Design and Performance of Anticracking Asphalt-Treated Base.
In China, semirigid inorganic binding material stabilized macadam was used as a base course in 95% of asphalt pavements [1, 2]. The semirigid base course can objectively provide the necessary structural capacity for pavement under heavy traffic condition in our country. However, semirigid base course cracks easily because of its temperature shrinkage and/or dry shrinkage. The cracks in the base course will result in reflection cracks through asphalt pavement surface after being opened to traffic for only 1 or 2 years whether the pavement is in the frozen or unfrozen regions. Then water will penetrate into the pavement structure and will accelerate the destruction process of the pavement [3-5].
A thorough literature review revealed that extensive past research focused on characterizing and assessing ATB through laboratory evaluations [6-11], field investigations and validations [12-14], and empirical and mechanistic modeling [15,16]. Marjerison studied the mechanistic comparison of cement- and bituminous-stabilized granular base systems . Schwartz and Khosravifar studied the design and evaluation of foamed asphalt base materials . Wang put forward a performance-based mixture design of asphalt-treated base . Li et al. studied the materials and temperature effects on the resilient response of asphalt-treated alaskanbase course materials . Hector developed a new mix design method and specification requirements for asphalt-treated bases . Zhang et al. studied the volumetric properties and permeability of asphalt-treated permeable base mixtures . Haider et al. investigate the effects of HMA surface layer thickness, base type, base thickness, and drainage on the performance of new flexible pavements constructed in different site conditions (subgrade type and climate), and the data are from the SPS-1 experiment of the Long-Term Pavement Performance program. Base type was found to be the most critical design factor affecting fatigue cracking, roughness (IRI), and longitudinal cracking (wheel path). The best performance was shown by pavement sections with asphalt-treated bases .
In recent years, a layer of ATB was utilized between the semirigid base course and asphalt concrete layer to avoid or delay the reflective cracks. This is according to the structural and material characteristics of abroad long-lasting asphalt pavement [1-4]. But reflection cracks had not been eliminated fundamentally [3, 4]. The test pavement structure section constructed by Dong et al. demonstrated that ATB can effectively decrease the premature failure caused by reflection cracks . Feng and Hao put forward a five-control-points design method for dense gradation ATB, and the designed gradation was close to the gradation designed through CAVF method . Zhesheng and Qian concluded that ATB has good mechanical and fatigue properties according to fatigue tests results conducted to ATB beams under different stress ratios . Research results of Qian and Shu revealed that ATB with high viscosity hard asphalt (AH30) is superior to the ATB with original asphalt (AH70) in high-temperature stability, water stability, and fatigue life .
So, the aim of this paper is to enhance the crack resistance of ATB. The gradation objective and design method were put forward on the anticracking ATB, which was called GSOG later. The gradation of this new kind of anticracking ATB, GSOG, is partially or completely gapped in middle particle size of coarse aggregates, and its void is 8% to 12%, namely, semiopened. In order to compensate for the weakening of the bonding force between the coarse aggregates due to the increase of voids, SBS modified asphalt was used as the binder. Its gradation design method is based on the volume design method and performance tests. According to this GSOG design method, GSOG-25 was designed, and various performance tests were conducted and compared with the ordinary ATB-25. The tests results demonstrated that the performance of GSOG-25 is great and its antireflection cracking capacity is much better than the ordinary ATB. So, it can be used to prolong the service life of asphalt pavement structure.
2. Gradation Design Method of the Anticracking ATB
2.1. Basic Principles. In order to enhance the crack resistance of ATB, the solutions were put forward from two aspects of gradation and asphalt binder. They are given as follows.
(1) Regarding air voids, the voids in the mixture can eliminate or attenuate the stress concentration and extend the crack propagation path. So, a certain amount of voids can be used to enhance the crack resistance of the mixture. The mixture gradation can be designed as a semiopened gradation; namely, its void content is 8% to 12%.
