Preliminary prediction of endurance limit for asphalt rubber mixtures due to healing

2014 ◽  
Vol 41 (11) ◽  
pp. 964-969 ◽  
Author(s):  
Mena I. Souliman ◽  
Michael Mamlouk ◽  
Kamil E. Kaloush
Keyword(s):  
Endurance Limit ◽  
Test Procedure ◽  
Rest Period ◽  
Fatigue Cracking ◽  
Asphalt Mixtures ◽  
Stiffness Ratio ◽  
Rubber Mixture ◽  
Limit Values ◽  
Economic Implications ◽  
Asphalt Rubber

One of the main requirements of designing perpetual pavements is to determine the endurance limit of asphalt mixtures. The endurance limit is the strain below which no fatigue damage occurs or can be healed during unloading. If the pavement thickness is controlled so that the strain at the bottom of the asphalt layer is kept below the endurance limit, the pavement would endure indefinite load repetitions and would not experience bottom-up fatigue cracking. Field observation shows that an endurance limit for hot mix asphalt (HMA) does exist. The endurance limit values were previously determined in the laboratory in the NCHRP Project 9-44A for conventional HMA at different conditions. The purpose of this paper was to determine the endurance limit values for asphalt rubber (AR) mixtures using laboratory beam fatigue tests. The paper discusses the results of a study that produced a preliminary estimation of the endurance limit for an asphalt rubber mixture placed in Sweden. This study included 24 beam fatigue laboratory tests conducted according to the AASHTO T321-03 test procedure with rest periods between loading cycles. Two factors that affect the fatigue response of asphalt mixtures were evaluated, which are the applied strain and the rest period between loading cycles. A model was developed to determine the stiffness ratio as a function of strain and rest period. The endurance limit was determined using the developed model by setting the stiffness ratio as one, indicating no accumulated damage or complete healing. Endurance limit values for the AR mixture ranged from 150 to 175 microstrain at 20 °C, which are significantly higher than those of conventional HMA. This indicates that a thinner asphalt rubber layer can be used to reach the endurance limit as compared to the HMA layer. Determining the endurance limit of asphalt rubber has significant design and economic implications.

scholarly journals Performance Evaluation of Asphalt Rubber Mixture with Additives

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1200 ◽  
Author(s):  
Cheng ◽  
Liu ◽  
Ren ◽  
Huang
Keyword(s):  
High Temperature ◽  
Fatigue Cracking ◽  
Crumb Rubber ◽  
Good Choice ◽  
Environmental Benefits ◽  
Fatigue Properties ◽  
Control Group ◽  
Rubber Mixture ◽  
Asphalt Rubber ◽  
Temperature Performance

Crumb rubber, as a recycled material used in asphalt mixture, has gained more attention in recent years due to environmental benefits and the advantages of its pavement, such as excellent resistance to cracking, improved durability, less road maintenance, lower road noise, etc. However, the high-temperature performance of mixture with crumb rubber does not perform well. In order to improve the performance, this paper examined the effect of additives on the laboratory performance of asphalt rubber Stone Matrix Asphalt (AR-SMA) with additives. Three groups of AR-SMA: no additives, Styrene–Butadiene–Styrene (SBS) and Granular Polymer Durable additive (GPDa) were included, with no additives as a control group. Each group was investigated at three asphalt rubber content (ARC): 6.4%, 6.9%, 7.4% with regard to high-temperature and fatigue properties. The results show that with increasing ARC, the high-temperature performance of mixture without additive decreases, and the high-temperature performance increases first and then decreases for SBS and GPDa. Moreover, the rutting resistance of AR-SMA with GPDa at 6.9% ARC performs best. Under the condition of mixtures with appropriate ARC, AR-SMA with GPDa has higher fatigue life and sensitivity to fatigue cracking than the control group. Simultaneously, the fatigue performance of AR-SMA with GPDa is not as significant as that without additive with increasing ARC. In a word, GPDa is a good choice to improve the performance of AR-SMA. However, it should be noted that optimal asphalt content of AR-SMA mixtures with GPDa is higher than that of traditional mixtures.

