Evaluation of Viscoelastic and Fracture Properties of Asphalt Mixtures with Long-Term Laboratory Conditioning

Author(s):  
Reyhaneh Rahbar-Rastegar ◽  
Jo Sias Daniel ◽  
Eshan V. Dave

Aging affects the properties of asphalt mixtures in different ways; increase of stiffness, decrease of relaxation capability, and the increase of brittleness, resulting in changes in cracking behavior of asphalt mixtures. In this study, ten plant-produced, lab-compacted mixtures with various compositions (recycled materials, binder grades, binder source, and nominal maximum aggregate size) are evaluated at different long-term aging levels (24 hours at 135°C, 5 days at 95°C, and 12 days at 95°C on loose mix and 5 days at 85°C on compacted specimens). The asphalt mixture linear viscoelastic properties (|E*| and δ) and master curve shape parameters measured from complex modulus testing and fracture properties (measured from disc-shaped compact tension and semi-circular bending fracture testing) are compared at different levels of aging. The results indicate that the mixture exposure time to aging is proportional to the dynamic modulus and phase angle changes. Generally, the fracture parameters of mixtures become worse when aging level changes from 5 to 12 days aging. In spite of the similar viscoelastic properties, the mixtures with 24 hours at 135°C and 12 days at 95°C aging do not show similar fracture parameters.

Author(s):  
Runhua Zhang ◽  
Jo E. Sias ◽  
Eshan V. Dave ◽  
Reyhaneh Rahbar-Rastegar

Aging can significantly affect the viscoelastic properties and cracking behavior of asphalt mixtures, causing increase in stiffness, reduction in relaxation capability, and increase in brittleness. Eleven mixtures are evaluated using different laboratory conditioning protocols to evaluate how the properties of asphalt mixtures, including viscoelastic properties, fatigue, and fracture behavior will change over time. Comparisons between different aging levels and mixtures are conducted by using complex modulus (E*) (field cores are included), simplified viscoelastic continuum damage (S-VECD) approach, semi-circular bending (SCB), and disk shaped compact tension (DCT) fracture tests. The climatic aging index developed by the NCHRP 09-54 project is utilized in this study to calculate the appropriate field aging duration corresponding to the different laboratory aging protocols. Pavement evaluation tools FlexPAVETM and IlliTC are also used to predict and compare the fatigue and thermal cracking performance of these mixtures. The results of E* and S-VECD tests indicate that the mixtures are more prone to fatigue cracking with aging, and the two long-term conditioning protocols induce statistically similar changes in linear viscoelastic and fatigue properties. However, prediction of fatigue performance from FlexPAVE TM does not show a consistent trend once pavement structure and traffic are considered. Fracture tests and IlliTC predictions show the virgin mixtures and those with soft base binders will have better capability to resist cracking after long-term aging. In this study, the two mixtures with the largest difference between high and low temperature performance grade (PG) show the largest change in fracture and fatigue properties with aging.


2015 ◽  
Vol 77 (23) ◽  
Author(s):  
Mohd Khairul Idham ◽  
Mohd Rosli Hainin ◽  
M. Naqiuddin M. Warid ◽  
Noor Azah Abdul Raman ◽  
Rosmawati Mamat

Hot mix asphalt (HMA) pavement encounter short and long term aging throughout the service life. Laboratory aging is the method used to simulate field aging process of HMA pavement. This study was undertaken to determine the long term effect of different binder and mixture laboratory aging methods on HMA (binder aging and mixture aging). Three types of HMA mixtures were prepared for this study namely Asphaltic Concrete with 10 mm nominal maximum aggregate size (AC 10), Asphaltic Concrete 14 mm (AC 14) and Asphaltic Concrete 28 mm (AC 28). These specimens were conditioned with nine different methods and durations.  Resilient modulus test was carried out at 40˚C as an initial indicator of the specimen performance. Permanent deformation of the same specimens was then evaluated by dynamic creep test. Generally, the aged asphalt binder specimens have higher resilient and stiffness modulus compared to aged asphalt mixture specimens. In addition, aged binder specimens have a lower permanent strain which indicates higher resistance to permanent deformation. This study also found that high resilient and stiffness modulus of specimens is attributed by different in heating frequency, temperature, air exposure and binder content of the mixtures.


2021 ◽  
Vol 11 (5) ◽  
pp. 2289
Author(s):  
Keke Lou ◽  
Xing Wu ◽  
Peng Xiao ◽  
Aihong Kang ◽  
Zhengguang Wu ◽  
...  

There are many parameters that could affect the properties of asphalt mixtures, such as the fiber additive, gradation type, nominal maximum aggregate size (NMAS), and asphalt. To evaluate the influence of these factors on the crack resistance of asphalt mixture, 10 different types of asphalt mixtures were prepared. The indirect tensile asphalt cracking test (IDEAL-CT) and semi-circle bending test (SCB) were adopted to test the anti-cracking ability of the test samples. The parameters of these two test results were also used to conduct the correlation analysis to find the correlation between different parameters, and scanning electron microscope (SEM) test was also used to analyze the micro cracks of asphalt mixture. The results showed that basalt fiber could further enhance the anti-cracking ability of asphalt mixture. Stone matrix asphalt (SMA) showed better anti-cracking performance than Superpave (SUP) asphalt mixtures. The increase in the nominal maximum aggregate size could decrease the anti-cracking ability of asphalt mixtures. Styrene-Butadiene-Styrene (SBS) modified asphalt could better reinforce the anti-cracking ability than pure asphalt. The CTindex of IDEAL-CT test and Flexibility index (FI) value of SCB test results showed better correlation. This paper has certain significance in guiding the design of asphalt mixtures having good crack resistance.


Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 811
Author(s):  
Pavla Vacková ◽  
Jan Valentin ◽  
Majda Belhaj

The paper presents the influence of laboratory aging simulation on fracture properties determined on 150 variants of asphalt mixtures. The fracture properties were determined by two different test approaches—semi-circular bending test (SCB test) and three-point bending test on beam specimens (3-PB test). The aging was simulated according to one of the methods defined in EN 12697-52 (storage of test specimens in chamber at temperature of 85 °C for 5 days). The evaluated group of variants covered asphalt mixtures for all road layers. The group was further divided according to used bituminous binder (unmodified vs. modified) and reclaimed asphalt content. The results showed that strength parameters (flexural strength and fracture toughness) increase with aging. It further shows that fracture work provides more complex information about the cracking behavior. For the aging indexes, it was found that for mixtures with modified binders and mixtures which did not contain reclaimed asphalt (RA), the values were higher. The aging indexes for fracture work showed different results for both performed tests.


2015 ◽  
Vol 77 (32) ◽  
Author(s):  
Mohd Khairul Idham ◽  
Mohd Rosli Hainin

In pavement industries, incorporating appropriate amount of reclaimed asphalt pavement (RAP) in the fresh mixtures is one of the approaches to attain sustainable principle in construction. Usage RAP materials have been practiced since 1970s, however, pavements made with RAP will reach the end of service life and need to be recycled again. Only a few studies done on the second recycle of RAP (R2AP). Therefore, this paper aimed to investigate the effect of incorporating RAP and R2AP in the asphalt mixture. RAP was collected from in-service road which was exposed to the environment and traffic for seven years. While, the second cycle of RAP (R2AP) was obtained through the laboratory aging process.  20, 40, and 60 % of RAP and R2AP were mixed with fresh dense graded aggregates to form Asphaltic Concrete with 14 mm nominal maximum aggregate size (AC 14). Resilient modulus test was performed to evaluate the performance on rutting resistance. Tensile strength was also evaluated at 25 °C as an indicator for fatigue resistance. 60 % of RAP and 40 % of R2AP are observed to the best optimum amount to be added in the fresh mixture in order to improve both fatigue and rutting resistance.


2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Biao Ding ◽  
Xiaolong Zou ◽  
Zixin Peng ◽  
Xiang Liu

To determine and compare the fracture properties of different asphalt mixtures, single-edge notched beam (SENB) tests using three types of asphalt mixtures were applied in this study under the conditions of different notched depths and different temperatures. The effects of notched depths and temperatures on the fracture toughness and fracture energy were analyzed. The results indicate that the notch depth has no significant effects on the fracture toughness and the fracture energy, but the gradation has relatively obvious effects on the fracture energy, which the larger contents of course aggregate leads to increase the discreteness of the fracture energy of the specimen. The temperature has significant effects on the ultimate loads, fracture energy, and fracture toughness. The ultimate loads of the SENBs reach the peak value at 0°C, which could be resulted in that viscoelastic properties of asphalt mixture depend with temperatures. The fracture toughness at −20°C of continuously graded asphalt mixtures are higher than those of gap-graded asphalt mixtures. On the contrary, the fracture toughness of gap-graded asphalt mixtures is higher at temperatures from −10°C to 20°C. The fracture energy increases with temperatures, and the fracture energy of SMA-13 is significantly larger than those of AC-13 and AC-16.


2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Seong-Hyeok Lee ◽  
Dae-Wook Park ◽  
Hai Viet Vo ◽  
Samer Dessouky

The research has been initiated to develop the asphalt mixtures which are suitable for the surface of asphalt concrete directly fastened track (ADFT) system and evaluate the performance of the asphalt mixture. Three aggregate gradations which are upper (finer), medium, and below (coarser). The nominal maximum aggregate size of asphalt mixture was 10 mm. Asphalt mixture design was conducted at 3 percent air voids using Marshall mix design method. To make impermeable asphalt mixture surface, the laboratory permeability test was conducted for asphalt mixtures of three different aggregate gradations using asphalt mixture permeability tester. Moisture susceptibility test was conducted based on AASHTO T 283. The stripping percentage of asphalt mixtures was measured using a digital camera and analyzed based on image analysis techniques. Based on the limited research results, the finer aggregate gradation is the most suitable for asphalt mixture for ADFT system with the high TSR value and the low stripping percentage and permeable coefficient. Flow number and beam fatigue tests for finer aggregate asphalt mixture were conducted to characterize the performance of asphalt mixtures containing two modified asphalt binders: STE-10 which is styrene-butadiene-styrene (SBS) polymer and ARMA which is Crum rubber modified asphalt. The performance tests indicate that the STE-10 shows the higher rutting life and fatigue life.