(2) As regards gradation, skeleton structure formed by squeezing of coarse aggregate can enhance the bearing capacity. So, coarse aggregates in the GSOG gradation should squeeze each other to form a stable skeleton to withstand the external load and maintain the stability of the material structure and enhance its high-temperature stability and deformation resistance [28, 29]. To avoid the interference caused by the middle particle size to the coarse aggregate skeleton structure and ensure the stability of the coarse aggregate skeleton structure, the intermediate particle sizes (4.75 mm and/or 9.5 mm) coarse aggregates were completely or partially gapped .
(3) For asphalt binder, considering that increasing porosity of the mixture will affect the bond between aggregates and will affect the performance and durability of the mixture, polymer modified asphalt can be used as the asphalt binder. The use of polymer modified asphalt can not only enhance the cohesion between aggregates but also increase the thickness of asphalt film and enhance its fatigue and cracking resistance. This will improve its durability.
(4) Concerning performance, the performances of designed GSOG, including high-temperature stability, low-temperature crack resistance, water stability, fatigue resistance, and crack resistance, should meet the requirements or be better than the ordinary ATB.
2.2. Basis Procedures. According to the upper basic design principles, a gradation optimization method was put forward based on the volume design method  and performance tests. Its basic steps are given as follows.
(1) Several gradations with the intermediate particle sizes (4.75 mm and/or 9.5 mm) coarse aggregates gapped completely or partially were initially designed according to the gradation limits of ATB.
(2) The void of coarse aggregate, VCA, was determined through the dry-rodded compaction tests of coarse aggregates.
VCA = ([[1 - [GCA.sub.DRC]]/[G.sub.b,ca]]), (1)
where VCA is the void of dry-rodded compacted coarse aggregates, %; [GCA.sub.DRC] is the dry-rodded compacted density of coarse aggregates, g x [cm.sup.-3]; and [G.sub.b,ca] is the bulk density of coarse aggregates, g x [cm.sup.-3].
(3) Calculate the air voids of each mixture at different asphalt aggregate ratio according to their gradations and densities of each aggregate.
[V.sub.a] = VCA - [[[P.sub.fa]/[G.sub.b,fa] + [P.sub.fi]/[G.sub.a,fi] + [P.sub.b]/[G.sub.b]]/[P.sub.ca]/[GCA.sub.DRC]], (2)
where [V.sub.a] is the air void of asphalt mixture, %; [P.sub.b] is the asphalt aggregate ratio, %; [G.sub.b,fa] is the bulk density of fine aggregates, g x [cm.sup.-3]; [G.sub.a,fi] is the apparent density of filler, g x [cm.sup.- 3]; [G.sub.b] is the density of asphalt, g x [cm.sup.-3] ; [P.sub.ca] is the mass fraction of coarse aggregate to all aggregates, %; [P.sub.fa] is the mass fraction of fine aggregate to all aggregates, %; and [P.sub.fi] is the mass fraction of filler (<0.075 mm) to all aggregates, %.
(4) Fabricate samples with Superpave Gyratory Compactor (SGC) for those gradations whose voids meet the requirements. Vacuum seal the samples with CoreLok, and then measure their bulk densities and air voids using Immersion Weighting method.
(5) Select the gradations whose air voids meet the requirements to fabricate different types of samples for different performance tests, including high-temperature stability, water stability, and fatigue resistance. Finally, the gradation whose performance is the best was selected as the optimal gradation.
3. Raw Materials
3.1. Asphalt Binders. Two kinds of asphalt binder were used in this paper: Shell 70-A original asphalt and SBS modified asphalt binder. Shell 70-A was used in the ordinary ATB-25 as the contrast material, and the SBS modified asphalt binder was used in the new designed GSOG-25. Their technical indexes were presented in Table 1.
3.2. Aggregate. The coarse aggregates, fine aggregates, and filler were produced from limestone. Their technical indexes were shown in Tables 2, 3, and 4.
