20 13.18 14.13 13.43 13.77 14.76 13.58 11.85 15.11 14.56 10.52 13.17 12.20

10.96 12.12 10.77 13.68 14.83 13.83 14.23 15.32 14.21 12.22 15.69 15.17 11.08 13.41 12.68

A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3

9.48 9.68 9.92 8.99 9.68 10.29 8.38 8.61 8.10 5.76 6.34 6.92 4.58 4.16 5.98

10.41 10.76 10.96 10.22 11.25 11.54 9.86 10.35 9.66 7.39 8.42 8.30 6.40 5.36 7.43

11.58 11.85 11.47 10.64 11.94 12.18 10.17 11.19 10.29 8.10 8.88 8.79 6.90 6.25 7.78

11.80 12.36 11.68 10.82 12.31 12.22 10.43 11.50 10.75 8.38 9.00 9.18 7.17 6.60 8.31

11.95 12.38 12.06 11.19 12.72 12.70 11.09 12.35 11.56 8.89 9.21 9.55 7.47 6.80 8.40

12.58 12.98 12.65 12.00 13.65 13.48 11.42 12.76 11.59 9.79 10.08 10.30 8.06 7.39 9.20

12.68 13.49 13.03 12.79 13.99 13.76 11.75 13.27 12.14 9.97 10.35 10.61 8.73 7.48 9.52

AVRG = %Rut =

9.08 –

10.81 1.73

11.24 2.15

11.50 2.42

11.83 2.75

12.85 3.76

13.35 4.26

AVRG = %Rut =

7.79 –

9.22 1.43

9.87 2.08

10.17 2.38

10.55 2.76

11.20 3.40

11.57 3.78

E3 E2 E1 D3 D2 D1 C3 C2 C1 B3 B2 B1 A3 A2 A1 AVRG = %Rut =

11.44 9.68 10.53 11.80 10.34 11.27 11.31 11.46 10.84 11.17 9.94 9.63 7.08 4.71 7.77 9.93 –

13.14 12.40 12.53 13.59 13.35 14.00 13.05 14.16 12.90 12.78 12.59 11.22 10.38 6.56 9.17 12.12 2.19

13.54 13.07 12.83 13.70 14.11 14.69 13.69 14.75 13.28 13.12 13.27 12.39 10.64 7.19 9.66 12.66 2.73

13.56 13.95 12.86 14.44 14.67 15.24 13.75 15.15 13.70 13.38 13.63 12.64 10.83 7.32 9.78 12.99 3.06

14.26 14.50 13.56 14.66 15.40 15.67 14.54 15.77 13.93 13.91 14.37 13.32 10.98 8.42 10.36 13.58 3.65

15.78 16.36 15.26 16.87 17.90 18.14 16.05 17.85 15.53 15.86 16.45 15.19 12.36 9.84 11.53 15.40 5.47

16.61 17.54 16.08 17.48 18.80 18.76 17.49 18.20 16.41 16.83 16.90 15.84 13.31 10.46 12.40 16.21 6.28

E3 E2 E1 D3 D2 D1 C3 C2 C1 B3 B2 B1 A3 A2 A1 AVRG = %Rut =

8.97 9.12 8.16 9.89 9.21 8.15 8.96 9.31 8.90 8.67 8.06 8.11 6.79 7.92 6.16 8.43 –

10.92 10.81 9.79 11.61 11.11 9.95 10.70 11.13 10.61 10.04 9.88 9.54 7.39 8.96 7.80 10.02 1.59

11.56 11.65 10.48 12.06 11.93 10.83 10.96 11.91 11.39 10.83 10.81 10.98 9.53 10.00 8.79 10.91 2.49

11.91 12.00 10.76 12.35 12.29 11.04 11.50 12.30 11.40 10.87 11.84 10.99 9.60 10.14 9.27 11.22 2.79

12.34 12.64 11.18 12.79 12.84 11.51 11.62 12.97 12.06 11.70 12.11 11.96 9.93 10.93 9.82 11.76 3.33

13.24 13.88 12.24 13.88 14.21 12.68 12.70 14.12 13.18 12.71 13.48 12.37 10.90 12.14 10.98 12.85 4.42

13.79 14.59 12.78 14.46 14.88 13.19 13.37 14.81 13.62 13.44 14.21 13.61 11.59 12.82 11.54 13.51 5.09