2021 ◽  
Vol 8 ◽  
Author(s):  
Hasanain Radhi Radeef ◽  
Norhidayah Abdul Hassan ◽  
Ahmad Razin Zainal Abidin ◽  
Mohd Zul Hanif Mahmud ◽  
Nur Izzi Md. Yusoffa ◽  
...  

In recent years, the proliferation of plastic waste has become a global problem. A potential solution to this problem is the dry process, which incorporates plastic waste into asphalt mixtures. However, the dry process often has inconsistent performance due to poor interaction with binder and improper distribution of plastic waste particles in the mixture skeleton. This inconsistency may be caused by inaccurate mixing method, shredding size, mixing temperature and ingredient priorities. Thus, this study aims to improve the consistency of the dry process by comparing the control asphalt mixture and two plastic waste-modified asphalt mixtures prepared using the dry process. This study used crushed granite aggregate with the nominal maximum aggregate size of 14 mm whereas the shredded plastic bag is in the range of 5–10 mm. Quantitative sieving analysis and performance tests were carried out to examine the effects of plastic waste added into the asphalt mixture. The volumetric and performance properties combined with image analysis of the modified mixtures were obtained and compared with the control mixture. In addition, the moisture damage, resilient modulus, creep deformation and rutting were evaluated. This study also highlighted in detail the distribution of plastic particles in the final skeleton of the asphalt mixture. Based on the analysis, an enhanced dry process of mixing procedure was proposed and evaluated. Results showed that the addition of plastic particles using the conventional dry process leads to the deviation in the aggregate structure as high plastic content is added. Furthermore, the enhanced dry process developed in this study presents substantial enhancement in the asphalt performance, particularly with plastic waste that accounts for 20% of the weight of the asphalt binder.


Author(s):  
Samuel B. Cooper ◽  
Louay N. Mohammad ◽  
Mostafa A. Elseifi ◽  
Amar Raghavendra

Mix properties that deviate appreciably from the design properties during the production and construction of asphalt mixtures can lead to premature pavement distress or even failure. The objective of this study was to quantify the differences in the dynamic modulus of specimens prepared during design, production, and construction of dense-graded asphalt pavements and their effects on pavement performance prediction. For the achievement of this objective, Superpave® mixtures were collected from Iowa, Florida, Virginia, Michigan, South Dakota, Louisiana, Minnesota, and Wisconsin during design [laboratory-mixed and laboratory-compacted (LL)], production [plant-produced and laboratory-compacted (PL)], and construction [plant-produced and field-compacted (PF) specimens]. The nominal maximum aggregate size was kept constant at 12.5 mm. An indirect tension dynamic complex modulus (IDT | E*|) was measured for the three specimen types (i.e., LL, PL, and PF). Results showed that laboratory-compacted and field-compacted specimens exhibited large and significant differences. This finding was attributed to differences in the compaction effort and procedure between the field and the laboratory. Results of the AASHTOWare Pavement ME Design showed that the use of dynamic moduli obtained from different specimen types would result in significant differences in pavement performance prediction. This research was part of NCHRP Project 9-48, Field Versus Laboratory Volumetrics and Mechanical Properties.


2020 ◽  
Vol 13 (6) ◽  
pp. 637-644
Author(s):  
Saman Salari ◽  
Samuel Cooper ◽  
Louay N. Mohammad ◽  
Peyman Barghabany

AbstractThe Louisiana Department of Transportation and Development (DOTD) and other state agencies are continuously looking for techniques to reduce roadway maintenance and construction costs. A common consideration is to introduce asphalt mixtures with a smaller nominal maximum aggregate size (NMAS) for utilization in roadways. In a previous study, DOTD concluded that mixtures with a 4.75 mm NMAS provided acceptable performance as a surface layer. Excessive stockpiles of unused smaller aggregates can result in an economically competitive source to be consi dered for asphalt mixtures. The DOTD developed mixtures with four aggregate types and two binder types. A comprehensive evaluation of performance was conducted through volumetric and mechanistic testing. Performance testing consisted of the Loaded Wheel Tracking (LWT) test to determine rutting resistance, Semi-Circular Bend (SCB) test to evaluate intermediate temperature cracking resistance, and dynamic modulus (E*) to ascertain the stiffness at intermediate temperatures. As expected, asphalt binder grade, aggregate type and mixture composition affected the performance of mixtures evaluated. Gravel mixtures were susceptible to cracking, while limestone mixtures were susceptible to rutting. An economic analysis was conducted to determine the viability of 4.75 mm mixtures. The cost per ton of 4.75 mm mixtures in Louisiana was higher than conventional 12.5 mm mixtures. However, when considering the lift thickness of potential overlays, the 4.75 mm aggregate mixtures became more viable. Further, a life-cycle analysis of a designed pavement using AASHTO Pavement-ME was performed to compare the lifetime durability of the 4.75 mm NMAS mixtures to a conventional 12.5 mm mixture.


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