scholarly journals Nanoscale Quantification of Moisture Susceptibility of Paving Asphalts

2019 ◽  
Vol 271 ◽  
pp. 03005 ◽  
Author(s):  
Sumon Roy ◽  
Zahid Hossain

Moisture-induced damage due to stripping is one of the major concerns to the highway agencies in recent years. In this study, nanoscopic investigations were carried out to examine the effects of moisture in asphalt binders. An Atomic Force Microscope (AFM) was used to estimate the asphalt binder’s modulus and adhesion values, which were believed to be indicators of binder’s resistance to moisture damage. To this end, two Performance Grade (PG) binders and their modified counterparts using polyphosphoric acid (PPA), styrene-butadiene-styrene (SBS), and SBS plus PPA were tested in this study. Test results show significant reductions of adhesion and modulus values after water immersion of the asphalt binders. AFM data also reveals that SBS-modified binders exhibit better moisture resistance compared to the base binder. Findings of this study are expected to help transportation professionals to achieve a better understanding of moisture damage of asphalt binders at a molecular level and their suitability in pavements.

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Han Wang ◽  
Yinchuan Guo ◽  
Aiqin Shen ◽  
Xiaolong Yang ◽  
Peng Li

Moisture susceptibility plays an important role in the damage of asphalt pavement. Failure occurs when asphalt is removed from the aggregate particles due to the decreased adhesion between the asphalt and aggregate in comparison with that between water and the aggregate. In recent years, efforts utilizing nanomaterials to improve the diverse properties of asphalt have proven to be effective. In this study, three types of nanoclays were used to modify styrene-butadiene-styrene- (SBS-) modified asphalt. The resistances to water damage of the modified binders were evaluated using the surface free energy (SFE) and atomic force microscopy (AFM). The results revealed that the total SFE decreased and the energy ratio (ER) increased when the asphalt binder was modified with the nanoclays, indicating that the addition of nanoclays can improve the moisture resistance of these aggregate-binder systems. After immersion, a decreased amount of bee structures was observed in both the SBS and nanoclay-modified asphalts due to the interactions between water and bitumen. However, the residual amount of bee structures was higher in the nanoclay-modified asphalts than in the SBS-modified asphalt, indicating that the addition of nanoclay makes the surface morphology of asphalt more resistant to water damage. Finally, freeze-thaw splitting tests were used to verify the results obtained through the SFE and AFM tests.


2017 ◽  
Vol 2632 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Evan W. Holcombe ◽  
Munir D. Nazzal ◽  
Walaa Mogawer ◽  
Alexander J. Austerman ◽  
Savas Kaya

This paper summarizes the results of a laboratory testing program conducted to evaluate the microstructure, adhesion, and other mechanical properties of asphalt binders meeting the same performance grade (PG) but produced by using different processes and modifiers. To that end, atomic force microscope (AFM) tapping mode imaging and force spectroscopy experiments were conducted on different straight-run and modified asphalt binders meeting the same PG. In addition, bitumen bond strength and semicircular beam (SCB) tests were conducted on the different binders evaluated and on the mixes prepared by using those binders, respectively, for comparison. The AFM images indicated that the microstructure of the modified binders was different from those of the straight-run binders. The AFM force spectroscopy test results showed that binders with the same PG could have significantly different adhesion properties. The results of the SCB tests indicated that the fatigue performance was affected by the adhesion properties of the binders evaluated. The AFM bonding energy had a very good correlation with the flexibility index parameter obtained from SCB test results. The results of this paper suggest that the adhesion properties of asphalt binders should be included in their evaluation process and specifications.


2019 ◽  
Vol 46 (3) ◽  
pp. 188-194 ◽  
Author(s):  
Éric Lachance-Tremblay ◽  
Michel Vaillancourt ◽  
Daniel Perraton ◽  
Hervé Di Benedetto

In this paper, the moisture susceptibility of different bituminous binders with two substrates (glass and limestone) was investigated. To that end, the tensile strength of different combinations of bituminous binder–substrate bond was measured using a pull-off test. This test was adapted from the pneumatic adhesion tensile testing instrument (PATTI) test to improve repeatability. Samples were tested in dry condition and after a 7-day conditioning in hot water bath (60 °C). An analysis of variance (ANOVA) was performed on the test results. Overall, the results show that in dry condition, the pull-off strength is a function of the bituminous binder type rather than of the substrate type. After water conditioning, an increase in the pull-off strength was observed for the bituminous binder without polymers and coupled with glass substrate. This was associated with an increase in binder stiffness. For the limestone substrate, the effect of water conditioning was significant only for one type of binder.