CYCLE = AVRG%RUT =

1000 –

1000 1.96

3000 2.44

5000 2.74

10,000 3.20

30,000 4.62

50,000 5.27

CYCLE = AVRG%RUT =

1000 –

1000 1.51

3000 2.28

5000 2.58

10,000 3.05

30,000 3.91

50,000 4.43

Right sample

Dp = 2505

Right sample

Dp = 2436

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H. Özen / Construction and Building Materials 25 (2011) 756–765

applied. In aggregate blending filler content was 6.0% of total gradation (C-conventional control). Filler content was decreased 2%. HL was used as 2% of total filler (6%) contents. 2% lime (2L), 2% lime–5%SBS (2L5SBS) polymer synergistic mixtures were produced. Two identical samples for 100 mm diameter samples and three identical samples for 150 mm samples were used. Environmental conditioning systems were introduced interested samples. In repeated creep tests duration two replicate samples were used for each mixtures and samples were produced carefully. For some pulse time’s creep values were presented in Tables 7 and 8. Identical samples were prepared with great care because of angularity effects of used rock combination. Although, generally, wheel-tracking tests appear to be well correlated with rutting in the field, there are at present no quantified relationships to link wheel-tracking test results to rutting in the field under variable traffic loading and environmental conditions. For this reason, wheel-tracking tests cannot as yet be used to provide a quantitative estimate of rutting in the field. The test does, however, provide a reliable estimate of the rutting potential and, hence, can be used to rank mixes according to rut potential. Wheel-tracking tests are particularly recommended for the evaluation of rutting performance of stone–skeleton mixes, or mixes that include modified binders. Experience has shown that these mix types cannot be properly evaluated by means of conventional tests such as the unconfined uniaxial static or dynamic creep tests [8]. Although different polymer modifiers were used such as elastomeric or plastomeric polymers, drainage inhibitors, mostly higher-

Rutting test was verified with the LCPC method. This test has been used in France for over 20 years to successfully prevent rutting in HMA pavements. In recent years, the test has been used in the United States. This test is capable of simultaneously testing two HMA slabs. Slab dimensions are typically 180 mm wide, 500 mm long, and 20–100 mm thick. Research indicates good correlation between LCPC test results and actual field performance [11,12]. Samples were prepared at 500 mm length, 180 mm width, 100 mm height. Test temperature was 60 °C. Samples were kept at least 12 h at this temperature. Each tire was applied 5000 N load. Tire pressure was 0.6 MPa (87 psi). Samples must be compacted as a determined degree of compacting. Test briquettes were compacted at 98% field compacting scale. Before the temperature was reached at 60 °C, precompacting (1000 cycles) was made. Pre-conditioning temperature was regulated and values were saved. After the values were saved rutting was calculated with Y = A  (N/1000)B where A: rutting for 1000 cycle, N: cycle number, B: tangent of linear line in logarithm coordinates. Two identical samples were used for each alternative. LCPC rutting test results

Left sample

Dp = 2438

Cycle Value N/°C

1000 24 °C

1000 60 °C

3000 60 °C

5000 60 °C

10,000 60 °C

30,000 60 °C

50,000 60 °C

A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3 ORTL = _ = %TIO

3.75 6.11 7.21 6.33 7.03 6.18 5.93 6.59 7.59 4.84 4.96 7.17 4.84 5.24 6.29 6.00 –

4.83 7.85 8.16 7.26 8.33 7.60 7.14 8.03 8.54 6.27 6.85 8.38 6.32 6.71 7.43 7.31 1.31

5.28 8.60 8.53 7.53 9.18 8.10 7.19 8.58 8.60 6.39 7.13 8.81 6.70 7.35 7.81 7.72 1.71

5.98 8.71 8.79 7.62 9.24 8.30 7.26 8.89 8.80 6.64 7.89 8.87 6.81 7.42 7.86 7.94 1.93

6.13 8.95 9.13 8.02 9.65 8.49 7.44 8.91 9.50 6.92 8.24 8.94 7.19 7.94 8.46 8.26 2.26

6.70 9.98 9.48 8.41 10.22 9.24 7.84 9.14 10.08 7.57 9.11 9.33 7.77 8.67 9.12 8.84 2.84

7.52 10.06 9.58 8.51 10.27 9.35 8.04 9.50 10.08 7.79 9.54 10.04 7.82 8.71 9.20 9.07 3.06

Right sample

3.2. LCPC wheel-tracking tests

Table 12 LCPC rutting values for original LCPC compacted 2%lime 5%SBS samples.

Table 11 LCPC rutting values for original LCPC compacted 5%SBS modified samples. Left sample

performance levels were observed in all tests [8]. Repeated creep tests on Marshall Samples may be used for explaining permanent deformation [10].