4. Proportion Design of GSOG-25 Mixtures
4.1. Initially Designed Gradations. Through controlling the passage percent of aggregates of the four key sizes, 26.5 mm, 9.5 mm, 4.75 mm, 0.075 mm sieves, and partially gapping the usage of aggregates passing sieve size of 4.75 mm and/or 9.5 mm, 5 different gradations were designed initially according to Chinese Technical Specification for Construction of Highway Asphalt Pavement , as shown in Table 5.
In Table 5, gradations 1, 3, and 4 were partially gapped at the particle size of 4.75 mm, and gradations 2 and 5 were partially gapped at the particle size of 9.5 mm.
4.2. Measuring the Void of Coarse Aggregate, VCA, for Each Gradation. Dry-rodded compaction was conducted on coarse aggregates ([greater than or equal to] 4.75 mm) for each gradation, and their VCA were calculated, as shown in Table 6.
4.3. Calculating the Theoretical Voids of Each Gradation. The asphalt aggregate ratio of the mixture was estimated at 4.2%, and the corresponding theoretical void of each gradation was calculated, as shown in Table 7.
From Table 7, it can be seen that the air voids of gradations 2, 4, and 5 meet the requirement. So, they were selected for further research.
4.4. The Air Voids of Fabricated Samples. For gradations 2, 4, and 5, cylinder samples were fabricated at the asphalt aggregate ratio of 4.2% using SGC. The compaction parameters of SGC were the following: compaction times, 174 times, vertical pressure, 600 KPa, and compactor angle, 1.16[degrees].
The samples were vacuum sealed with CoreLok, and then their bulk density and voids were measured with Immersion Weighting method, as shown in Table 8.
It can be seen from Table 8 that the air voids of gradation 2 were very smaller than the requirement, and those of gradations 4 and 5 meet the requirements. So, gradations 4 and 5 were selected for further optimization.
4.5. Performance Tests. In order to enhance crack resistance, the asphalt aggregate ratio should be higher than ordinary ATB mixture. So, three asphalt aggregate ratios, 3.9%, 4.2%, and 4.5%, were selected to fabricate GSOG-25 samples for both gradations (gradations 4 and 5).
The SGC cylinder samples' air voids were shown in Table 9.
(1) Moisture Susceptibility and High-Temperature Stability. High-Temperature Immersion Wheel Truck Test of Asphalt Mixtures can be used to measure the water stability and high-temperature stability of the asphalt mixture. So, the Immersion Wheel Truck Test at 60[degrees] C with Hamburg rutting tester was selected. The size of plate sample is 300 mm x 300 mm x 80 mm, the samples were immersed into water at 60[degrees]C for 2 hours, and then the test was started. The tests were set to end when loading 30000 times or when rut depth arrived at 20 mm. The results were shown in Table 10.
(2) Fatigue Resistance. Four-point bending fatigue test was selected to evaluate the fatigue resistance of GSOG-25 beam sample. The size of the sample is 300 mm x 60 mm x 80 mm. Because the aim of the tests is to compare the fatigue resistance of different gradation with different asphalt aggregate ratio, the fatigue loading parameters were the same: test temperature is 20[degrees]C, loading waveform is sinusoidal wave, loading frequency f = 10 Hz, and the cyclic Eigen value [rho] = [P.sub.min]/[P.sub.max] = 0.3 KN/3 KN = 0.1. The fatigue results were shown in Table 11.
(3) Seepage. Seepage performance was measured on plate sample according to Chinese standard test methods of bitumen and bituminous mixtures for highway engineering . The results were shown in Table 12.
4.6. Selection of Optimal Gradation. It can be seen from Table 6 that gradation 5 with 4.2% asphalt aggregate ratio has the best high-temperature stability and water stability, and gradation 4 with 4.5% asphalt aggregate ratio has the best fatigue resistance. Considering that the project is located in south China, the climate is characterized by high temperature and is rainy, so gradation 5 with 4.2% asphalt aggregate ratio was selected as the optimal gradation.
5. Comparison of the Performances
The performance, especially the antireflection cracking resistance of the optimized GSOG-25, was measured and compared with those of the ordinary ATB-25.