Author(s):  
Moses Akentuna ◽  
Louay N. Mohammad ◽  
Sanchit Sachdeva ◽  
Samuel B. Cooper ◽  
Samuel B. Cooper

Moisture damage of asphalt mixtures is a major distress affecting the durability of asphalt pavements. The loaded wheel tracking (LWT) test is gaining popularity in determining moisture damage because of its ability to relate laboratory performance to field performance. However, the accuracy of LWT’s “pass/fail” criteria for screening mixtures is limited. The objective of this study was to evaluate the capability of the LWT test to identify moisture susceptibility of asphalt mixtures with different moisture conditioning protocols. Seven 12.5 mm asphalt mixtures with two asphalt binder types (unmodified PG 67-22 and modified PG 70-22), and three aggregate types (limestone, crushed gravel, and a semi-crushed gravel) were utilized. Asphalt binder and mixture samples were subjected to five conditioning levels, namely, a control; single freeze–thaw-; triple freeze–thaw-; MiST 3500 cycles; and MiST 7000 cycles. Frequency sweep at multiple temperatures and frequencies, and multiple stress creep recovery tests were performed to evaluate asphalt binders. LWT test was used to evaluate the asphalt mixture samples. Freeze–thaw and MiST conditioning resulted in an increase in stiffness in the asphalt binders as compared with the control. Further, freeze–thaw and MiST conditioning resulted in an increase in rut depth compared with the control asphalt mixture. The conditioning protocols evaluated were effective in exposing moisture-sensitive mixtures, which initially showed compliance with Louisiana asphalt mixture design specifications.


Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3326
Author(s):  
Amirhossein Ghasemirad ◽  
Nura Bala ◽  
Leila Hashemian

Asphalt binder comprises four main fractions—asphaltenes (A), saturates (S), aromatics (A), and resins (R)—referred to as “SARA”. Asphaltenes plays an important role in determining the linear viscoelastic behavior of asphalt binders. In this research, asphaltenes are added as a distinct modifier to improve the performance properties of asphalt binder. The modified binders are aged using a rolling thin film oven. A dynamic shear rheometer is then used to measure the rheological properties of the binders at high temperatures. Changes in the chemical composition of the modified binders are also studied through the determination of SARA fractions, using precipitation and gravity-driven chromatography methods. The rheological results show that asphaltenes improve the stiffness and elasticity of asphalt binder. It is also shown that the addition of asphaltenes raises the high Performance grade (PG) temperature of the asphalt binder, with every 6% of asphaltenes added resulting in a one-interval increase in high PG temperature grade. SARA analysis shows that the increase in polar fraction content due to the addition of asphaltenes causes the stiffness, elasticity, and viscosity of asphalt binders to increase. The results indicate that asphaltenes are an effective yet inexpensive additive to improve asphalt binder properties at high temperatures.


2019 ◽  
Vol 271 ◽  
pp. 03008
Author(s):  
MM Tariq Morshed ◽  
Mohammad Nazmul Hassan ◽  
Zahid Hossain

For characterizing the polymer modified binders, different state Departments of Transportation (DOTs) use different time consuming and empirical Performance Grade (PG) Plus test methods. Furthermore, the PG Plus tests are silent when asphalt binders are modified with chemicals such as polyphosphoric acid (PPA). But, the effects of the polymer are not accurately identified through these conventional tests such as Elastic Recovery (ER) and tenacity. The main goal of this study is to recommend alternative test method(s), which can possibly be pursued by using, a Dynamic Shear Rheometer (DSR). Thus, Multiple Stress Creep and Recovery (MSCR), ER-DSR, Frequency Sweep, and Binder Yield Energy Test (BYET) are being explored to find their effectiveness. Three PG binders (PG 64-22, PG 70-22 and PG 76-22) have been selected for this investigation. These binders have been prepared with styrene-butadiene-styrene (SBS) polymer, PPA, or a combination of both. Further, chemical tests such as SARA (Saturate, Aromatic, Resin, and Asphaltene) analysis and FTIR (Fourier-transform Infrared spectroscopy) are also being explored to fulfill the objectives. Preliminary findings suggest that the PG Plus tests deem to be obsolete. Also, a single test procedure is not sufficient to identify the presence and effectiveness of modifiers in the PG binders.


2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Yuefeng Zhu ◽  
Yanwei Li ◽  
Chundi Si ◽  
Xiaote Shi ◽  
Yaning Qiao ◽  
...  