Dp = 2417

E3 E2 E1 D3 D2 D1 C3 C2 C1 B3 B2 B1 A3 A2 A1

8.46 6.07 6.43 8.19 7.43 7.46 8.04 6.38 8.42 5.65 3.75 6.09 5.57 4.12 2.58

9.09 6.38 7.82 8.99 8.72 8.60 8.94 7.70 9.65 6.63 5.64 8.34 6.50 5.56 3.79

9.18 6.43 7.90 9.00 9.10 8.69 9.18 8.15 9.72 7.10 6.34 8.53 6.80 5.72 5.05

9.54 6.49 7.95 9.07 9.25 8.71 9.24 8.55 9.90 7.38 6.38 8.77 7.00 6.37 5.92

9.68 6.95 8.21 9.25 9.53 9.23 9.44 8.79 9.98 7.51 6.92 8.84 7.12 6.45 6.25

10.13 7.40 8.59 10.58 9.95 9.69 9.79 8.88 10.00 7.86 7.04 9.26 7.44 7.26 9.21

10.21 7.44 8.73 10.65 9.98 9.74 9.81 8.94 10.34 7.95 7.10 9.27 7.47 7.35 9.22

ORTL = _ = DEVIR

6.31 1000

7.49 1000

7.79 3000

8.03 5000

8.28 10,000

8.87 30,000

8.95 50,000

ORT%TIO =

–

1.25

1.60

1.83

2.11

2.70

2.85

Dp = 2389

Cycle Value N/°C

1000 24 °C

1000 60 °C

3000 60 °C

5000 60 °C

10,000 60 °C

30,000 60 °C

50,000 60 °C

A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3 AVRG = %Rut =

5.25 4.66 4.92 4.42 4.47 7.11 7.40 7.94 7.41 5.50 6.75 6.59 4.50 6.83 4.32 5.87 –

5.82 5.06 5.14 5.04 5.96 7.95 7.48 8.66 8.36 6.20 7.65 7.14 5.16 7.77 5.22 6.57 0.70

6.00 5.55 5.25 5.25 6.49 8.35 7.56 8.94 8.59 6.27 8.21 7.56 5.39 7.99 5.52 6.86 0.99

6.14 5.68 5.66 5.30 6.53 8.50 7.89 9.01 8.76 6.37 8.25 7.60 5.55 8.13 5.73 7.01 1.14

6.20 5.69 5.93 5.41 6.83 8.57 8.10 9.20 8.90 6.60 8.34 7.65 5.73 8.31 5.75 7.15 1.28

6.38 5.85 6.15 5.80 7.29 9.02 8.18 9.45 9.34 6.71 8.42 7.82 5.92 8.51 5.89 7.38 1.51

6.47 5.88 6.18 6.09 7.85 9.03 8.37 9.69 9.50 7.08 8.59 7.91 6.07 8.68 6.25 7.58 1.70

E3 E2 E1 D3 D2 D1 C3 C2 C1 B3 B2 B1 A3 A2 A1 AVRG = %Rut =

3.25 5.35 5.62 3.68 5.77 5.54 5.52 5.85 8.43 4.91 7.34 7.67 4.42 5.10 6.20 5.64 –

4.38 6.08 6.62 4.69 7.15 6.81 6.54 7.33 9.77 5.80 8.88 8.83 5.30 6.77 7.25 6.81 1.17

4.83 6.71 7.08 4.90 7.42 7.02 6.75 7.75 10.00 6.29 9.50 9.26 5.45 7.33 7.91 7.21 1.57

5.12 6.90 7.15 5.11 7.44 7.04 7.14 7.91 10.06 6.30 9.59 9.54 5.67 7.35 8.57 7.39 1.75

5.21 7.26 7.22 5.23 7.79 7.32 7.50 8.25 10.21 6.55 9.72 9.63 5.69 7.66 8.64 7.59 1.95

5.59 7.67 7.56 5.44 8.05 7.44 7.61 8.45 10.55 6.67 10.05 9.70 6.15 7.79 9.14 7.86 2.21

5.84 7.87 7.84 5.67 8.25 7.66 7.69 8.59 10.60 6.90 10.26 9.92 6.20 8.09 9.38 8.05 2.41

CYCLE = AVRG%RUT =

1000 –

1000 0.94

3000 1.28

5000 1.44

10,000 1.61

30,000 1.86

50,000 2.06

Right sample

Dp = 2401

762

H. Özen / Construction and Building Materials 25 (2011) 756–765

for conventional and modified mixtures are shown in Figs. 3–8. Conventional mixtures show the highest permanent deformation in this test for all compaction types. For the laboratory mixes, it was the intention to assess most HMA mix types currently used in South Africa. These included both stone–skeleton mixes (stone–mastic asphalt and semi-open asphalt with bitumen–rubber binder) and sand-skeleton mixes (gap- and continuously graded asphalt). Porous asphalt was not included. The Transportek wheel-tracking test gave reasonable results, and is recommended for all high reliability projects. The test is appropriate for all mix types, including mixes containing modified binders and stone–skeleton mixes. For Stone–skeleton mixes, the test must be performed at the refusal air void content otherwise the mix could deform excessively, which is not expected if the mix is well compacted in the field provided that it is designed correctly. Because the dynamic creep does not correctly determine the rutting resistance of all mixes, and the performance ratings do not agree with the Transportek wheel-tracking test, the dynamic creep test is not recommended for assessing the rutting potential of HMA other than sand-skeleton mixes manufactured with unmodified binders, unless evaluated in conjunction with other rutting tests. The evaluation of the dynamic creep test showed that the test can be used as an indicator of potential rutting, but the results in these cases should be confirmed with other more reliable tests [8].