5.1. Design of the Ordinary ATB-25. The gradation of ATB-25 was designed according to Chinese Technical Specification for Construction of Highway Asphalt Pavement (JTG F40-2004) , the asphalt binder is Shell 70-A, and optimal asphalt content is 3.7%. Its gradation was shown in Table 13.
The Marshall technological indexes of the ordinary ATB-25 were shown in Table 14.
5.2. Comparison of the Performances. The performance properties of asphalt mixture include resistance to hightemperature deformation, to low-temperature cracking, to water damage, and to fatigue cracking. Considering that the ATB course usually lies 16 cm to 20 cm below the pavement surface, the low-temperature performance was not concerned in the paper. The compared performances include resistance to high-temperature deformation, to water damage, to fatigue cracking, and to antireflection crack.
(1) Resistance to High-Temperature Deformation. The rutting tests at 60[degrees]C were conducted to evaluate their high-temperature stability. The sample size is 300 mm x 300 mm x 80 mm, compacted with kneading compactor. According to Chinese standard test methods of bitumen and bituminous mixtures (JTG E20-2011) , the dynamic stability index, DS, was used as the evaluation index.
DS = [[[d.sub.2] - [d.sub.1]]/[[t.sub.2] - [t.sub.1]]], (3)
where DS is dynamic stability, times/mm; [d.sub.2] is deformation at the moment of [t.sub.2], mm; and [d.sub.1] is deformation at the moment of [t.sub.1], mm.
The results were shown in Table 15.
It can be seen from Table 15 that the dynamic stability of GSOG-25 is obviously higher than that of ATB-25, and the rut depth of GSOG-25 is only about half of that of ATB-25. So the resistance to high-temperature deformation of GSOG-25 is obviously better than that of ATB-25.
(2) Water Stability. The residual Marshall stability, S, is used as the index to evaluate the water stability according to the Chinese Technical Specification for Construction of Highway Asphalt Pavement.
Standard Marshall test and immersion Marshall test were conducted according to Chinese standard test methods of bitumen and bituminous mixtures for highway engineering, T0709-2011 , and then the residual stability, S, can be determined from the Marshall stability [S.sub.0] and the immersion Marshall stability [S.sub.1] according to formula (4).
S = [[S.sub.1]/[S.sub.0]] x 100%, (4)
where S is the residual stability, %; [S.sub.1] is the immersion Marshall stability, kN; and [S.sub.0] is the Marshall stability, kN.
The results of water stability tests were shown in Table 16.
It can be seen from Table 16 that the water stability of these two designed mixtures meets the specification requirement. And the residual stability of GSOG-25 is greater than that of ATB-25, which means that the water stability of GSOG-25 is better than that of ATB-25.
(3) Fatigue Resistance. Four-point bending fatigue tests were conducted with servo material tester, UTM-100, to compare the fatigue performance of the two designed mixtures.
The size of the beam samples is 380 mm x 60 mm x 50 mm. The samples were formed by using a vibration roller, HYLN-5, through a pneumatic loading, and it is a good simulation to the site situation of asphalt pavement. The test temperature is 15 [+ or -] 0.5[degrees]C and loading frequency is 10 [+ or -] 0.1 Hz according to Chinese standard test methods of bitumen and bituminous mixtures for highway engineering . The maximum strain was controlled during the repeated loading, and the [N.sub.f50] method was used to determine the fatigue life, which means that when the modulus of the sample is decreased to 50% of its initial modulus, the cyclic loading times are its fatigue life. The results were given in Table 17 and were contrasted in Figure 1.
It can be seen from Table 17 and Figure 1 that the fatigue performance of GSOG-25 is much better than that of ATB-25 obviously. When the maximum strain is controlled at 400 ^e, the fatigue life of GSOG-25 is about 220 times greater than that of the ordinary ATB-25. And when the strain level is controlled at 600 [mu][epsilon], the fatigue life of GSOG-25 is also much greater than that of the ordinary ATB-25.