Use of Superpave Technology for Design and Construction of Rubberized Asphalt Mixtures

1997 ◽  
Vol 1583 (1) ◽  
pp. 71-81 ◽  
Author(s):  
H. Barry Takallou ◽  
Hussain U. Bahia ◽  
Dario Perdomo ◽  
Robert Schwartz
Keyword(s):  
Fatigue Behavior ◽  
Permanent Deformation ◽  
Performance Testing ◽  
Fatigue Cracking ◽  
Asphalt Mixtures ◽  
Mix Design ◽  
Asphalt Rubber ◽  
Constant Height ◽  
Overlay Design ◽  
Gyratory Compaction

The effect of different mixing times and mixing temperatures on the performance of asphalt-rubber binder was evaluated. Four different types of asphalt-rubber binders and neat asphalt were characterized using the Strategic Highway Research Program (SHRP) binder method tests. Subsequently, mix designs were carried out using both the SHRP Levels I and II mix design procedures, as well as the traditional Marshall mix design scheme. Additionally, performance testing was carried out on the mixtures using the Superpave repetitive simple shear test at constant height (RSST-CH) to evaluate the resistance to permanent deformation (rutting) of the rubberized asphalt mixtures. Also, six rectangular beams were subjected to repeated bending in the fatigue tester at different microstrain levels to establish rubberized asphalt mixtures’ resistance to fatigue cracking under repeated loadings. The results indicate that the Superpave mix design produced asphalt-rubber contents that are significantly higher than values used successfully in the field. Marshall-used gyratory compaction could not produce the same densification trends. Superpave mixture analysis testing (Level II) was used successfully for rubberized asphalt mixtures. Results clearly indicated that the mixture selected exhibited acceptable rutting and fatigue behavior for typical new construction and for overlay design. Few problems were encountered in running the Superpave models. The results of the RSST-CH indicate that rubber-modified asphalt concrete meets the criteria for a maximum rut depth of 0.5 in.; and more consistent results were measured for fatigue performance analysis using the repeated four-point bending beam testing (Superpave optional torture testing). The cycles to failure were approximately 26,000 at 600 microstrain.

Design and Evaluation of Asphalt Mixtures for Stress Absorbing Pavement Layers

2015 ◽  
Vol 764-765 ◽  
pp. 116-121
Author(s):  
Ondrej Dasek ◽  
Pavel Coufalik ◽  
Petr Hyzl ◽  
Jan Kudrna ◽  
Jaroslava Daskova ◽  
...  
Keyword(s):  
Low Temperature ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Fatigue Properties ◽  
Rubber Mixture ◽  
Stiffness Modulus ◽  
Theoretical Part ◽  
Asphalt Rubber ◽  
Absorbing Layer ◽  
Tensile Relaxation

This paper deals with the use of special asphalt-rubber mixture, the Stress Absorbing Layer (SAL). Description of SAL and test methods is given in theoretical part of this paper. Several different mixtures were designed and selected ones subsequently tested. Low-temperature properties, rutting test, bending tensile relaxation, stiffness modulus and fatigue properties were determined. These parameters are stated for asphalt-rubber mixtures with aggregate sizes up to 5 mm, 8 mm or 16 mm.

Incorporation of Endurance Limit in the Mechanistic-Empirical Flexible Perpetual Pavement Design

2018 ◽  
Vol 2672 (40) ◽  
pp. 108-121 ◽  
Author(s):  
Sheng Hu ◽  
Sang-Ick Lee ◽  
Lubinda F. Walubita ◽  
Fujie Zhou ◽  
Tom Scullion
Keyword(s):  
Endurance Limit ◽  
Design Method ◽  
Field Performance ◽  
Fatigue Cracking ◽  
Climatic Conditions ◽  
Influential Factors ◽  
Pavement Design ◽  
Design System ◽  
Viscoelastic Continuum Damage ◽  
Perpetual Pavement

In recent years, there has been a push toward designing long-lasting thick hot mix asphalt (HMA) pavements, commonly referred to as a perpetual pavements (PP). For these pavements, it is expected that bottom-up fatigue cracking does not occur if the strain level is below a certain limit that is called the HMA fatigue endurance limit (EL). This paper proposed a mechanistic-empirical PP design method based on this EL concept. The ELs of 12 HMA mixtures were determined using simplified viscoelastic continuum damage testing and the influential factors were comparatively investigated. It was found that HMA mixtures seem to have different EL values based on mix type and test temperatures. There is not just a single EL value that can be used for all mixtures. Thus, default EL criteria for different mixtures under different climatic conditions were developed and incorporated into the Texas Mechanistic-Empirical Flexible Pavement Design System (TxME). As a demonstration and case study, one Texas PP test section with weigh-in-motion traffic data was simulated by TxME. The corresponding TxME inputs/outputs in terms of the PP structure, material properties, traffic loading, environmental conditions, and ELs were demonstrated. The corresponding TxME modeling results were consistent with the actual observed field performance of the in-service PP section.