The usual testing methods (Marshall test, wheel-tracking test, repeated load uniaxial test) are inadequate for the characterization of the resistance to the permanent deformation of asphalt. This is not to say that these tests would be unsuitable for other applications, for example, in a mixture design procedure within given composition limits. However, reliable comparisons of the deformation behavior of various sorts of mixtures are not possible on the basis of these tests [13]. The efficiency of SBS polymer additive was clearly observed at high temperature (40 °C) for both static and repeated creep tests. The pre-modified (PM) mixtures showed slightly increased resistance to the permanent deformation than the laboratory-modified (M) mixtures. The static creep test was found to be a good indicator of the permanent deformation resistance at high temperature (40 °C) for conventional and modified mixtures. The repeated creep test was shown to be a good indicator of rutting and the superior performance of polymer-modified mixtures in terms of rutting was clarified for the dense skeleton. It was clearly observed that at the higher temperature (40 °C) all conventional samples disintegrated and cracking planes were obtained; however, the modified samples retained their structural integrity. The modification with SBS was very effective in increasing the rutting resistance of a mixture. A rut depth reduction of 25% was obtained with modified mixtures at high temperature at the end of static creep test duration. When the modified mixtures measured at 40 °C showed higher resistance to rutting by factors of between

Table 13 LCPC rutting values for field roller compacted control samples.

Table 14 LCPC rutting values for field roller compacted 2%lime modified samples.

Left sample

Dp = 2490

Left sample

Dp = 2400

Cycle Value N/°C

1000 24 °C

1000 60 °C

3000 60 °C

5000 60 °C

10,000 60 °C

30,000 60 °C

50,000 60 °C

Cycle Value N/°C

1000 24 °C

1000 60 °C

3000 60 °C

5000 60 °C

10,000 60 °C

30,000 60 °C

50,000 60 °C

A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3 AVRG = %Rut =

6.64 6.52 6.36 4.74 5.28 4.61 5.02 4.57 3.53 3.90 2.87 3.05 3.07 3.72 2.29 4.41 –

10.12 9.84 7.58 8.88 8.74 6.12 7.10 7.48 5.36 7.08 6.32 4.44 6.39 6.86 4.76 7.14 2.73

10.53 10.40 8.15 9.36 9.65 6.68 8.30 8.45 5.78 8.02 7.51 5.02 7.40 7.91 5.61 7.92 3.51

10.88 11.61 8.48 9.71 10.10 7.36 8.75 9.02 6.11 8.62 8.15 5.30 7.84 8.48 6.05 8.43 4.02

11.48 11.90 8.76 10.48 10.70 7.75 9.67 9.67 6.64 9.30 8.95 5.95 8.32 8.87 6.65 9.01 4.59

11.89 12.00 9.13 11.28 11.64 8.55 10.29 10.93 7.45 10.23 9.85 6.36 8.94 9.65 7.07 9.68 5.27

12.26 12.10 9.28 11.62 12.03 8.84 10.96 11.56 7.97 10.63 10.29 6.69 9.24 9.71 7.22 10.03 5.62

A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3 AVRG = %Rut =

7.16 6.57 6.43 7.16 7.17 7.28 6.56 6.63 7.16 6.47 6.37 7.36 6.98 7.34 8.00 6.98 –

9.30 9.23 8.45 9.47 9.76 9.04 9.82 9.72 8.53 9.91 9.81 8.84 10.04 10.25 8.81 9.40 2.42

9.68 9.68 9.20 9.91 10.09 9.42 10.19 10.02 8.87 10.25 10.18 9.24 10.54 10.50 9.16 9.80 2.82

9.93 10.02 9.55 10.24 10.53 9.76 10.37 10.34 9.05 10.48 10.44 9.40 10.69 10.71 9.33 10.06 3.08

10.36 10.35 9.54 10.45 10.79 9.97 10.95 10.75 9.26 10.87 10.90 9.73 11.00 11.03 9.70 10.38 3.40

10.83 10.99 10.13 11.07 11.49 10.45 11.44 11.33 9.69 11.40 11.48 9.90 11.36 11.31 9.86 10.85 3.87

11.15 11.21 10.39 11.59 11.77 10.54 12.06 11.83 9.93 11.90 11.90 10.55 11.65 11.66 10.00 11.21 4.23

Right sample

Dp = 2470

Right sample

Dp = 2405

E3 E2 E1 D3 D2 D1 C3 C2 C1 B3 B2 B1 A3 A2 A1 AVRG = %Rut =

3.87 3.64 2.49 3.56 2.80 2.48 2.83 2.50 2.15 3.47 2.82 2.24 3.68 3.32 3.08 3.00 –

5.59 7.77 5.97 5.12 7.46 7.04 5.32 7.39 6.31 5.51 7.65 6.84 5.72 8.69 7.08 6.63 3.64