(4) Antireflection Cracking Resistance. Loading mode of reflection crack resistance test shown in Figure 2 was used to measure the resistance to reflection cracking.
The sample is a compound sample, which is compounded with ATB layer, cement concrete layer (with a prefabricated crack), and rubber pad. The dimensions of compound sample are as follows: 30 cm (length) x 6 cm (width) x 20 cm (thickness). The thickness of the compound sample is consisting of 8 cm ATB layer, 10 cm cement concrete, and 2 cm rubber pad. The width of the prefabricated crack is 1 cm. The rubber pad is used to simulate the subgrade, and the cement concrete bricks were used to simulate cracked semirigid base course. The loading pad is 2 cm x 6 cm, and the vertical pressure is 0.7 MPa.
The loading mode has two different modes, symmetrical loading for simulate flexural tensile reflection cracking and loading at the edge of one side of prefabricated crack for simulate shear reflection cracking.
The cracking test results of ATB-25 and GSOG-25 at different loading modes were shown in Tables 18 and 19.
It can be seen from Tables 18 and 19 that the optimized GSOG-25 has better reflection crack resistance than ordinary ATB-25. Their initial crack loading cycles are almost the same, but the total life of GSOG-25 is much greater than that of ATB-25.
In order to improve the reflection crack resistance of ATB, the requirements of the mixture and gradation characteristics were put forward, and the gradation design procedures were put forward based on the volume design method and performances tests. And a type of GSOG-25 mixture was optimized according to the design procedures. Comprehensive performance tests, including rutting test, water stability test, fatigue test, and reflection crack test, were conducted on the ordinary ATB-25 and the optimized GSOG-25. The results indicated that the performance of GSOG-25 is superior to ATB-25; its reflection crack resistance has been enhanced much, which meets the purpose of the paper.
Conflicts of Interest
The authors declare that there are no conflicts of interest regarding the publication of this paper.
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Xiaoge Tian, (1) Haifeng Han, (2) Qisen Zhang, (1) Xinwei Li, (2) and Ye Li (1)
(1) Changsha University of Science & Technology, Changsha, Hunan 410114, China
(2) Guangzhou Highway Co. Ltd., Guangzhou, Guangdong 760000, China
Correspondence should be addressed to Xiaoge Tian; email@example.com
Received 28 February 2017; Accepted 12 April 2017; Published 22 May 2017
Academic Editor: Hainian Wang
Caption: Figure 1: Comparison of fatigue lives of the two mixtures.
Caption: Figure 2: Reflection crack resistance test loading mode.