Estimating Results of a Proposed Simple Performance Test for Hot-Mix Asphalt from Superpave Gyratory Compactor Results

2005 ◽  
Vol 1929 (1) ◽  
pp. 104-113 ◽  
Author(s):  
Ahmed F. Faheem ◽  
Hussain U. Bahia ◽  
Hossein Ajideh
Keyword(s):  
Performance Test ◽  
Test Procedure ◽  
Asphalt Mixtures ◽  
Strongly Correlated ◽  
Flow Number ◽  
Traffic Loading ◽  
Superpave Gyratory Compactor ◽  
The Stability ◽  
Work Done ◽  
Pavement Service Life

This study intended to use the Superpave® gyratory compactor (SGC) as a basis for estimating the stability of asphalt mixtures as a surrogate for proposed method for the simple performance test. Several asphalt mixtures were produced with varying aggregate sources, asphalt contents, and gradations. Every mixture was compacted with the SGC and evaluated with the repeated compression test procedure for rutting measurements recommended by NCHRP Project 9–19 and the AASHTO 2002 pavement design manual to evaluate whether the results from the SGC can be related to the rutting of mixtures. Densification curves produced by the SGC were used to determine the volumetric properties besides the calculation of the traffic densification index (TDI), which represents the densification experienced by traffic loading during pavement service life. The traffic force index (TFI) was also calculated with a special accessory added to the SGC during compaction (the pressure distributor analyzer). The TFI represents the work done by the traffic to densify the mixture. Results from the mixture rutting tests were used to estimate the flow number (FN). The FN, an important mixture property, is shown to have a strong correlation to the TFI. The TFI was also found to be strongly correlated with the TDI and gives an opportunity to estimate the mixture resistance to compaction forces with the use of its volumetric behavior. The main finding of the study is that the SGC appears to give information that can be used to characterize the stability of the mixtures. Such information could be used as an initial screening criterion to select mixtures for various traffic levels.

Damage and Thixotropy in Asphalt Mixture and Binder Fatigue Tests

2012 ◽  
Vol 2293 (1) ◽  
pp. 8-17 ◽  
Author(s):  
Félix Pérez-Jiménez ◽  
Ramon Botella ◽  
Rodrigo Miró
Keyword(s):  
Cyclic Loading ◽  
Strain Amplitude ◽  
Fatigue Testing ◽  
Complex Modulus ◽  
Asphalt Mixture ◽  
Viscoelastic Behavior ◽  
Fatigue Cracking ◽  
Asphalt Mixtures ◽  
Asphalt Binders ◽  
Irreversible Damage

Fatigue cracking is considered one of the main damage mechanisms in asphalt pavement design. Design methods use fatigue laws obtained by laboratory testing of the materials involved. Typically, these tests consist of subjecting the asphalt mixture to cyclic loading until failure occurs. However, failure is associated not with specimen fracture (which is unusual), but with a slight decrease in the mechanical properties of the material, usually in the complex modulus. As a consequence, it is important to differentiate between real damage to the material and changes in its viscoelastic behavior and thixotropy. It is also crucial to account for the healing that occurs in asphalt material after rest periods. The above considerations are important in the fatigue testing of asphalt binders because these materials show pronounced viscoelastic behavior and thixotropy, especially when subjected to cyclic loading. This paper demonstrates that in many cases what is taken for fatigue failure during testing (i.e., a decrease in the complex modulus below half of its initial value) is actually thixotropy. Thus, the complex modulus can be recovered by reducing the loading or, as in this study, the strain applied. In contrast, asphalt mixtures experience irreversible damage, and depending on the asphalt binder, the thixotropic effects are more or less pronounced. This paper analyzes the failure criteria currently used in the fatigue testing of asphalt mixtures and binders and evaluates the parameters chosen, namely, complex modulus (G*) and phase angle (δ) to characterize asphalt binders (G*sin δ). A cyclic uniaxial tension–compression test under strain-controlled conditions was performed. Three test modalities were used: time sweeps (constant strain amplitude until total failure), increasing strain sweeps (increase in strain amplitude every 5,000 cycles), and up-and-down strain sweeps (alternating increases and decreases in strain amplitude).