6.46 9.21 6.95 6.30 9.27 8.66 6.26 9.30 8.14 6.42 9.34 8.36 6.06 9.94 7.95 7.91 4.91

7.03 9.95 7.72 7.66 10.62 9.82 7.15 10.53 9.41 7.39 10.34 9.03 6.63 10.06 8.62 8.80 5.80

7.63 10.84 8.51 8.95 12.20 11.22 8.15 12.24 11.24 8.73 11.70 10.32 7.21 11.11 8.80 9.92 6.93

8.61 11.96 9.75 10.95 14.30 13.26 10.20 14.34 13.61 10.45 13.72 12.18 8.19 12.59 10.55 11.64 8.65

9.12 12.41 10.23 11.85 14.94 13.52 10.99 15.27 14.66 11.44 14.69 12.86 8.70 13.18 11.03 12.33 9.33

E3 E2 E1 D3 D2 D1 C3 C2 C1 B3 B2 B1 A3 A2 A1 AVRG = %Rut =

3.65 3.76 4.21 4.70 4.62 4.10 5.72 5.60 5.31 6.66 6.67 6.37 6.39 6.00 5.95 5.31 –

5.67 5.68 6.09 6.88 6.76 6.71 8.49 8.20 7.95 8.69 9.14 8.84 9.06 8.69 9.02 7.72 2.41

6.00 6.02 6.38 7.32 7.33 7.28 9.05 9.03 8.64 9.33 9.95 9.35 9.48 9.57 9.44 8.28 2.96

6.19 6.18 6.53 7.60 7.66 7.57 9.15 9.35 8.93 9.55 10.26 9.76 9.63 9.90 9.63 8.53 3.21

6.42 6.44 6.67 7.91 8.20 7.91 9.25 9.85 9.41 9.63 10.61 10.21 10.03 10.18 9.97 8.85 3.53

6.69 6.96 7.01 8.12 8.59 8.44 9.75 10.47 9.82 10.08 11.32 10.78 10.22 10.66 10.29 9.28 3.97

6.85 7.23 7.25 8.31 9.27 8.93 9.84 10.79 10.20 10.41 11.82 11.24 10.37 10.98 10.65 9.61 4.30

CYCLE = AVRG%RUT =

1000 –

1000 3.18

3000 4.21

5000 4.91

10,000 5.76

30,000 6.96

50,000 7.47

CYCLE = AVRG%RUT =

1000 –

1000 2.42

3000 2.89

5000 3.15

10,000 3.47

30,000 3.92

50,000 4.26

763

H. Özen / Construction and Building Materials 25 (2011) 756–765

6 and 10 in comparison with the conventional ones at the end of repeated creep duration [14]. Tables 11–17 gives LCPC wheeltracking test results for both original LCPC compactor and field roller. Tables 9–15 shows LCPC wheel-tracking test results for field roller compacted samples. LCPC rutting tests showed parallel results in view of the different compaction types as it shown in Figs. 3–8. Left and right wheels in tests and averages of two showed harmonious results. Lime and SBS polymer modified asphalt mixtures showed highest performance to the rutting according to the lime modified and control mixtures. It was shown that LCPC compactor shows good correlation with the real field roller. Field roller compacted samples showed higher permanent deformation than the LCPC compactor. It is thought that higher void contents can be concerned in highway pavements. Laboratory prepared samples for both compacted cylindrically samples (Marshall Compaction) and slabs (wheel tracking compactors) gives higher rut resistance because of the compaction simulation differences. The results of five testing programs were presented. For the first program, a motorway from Austria was used. Cores were extracted from the motorway and recombined into beams for testing. The selected motorway was one of the most heavily trafficked in Austria and had rut depths of 3 mm after 16 months. Results of FRT (LCPC) testing indicated that rutting was 6% after 30,000 cycles. This was less than the typically recommended 10% maximum for highly

trafficked roadways. Therefore, concluded that for the Austrian motorway, the FRT (LCPC) accurately predicted that the HMA structure would resist deformation [15]. The assessment of the resistance towards rutting is carried out by considering the ratio between the depth rut after 30,000 cycles at a temperature of 60 °C and the total thickness of the sample before testing. For such kind of mixture like EME, maximum rutting considering the French standards (LCPC) is 8%, and it is suggested 5% for heavy traffic [16]. In this research 30000 cycles rutting was evaluated. Original LCPC compacted average rutting ratios (%) for 30000 cycles were found as control: 4,62, 2%lime: 3,91, 5%SBS: 2,70 and 2%lime–5%SBS: 1,86. In addition to this field roller LCPC ratios were calculated as averages in 30000 cycles. This ratios are control: 6,96, 2%lime: 3,92 and 2%lime–5%SBS: 3,06. All mixtures passed acceptance criteria. 2L5SBS mixtures showed doubled performance according to the 2L mixtures for LCPC original compacting. Repeated creep test results for 100 mm and 150 mm diameter samples were compared with LCPC tests for two different compaction efforts. Correlation coefficients were presented in Figs. 9–12. Regression analysis between repeated creep tests and LCPC wheel-tracking tests in terms of 100 mm and 150 mm diameter samples were studied. Figs. 9–12 compare correlation between LCPC field roller and 100 mm–150 mm samples. Higher correlation was obtained with the 150 mm samples. Enlarging the sample to a diameter of 150 mm while the platen is kept at normal size, i.e.,

Table 15 LCPC rutting values for real field cylinder compacted 2%lime 5%SBS samples.