In recent years, the significant demand for sustainable paving materials has led to a rapid increase in the utilization of reclaimed asphalt pavement (RAP) materials. When RAP is mixed with virgin asphalt concrete, particularly when its percentage is high, performance of the binder and asphalt concrete can be adversely affected. For this reason, different types of additives need to be identified and evaluated beforehand to mitigate the adverse effects. In this study, different types of fiber materials were identified and selected as binder/mixture additives, including lignin fiber (LF), polyester fiber (PF), and basalt fiber (BF). Various samples of fiber-modified binders and asphalt mixtures with different RAP contents (0%, 20%, and 40%) were prepared and were evaluated using two sets of laboratory testing: (i) dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests were performed to study the rheological properties of fiber-modified binders; (ii) the wheel tracking test, bending creep test, moisture susceptibility test, fatigue test, and self-healing fatigue test were conducted to characterize the laboratory properties of fiber-modified RAP mixtures. Test results for the modified binders show that the BF-modified binder has the greatest positive effect on the high-temperature performance of the asphalt binder, followed by PF- and LF-modified binders. However, the virgin asphalt shows the best low-temperature property than the fiber-modified asphalt binder. Test results for the whole RAP mixtures show that all fibers have a significant effect on the properties (including high- and low-temperature stability, moisture susceptibility, fatigue, and self-healing ability) of RAP mixtures. Among them, adding BF shows the greatest improvement in high-temperature stability, fatigue resistance, and self-healing ability of RAP mixtures. LF is found to significantly enhance low-temperature properties, and PF can greatly improve the resistance to moisture damage of RAP mixtures. For high percentage of RAP using on sites, adding multiple additives may further enhance its durability.


Author(s):  
Gholam Hossein Hamedi ◽  
Ali Reza Azarhoosh ◽  
Mojtaba Khodadadi

In this study, the effect of using Polypropylene (PP) as an antistripping additive of asphalt mixtures is investigated. Here, the moisture susceptibility of asphalt mixtures is evaluated by determining the micro-mechanisms using the surface free energy (SFE) concept. The adhesion bond between the aggregate and asphalt binder and the cohesion strength of the asphalt binder are considered as the main factors that affect moisture damage of asphalt mixtures. Test results indicate that the use of PP improves the resistance of asphalt mixtures in both wet and dry conditions. Also, the results of the SFE tests showed that the modifying asphalt binder with PP increases free energy of adhesion that will improve adhesion resistance between asphalt binder-aggregates. The amount of debonding energy in the samples which are modified with PP is lower than the control samples. This shows that by modifying asphalt binders, the tendency of asphalt binder-aggregate stripping can be reduced. The results show the total SFE of the asphalt binders of the modified samples have more free energy rather than the control samples. This phenomenon shows that failure in the asphalt binder film and cohesion failure will be happened more rarely.


2017 ◽  
Vol 50 (3) ◽  
pp. 256-275 ◽  
Author(s):  
Mahdi Delaviz Bayekolaei ◽  
Koorosh Naderi ◽  
Fereidoon Moghadas Nejad

In recent years, the use of nano materials for improving various mechanical and performance-related properties of polymer-modified asphalt binders has been growing rapidly. However, few researches investigated the effects of base binder and styrene–butadiene–styrene (SBS) structure on rutting resistance of polymer-nanocomposite-modified asphalt mixtures. This study investigated the effect of polymer–nanocomposite modification, using two different penetration grade asphalt binders and two types of SBS, on rutting properties of asphalt mixtures. Rheological properties of modified binders, Marshall stability, resilient modulus, and rut depth in wheel-tracking tests were used to evaluate the rutting performance of the modified binders and mixtures. The results indicated that both base binder type and SBS structure had significant effect on rutting resistance of polymer-nanocomposite-modified asphalt mixtures.


2012 ◽  
Vol 509 ◽  
pp. 136-141
Author(s):  
Zhi Fei Liu ◽  
Jia Ping Liu ◽  
Jin Xiang Hong ◽  
Chong Huang

Research in the laboratory was carried out to determine if addition of warm mix asphalt additive (Sasobit) has potential to reduce the temperature comparison with control mix. To fulfill this purpose five types of asphalt binders have been produced with a Sasobit additive in concentration range from 0 to 10% by weight of the asphalt. Viscosity test and dynamic shear rheometer test are conducted for the investigation of effects of Sasobit on rheological properties characteristics of binders. Viscosity tests on binders indicated that the Sasobit binders had significantly lower viscosities compared to control binders at the temperature above 100°C, indicating that Sasobit can reduce the mixing and compaction temperatures above the melting point of Sasobit. Sasobit modified binders are more sensitive cracking and had more excellent rutting resistance properties at service temperatures compared with original bitumen. Based on the test results, the suggest content of Sasobit addition is 3% by weight.


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