The Processing and Fatigue Characterization of TiNi and Ti-6Al-4V Porous Materials

2011 ◽  
Vol 493-494 ◽  
pp. 930-935 ◽  
Author(s):  
Emin Erkan Aşik ◽  
Gül Ipek Nakaş ◽  
Şakir Bor
Keyword(s):  
Titanium Alloys ◽  
Endurance Limit ◽  
Fatigue Behavior ◽  
Porous Titanium ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Compression Tests ◽  
Limit Values ◽  
Porous Ti ◽  
Structural Applications

Porous titanium alloys have been extensively studied in biomedical applications due to their elastic moduli similar to that of bone compared to other implant materials. Accordingly, TiNi and Ti-6Al-4V foams have been widely characterized in terms of their various mechanical properties; however, their fatigue properties have not been well studied, even though, it has a vital importance in structural applications such as medical implants. In this study, porous titanium alloys were processed via sintering at 1200 °C for 2 hours employing Mg space holder technique. TiNi and Ti-6Al-4V alloys with a porosity of 49 and 51 vol.%, respectively, were mechanically characterized by monotonic and cyclic compression tests. The compressive strength was determined to be 148 MPa for TiNi foams whereas 172 MPa for Ti-6Al-4V foams with homogenously distributed pores having diameters in the range of 250-600 µm. Endurance limit values were determined relative to the yield strength of each porous alloy in order to enable the comparison of fatigue behavior. The fatigue tests applied with a frequency of 5 Hz and a constant stress ratio (σmin/σmax) of 0.1 have revealed that porous TiNi alloys have an endurance limit of approximately 0.6 σy whereas porous Ti-6Al-4V alloys have an endurance limit of approximately 0.75 σy. The differences and similarities in the microstructure and their effect on mechanical behavior of the two alloys were also studied by employing scanning electron microscope (SEM).

Fatigue cracking in asphalt mixtures: the effects of ageing and temperature

2017 ◽  
Vol 19 (3) ◽  
pp. 561-570 ◽  
Author(s):  
Fernando Moreno-Navarro ◽  
Miguel Sol-Sánchez ◽  
Gema García-Travé ◽  
Mª Carmen Rubio-Gámez
Keyword(s):  
Fatigue Cracking ◽  
Asphalt Mixtures

Performance of Asphalt Rejuvenators in Hot-Mix Asphalt Containing Recycled Asphalt Shingles

2017 ◽  
Vol 2633 (1) ◽  
pp. 108-116 ◽  
Author(s):  
Max A. Aguirre ◽  
Marwa M. Hassan ◽  
Sharareh Shirzad ◽  
Louay N. Mohammad ◽  
Samuel B. Cooper
Keyword(s):  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Fatigue Cracking ◽  
Strain Energy Release ◽  
Asphalt Mixtures ◽  
Bending Test ◽  
Test Results ◽  
Recycled Asphalt ◽  
Recycled Asphalt Shingles ◽  
Asphalt Shingles

The use of recycled asphalt shingles (RAS) in asphalt paving construction represents a sustainable approach to reduce virgin material consumption and negative environmental effects, as well as the cost of asphalt pavement. However, many challenges are yet to be addressed about the use of RAS in paving applications. This study evaluated the effect of the incorporation of postconsumer waste shingles and rejuvenators on the performance of hot-mix asphalt. Four asphalt rejuvenators—one bio-oil and three synthetic oils—were evaluated. A set of laboratory tests was conducted to characterize the performance of asphalt mixtures against permanent deformation and fatigue cracking. The addition of 5% RAS showed an improvement in permanent deformation when compared with a conventional mixture with no RAS. Yet the addition of asphalt rejuvenator products slightly decreased the performance against permanent deformation. On the basis of Hamburg wheel-tracking device test results, the addition of RAS did not adversely affect moisture resistance. Yet semicircular bending test results showed that the asphalt mixtures that contained asphalt rejuvenators had a lower critical strain energy release rate than the minimum threshold value (0.5 kJ/m2), which indicated a greater susceptibility to intermediate-temperature cracking.

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