Table 16 LCPC rutting values for field roller compacted 2%lime modified samples.

Left sample

Dp = 2396

Left sample

Dp = 2400

Cycle Value N/°C

1000 24 °C

1000 60 °C

3000 60 °C

5000 60 °C

10,000 60 °C

30,000 60 °C

50,000 60 °C

Cycle Value N/°C

1000 24 °C

1000 60 °C

3000 60 °C

5000 60 °C

10,000 60 °C

30,000 60 °C

50,000 60 °C

A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3 AVRG = %Rut =

0.92 1.16 1.90 0.35 0.11 0.29 0.27 0.10 0.10 1.01 0.89 0.44 0.57 0.20 0.60 0.59 –

4.45 5.07 4.22 3.75 3.21 2.03 2.52 2.01 1.36 3.00 2.72 2.26 2.39 2.22 2.22 2.90 2.30

5.18 5.06 4.76 4.33 3.36 2.38 3.02 2.46 1.90 3.59 3.21 2.59 2.76 2.98 2.38 3.33 2.74

5.23 5.80 4.80 4.43 3.62 2.67 3.29 2.52 1.99 3.94 3.37 2.73 2.86 3.40 2.41 3.54 2.94

5.49 6.00 5.11 4.67 3.88 2.70 3.67 2.75 2.20 4.19 3.73 2.99 3.06 3.98 2.70 3.81 3.21

5.78 6.25 5.20 4.93 4.15 2.92 3.91 2.92 2.61 4.37 4.14 3.30 3.27 4.27 3.00 4.07 3.47

5.96 6.30 5.32 5.10 4.30 3.06 3.98 3.07 3.00 4.48 4.18 3.37 3.51 4.30 3.10 4.20 3.61

A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3 AVRG = %Rut =

7.16 6.57 6.43 7.16 7.17 7.28 6.56 6.63 7.16 6.47 6.37 7.36 6.98 7.34 8.00 6.98 –

9.30 9.23 8.45 9.47 9.76 9.04 9.82 9.72 8.53 9.91 9.81 8.84 10.04 10.25 8.81 9.40 2.42

9.68 9.68 9.20 9.91 10.09 9.42 10.19 10.02 8.87 10.25 10.18 9.24 10.54 10.50 9.16 9.80 2.82

9.93 10.02 9.55 10.24 10.53 9.76 10.37 10.34 9.05 10.48 10.44 9.40 10.69 10.71 9.33 10.06 3.08

10.36 10.35 9.54 10.45 10.79 9.97 10.95 10.75 9.26 10.87 10.90 9.73 11.00 11.03 9.70 10.38 3.40

10.83 10.99 10.13 11.07 11.49 10.45 11.44 11.33 9.69 11.40 11.48 9.90 11.36 11.31 9.86 10.85 3.87

11.15 11.21 10.39 11.59 11.77 10.54 12.06 11.83 9.93 11.90 11.90 10.55 11.65 11.66 10.00 11.21 4.23

E3 E2 E1 D3 D2 D1 C3 C2 C1 B3 B2 B1 A3 A2 A1 AVRG = %Rut =

2.53 2.18 2.38 2.29 0.20 2.54 2.10 1.49 1.79 2.11 2.41 2.64 2.43 2.44 2.78 2.15 –

4.09 4.28 4.81 3.91 4.23 4.48 3.58 3.51 3.75 3.34 3.81 4.41 4.02 3.99 3.48 3.98 1.83

4.37 4.65 5.23 4.18 4.74 5.17 3.74 3.97 4.34 3.62 4.14 4.62 4.36 4.30 3.87 4.35 2.20

4.52 4.80 5.31 4.49 4.76 5.21 4.05 3.99 4.40 3.64 4.34 4.95 4.38 4.36 3.90 4.47 2.32

4.73 4.84 5.46 4.51 5.19 5.54 4.14 4.10 4.44 4.01 4.59 5.15 4.43 4.53 4.03 4.65 2.49

4.85 5.00 5.58 4.70 5.37 5.63 4.34 4.37 4.50 4.28 4.71 5.31 4.50 4.62 4.13 4.79 2.64

4.88 5.12 5.60 4.70 5.55 5.73 4.44 4.38 4.71 4.37 4.89 5.37 4.69 4.75 4.18 4.89 2.74