Table 1: Technical indexes of asphalt binders. Technical indexes Unit Shell 70-A Penetration (25[degrees]C, 5 s, 100 g) 0.1 mm 67 Softening point, R&B [degrees]C 47.5 Kinematic viscosity @177[degrees]C Pa x s -- Kinetic viscosity @60[degrees]C Pa x s 223 Flash point [degrees]C 327 Elastic recovery @25[degrees]C % -- Difference of softening point for 48 h [degrees]C -- Mass lost % 0.10 Penetration ratio, 25[degrees] C % 65.2 Technical indexes SBS modified asphalt Penetration (25[degrees]C, 5 s, 100 g) 46 Softening point, R&B 73 Kinematic viscosity @177[degrees]C 2.0 Kinetic viscosity @60[degrees]C -- Flash point 230 Elastic recovery @25[degrees]C 83 Difference of softening point for 48 h 2.0 Mass lost 0.12 Penetration ratio, 25[degrees] C 79 Table 2: Technical indexes of coarse aggregates. Index Unit Actual measurement Crushing value % 13.5 Apparent relative density -- -- Water absorption % 1.2 Strength % 9.4 Needle and plate particle content % 8 Content of <0.075 mm material % 0.43 Adhesion with SBS modified asphalt Level 5 Table 3: Densities of aggregates. Particle size (mm) Apparent relative Bulk volume relative density density (g/[cm.sup.3]) 26.5 2.783 2.770 19 2.731 2.716 16 2.745 2.734 13.2 2.717 2.693 9.5 2.736 2.723 4.75 2.696 2.618 2.36 2.755 2.720 1.18 2.742 2.695 0.6 2.739 2.676 0.3 2.759 2.707 0.15 2.711 2.672 0.075 2.654 2.609 Table 4: Technical indexes of filler. Project Unit Test result Apparent density t/[m.sup.3] 2.640 Water content % 0.41 Particle size range <0.6 mm % 100 <0.15 mm % 94.5 <0.075 mm % 83 Appearance -- No clustering Hydrophilic index -- 0.6 Plasticity index -- 3 Project Specification requirements Apparent density [greater than or equal to] 2.50 Water content <1 Particle size range <0.6 mm 100 <0.15 mm 90~100 <0.075 mm 75~100 Appearance No clustering Hydrophilic index <1 Plasticity index <4 Table 5: Initially designed gradations. Sieve sizes 31.5 26.5 19 16 13.2 9.5 4.75 (mm) Gradation 1 (%) 100 77 58.8 49.1 39.5 18.5 17.8 Gradation 2 (%) 100 77 55.8 49.1 28.5 27.5 17.8 Gradation 3 (%) 100 100 67.4 51.9 37.3 19.4 17.5 Gradation 4 (%) 100 75.7 56.2 45.2 34.3 21 19.8 Gradation 5 (%) 100 75.2 55.2 43.7 32.3 30.5 17.8 Sieve sizes 2.36 1.18 0.6 0.3 0.15 0.075 (mm) Gradation 1 (%) 15 12 8 5.5 4.8 3.3 Gradation 2 (%) 15 12 8 5.5 4.8 3.3 Gradation 3 (%) 13.6 10.7 8.4 6.5 5.1 4 Gradation 4 (%) 15 12 8 5.5 4.8 3.3 Gradation 5 (%) 15 12 8 5.5 4.8 3.3 Table 6: The VCA of each gradation. Gradation Density at dry-rodded Bulk density ofcoarse VCA compaction aggregates (%) (g x [cm.sup.-3]) (g x [cm.sup.-3]) Gradation 1 1.942 2.747 29.32 Gradation 2 1.916 2.739 30.05 Gradation 3 1.863 2.721 31.5 Gradation 4 1.829 2.735 33.1 Gradation 5 1.864 2.729 31.7 Table 7: Theoretical void of each gradation. Estimated asphalt Gradation aggregate ratio Theoretical void (%) (%) Gradation 1 4.2 5.7 Gradation 2 4.2 9.5 Gradation 3 4.2 6.7 Gradation 4 4.2 12.4 Gradation 5 4.2 12.1 Table 8: Measured air voids of each gradation at asphalt aggregate ratio of 4.2%. Gradation Bulk density Theoretical maximum Void Average (g x [cm.sup.-3]) relative density (%) void (g x [cm.sup.