E3 E2 E1 D3 D2 D1 C3 C2 C1 B3 B2 B1 A3 A2 A1 AVRG = %Rut =

3.65 3.76 4.21 4.70 4.62 4.10 5.72 5.60 5.31 6.66 6.67 6.37 6.39 6.00 5.95 5.31 –

5.67 5.68 6.09 6.88 6.76 6.71 8.49 8.20 7.95 8.69 9.14 8.84 9.06 8.69 9.02 7.72 2.41

6.00 6.02 6.38 7.32 7.33 7.28 9.05 9.03 8.64 9.33 9.95 9.35 9.48 9.57 9.44 8.28 2.96

6.19 6.18 6.53 7.60 7.66 7.57 9.15 9.35 8.93 9.55 10.26 9.76 9.63 9.90 9.63 8.53 3.21

6.42 6.44 6.67 7.91 8.20 7.91 9.25 9.85 9.41 9.63 10.61 10.21 10.03 10.18 9.97 8.85 3.53

6.69 6.96 7.01 8.12 8.59 8.44 9.75 10.47 9.82 10.08 11.32 10.78 10.22 10.66 10.29 9.28 3.97

6.85 7.23 7.25 8.31 9.27 8.93 9.84 10.79 10.20 10.41 11.82 11.24 10.37 10.98 10.65 9.61 4.30

CYCLE = AVRG%RUT =

1000 –

1000 2.06

3000 2.47

5000 2.63

10,000 2.85

30,000 3.06

50,000 3.17

CYCLE = AVRG%RUT =

1000 –

1000 2.42

3000 2.89

5000 3.15

10,000 3.47

30,000 3.92

50,000 4.26

Right sample

Dp = 2421

Right sample

Dp = 2405

764

H. Özen / Construction and Building Materials 25 (2011) 756–765

100 mm, accomplishes a limited lateral pressure, which gives more justice to mixes that get their stability not so much by forces of cohesion but much more so by the inner friction of the aggregate. Trials have shown a much better coefficient of correlation (0.91) with the wheel-tracking test for the modified model (diameter of sample 150 mm and diameter of platen 100 mm) than for the traditional model (0.36) with the same diameter for sample and platen. By evaluating asphalt mixes and pavements from a functional point of view, the possibility to develop better products that better stand up to demands of today and tomorrow will increase. To be able to use demands on functional properties there is however a necessity for functional methods of measurement that fulfill demands on good relevance, high flexibility, and low cost. The first step in the development of functional methods of measurement is to have for certainty samples with a good affinity to real conditions on the road. A study made in Sweden has proven that the traditional Marshall method is not suitable in this regard. The unsuitability of the Marshall method of compaction has also been proven by several other investigators in other countries. A study for alternatives has emphasized the importance of a kneading ingredient in the compaction effort, which is in accordance with methods like rolling wheel and gyratory compactor. The same study showed that a sample compacted in the laboratory, at the same degree of compaction, usually gets better mechanical properties (indirect tensile stiffness modulus, dynamic creep test, and indirect tensile test) than a sample compacted in the field and that the difference between laboratory and field is not the same for different types of mixes [6]. The failure of the Marshall test to describe rutting resistance of asphalt mixes is demonstrated where the Marshall stability is plotted versus the rut depth at 50,000 wheels passes as determined in a laboratory test track experiment. Several conventional and polymer-modified binders were used in the experiments. From these results it is clear that no relation exists between the Marshall stability and rutting under actual wheel loading in the LTT. The Marshall test should therefore not be considered relevant to characterize the resistance of mixes with polymer-modified binders. Fortunately, this fact has nowadays been recognized by authorities who aim to implement rational performance-based

Table 17 LCPC rutting values for real field cylinder compacted 2%lime 5%SBS samples. Left sample

Dp = 2396

Cycle Value N/°C

1000 24 °C

1000 60 °C

3000 60 °C

5000 60 °C

10,000 60 °C

30,000 60 °C

50,000 60 °C

A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3 AVRG = %Rut =

0.92 1.16 1.90 0.35 0.11 0.29 0.27 0.10 0.10 1.01 0.89 0.44 0.57 0.20 0.60 0.59 –

4.45 5.07 4.22 3.75 3.21 2.03 2.52 2.01 1.36 3.00 2.72 2.26 2.39 2.22 2.22 2.90 2.30

5.18 5.06 4.76 4.33 3.36 2.38 3.02 2.46 1.90 3.59 3.21 2.59 2.76 2.98 2.38 3.33 2.74

5.23 5.80 4.80 4.43 3.62 2.67 3.29 2.52 1.99 3.94 3.37 2.73 2.86 3.40 2.41 3.54 2.94

5.49 6.00 5.11 4.67 3.88 2.70 3.67 2.75 2.20 4.19 3.73 2.99 3.06 3.98 2.70 3.81 3.21

5.78 6.25 5.20 4.93 4.15 2.92 3.91 2.92 2.61 4.37 4.14 3.30 3.27 4.27 3.00 4.07 3.47

5.96 6.30 5.32 5.10 4.30 3.06 3.98 3.07 3.00 4.48 4.18 3.37 3.51 4.30 3.10 4.20 3.61

Dp = 2421 2.53 2.18 2.38 2.29 0.20 2.54 2.10 1.49 1.79 2.11 2.41 2.64 2.43 2.44 2.78 2.15 –

4.09 4.28 4.81 3.91 4.23 4.48 3.58 3.51 3.75 3.34 3.81 4.41 4.02 3.99 3.48 3.98 1.83

4.37 4.65 5.23 4.18 4.74 5.17 3.74 3.97 4.34 3.62 4.14 4.62 4.36 4.30 3.87 4.35 2.20

4.52 4.80 5.31 4.49 4.76 5.21 4.05 3.99 4.40 3.64 4.34 4.95 4.38 4.36 3.90 4.47 2.32

4.73 4.84 5.46 4.51 5.19 5.54 4.14 4.10 4.44 4.01 4.59 5.15 4.43 4.53 4.03 4.65 2.49

4.85 5.00 5.58 4.70 5.37 5.63 4.34 4.37 4.50 4.28 4.71 5.31 4.50 4.62 4.13 4.79 2.64

4.88 5.12 5.60 4.70 5.55 5.73 4.44 4.38 4.71 4.37 4.89 5.37 4.69 4.75 4.18 4.89 2.74

CYCLE = AVRG%RUT =

1000 –

1000 2.06

3000 2.47

5000 2.63

10,000 2.85

30,000 3.06

50,000 3.17

5000

150mm creep def.

100mm creep def.

E3 E2 E1 D3 D2 D1 C3 C2 C1 B3 B2 B1 A3 A2 A1 AVRG = %Rut =

4000 3000

2

R = 0,7758

2000 1000 0

8000 6000

R2 = 0,9207

4000 2000 0

0

2

4

6

8

0

2

4

LCPC field roller

6

8

LCPC field roller

100mm creep def.

Fig. 9. Correlation between LCPC field roller and 100 mm and 150 mm samples (freeze and thaw cycling).

8000

150mm creep def.

Right sample

R2 = 0,5983

6000 4000 2000 0

8000 6000

R2 = 0,8836

4000 2000 0

0

2

4

LCPC field roller

6

8

0

2

4

6

LCPC field roller

Fig. 10. Correlation between LCPC field roller and 100 mm and 150 mm samples (water immersed samples).

8

765

5000

150mm creep def.

100mm creep def.

H. Özen / Construction and Building Materials 25 (2011) 756–765

4000 R2 = 0,9176

3000 2000 1000 0

0

1

2

3

4

5

7000 6000 5000 4000 3000 2000 1000 0

6

R2 = 0,805

0

1

LCPC compactor

2

3

4

5

6

LCPC compactor

8000

150mm creep def.

100mm creep def.

Fig. 11. Correlation between LCPC compactor and 100 mm and 150 mm samples (freeze and thaw cycling).

R2 = 0,0529

6000 4000 2000 0

8000 6000 R2 = 0,8017

4000 2000 0

0

1

2

3

4

5

6

0

LCPC compactor

1

2

3

4

5

6

LCPC compactor

Fig. 12. Correlation between LCPC compactor and 100 mm and 150 mm samples (water immersed).

specifications in the SHRP in the USA and in Europe in CEN specifications [17]. 4. Conclusions SBS polymer and lime–SBS modified asphalt mixtures were evaluated in a view of rutting performance. LCPC wheel tracking compaction effort was interrogated with the field roller compaction in LCPC loading system. And also 100 mm and 150 mm samples were prepared and repeated creep tests for these samples were realized. Regression interaction between different samples dimensions and LCPC tests were researched. From these researches it can be concluded: LCPC wheel-tracking test results show that lime–SBS mixtures reveal highest performance according to the other mixtures types. Polymer modification increased rutting resistance of lime modified ones. Both original LCPC compactor and field roller compaction showed resemble results. 150 mm samples showed highest correlation (higher than R2 = 0.80) between LCPC test and repeated creep test for different compaction types and different moisture conditionings. It was shown that LCPC compactor shows good correlation with the real field roller. Field roller compacted samples showed higher permanent deformation than the LCPC compactor. It is thought that higher void contents can be concerned in highway pavements. Laboratory prepared samples for both compacted cylindrically samples (Marshall Compaction) and slabs (wheel tracking compactors) gives higher rut resistance because of the compaction simulation differences.

Acknowledgments This investigation is a part of the research supported by TUBITAK (Project Number: 106M495). The author would like to thank TUBITAK for providing the opportunity to perform this study. Dogus Construction, Ozture Lime, Isfalt Co is also gratefully acknowledged for their laboratory facilities and opportunities. The author is also indebted to Mr. A. Aksoy for assistance.

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