-3]) (%) Gradation 2 2.379 2.561 7.1 6.8 3.386 2.561 6.8 Gradation 4 2.344 2.558 8.4 8.1 2.358 2.558 7.8 Gradation 5 2.353 2.554 7.9 8.0 2.348 2.554 8.1 Table 9: Measured voids of ATB mixtures. Gradation Asphalt aggregate ratio Voids (%) (%) Sample 1 Sample 2 Average 3.9 9.7 9.1 9.4 Gradation 4 4.2 8.4 7.8 8.1 4.5 7.0 7.6 7.3 3.9 9.5 9.0 9.2 Gradation 5 4.2 7.9 8.1 8.0 4.5 7.4 6.7 7.1 Table 10: Hamburg immersion rutting test results. Gradation Asphalt aggregate ratio Times Depth of rut (%) (mm) Gradation 4 3.9 20900 20 4.2 30000 14.33 4.5 30000 12.78 Gradation 5 3.9 30000 12.06 4.2 30000 7.96 4.5 30000 11.22 Table 11: Fatigue results. Gradation Asphalt Fatigue life (cycles) aggregate ratio (%) Sample 1 Sample 2 Sample 3 Average Gradation 4 3.9 527 655 763 648 4.2 2289 1739 788 1605 4.5 3707 4344 1867 3306 Gradation 5 3.9 807 1012 711 843 4.2 1703 1309 1072 1361 4.5 1925 2090 1884 1966 Table 12: Permeability coefficient and voids of specimens. Gradation Asphalt aggregate ratio Permeability coefficient Void (%) (ml/min) (%) Gradation 4 3.9 420 9.8 4.2 145 9.0 4.5 No seepage 8.3 Gradation 5 3.9 380 9.6 4.2 135 8.7 4.5 No seepage 8.0 Table 13: Gradation of ATB-25. Size of sieve 31.5 26.5 19 16 13.2 9.5 4.75 (mm) Upper limit 100 100 90 76 62 52 40 Lower limit 100 90 70 55 42 32 20 Gradation 100 93.5 80.5 65.8 52.0 40.1 29.3 Size of sieve 2.36 1.18 0.6 0.3 0.15 0.075 (mm) Upper limit 29 25 18 14 10 6 Lower limit 14 10 8 5 3 2 Gradation 20.5 15.6 11.8 8.3 6.3 3.8 Table 14: Marshall technological index of ATB-25. Technological index Bulk density Theoretical void VCA (g x [cm.sup.-3]) max. density (%) (%) (g x [cm.sup.-3]) 2.447 2.571 3.6 12.0 Technological index Bulk density Asphalt saturation Stability Flow value (g x [cm.sup.-3]) (%) (KN) (mm) 2.447 69.6 3.10 3.1 Table 15: Rutting test results. Index [d.sub.1] [d.sub.2] DS Average (mm) (mm) (cycles/mm) (cycles/mm) GSOG-25 1 2.189 2.363 3620 3320 2 2.283 2.499 3020 ATB-25 1 4.710 5.263 1139 1097 2 4.825 5.423 1054 Table 16: Residual stability of different mixtures. Mixture Marshall stability Immersion stability Residual stability (kN) (kN) (%) ATB-25 3.10 2.74 88.4 GSOG-25 8.13 8.05 99.0 Table 17: Fatigue lives of different mixtures. Index Strain level Initial modulus Fatigue life Average value ([mu][epsilon]) (MPa) (cycles) (cycles) GSOG-25 400 4676 467090 441465 4568 415840 600 5032 154920 162015 ATB-25 4088 169110 400 6577 21010 23385 3952 25760 600 7453 3030 3305 Table 18: Flexural tensile type reflection crack. Mixture Sample Initial crack Total life (x [10.sup.4] cycles) (x [10.sup.4] cycles) ATB-25 1 0.56 14.6 2 0.74 18.6 3 0.68 15.9 4 0.54 15.1 GSOG-25 1 0.68 26.3 2 0.90 31.1 3 0.45 10.6 4 0.78 27.5 Mixture Sample Average (x [10.sup.4] cycles) Initial crack Total life ATB-25 1 0.63 16.05 2 3 4 GSOG-25 1 0.7 28.3 2 3 4 Table 19: Shearing type reflection crack. Mixture Sample Initial crack Total life (x [10.sup.4] cycles) (x [10.sup.4] cycles) ATB-25 1 0.62 15.8 2 0.45 9.4 3 0.56 11.5 4 0.58 13.1 GSOG-25 1 0.9 21.1 2 0.78 24.2 3 0.72 19.4 4 0.66 17.9 Mixture Sample Average (x [10.sup.4] cycles) Initial crack Total life ATB-25 1 0.55 12.45 2 3 4 GSOG-25 1 0.77 20.7 2 3 4
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|Title Annotation:||Research Article|
|Author:||Tian, Xiaoge; Han, Haifeng; Zhang, Qisen; Li, Xinwei; Li, Ye|
|Publication:||Advances in Materials Science and Engineering|
|Date:||Jan 1, 2017|
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