AYMA: Mechanistic Probabilistic System To Evaluate Flexible Pavement Performance

1998 ◽  
Vol 1629 (1) ◽  
pp. 137-148 ◽  
Author(s):  
Manuel Ayres ◽  
Matthew W. Witczak

A new rational mechanistic model for analysis and design of flexible pavement systems has been developed. Furthermore, a fundamental probabilistic approach was incorporated into this system to account for the uncertainty of material and environmental conditions. The system was integrated in a user-friendly Windows program with a variety of user-selected options that include widely used models and those recently developed in the Strategic Highway Research Program project. Three basic types of distress can be investigated separately or all together, including fatigue cracking, permanent deformation, and low-temperature cracking. The mechanistic approach makes use of the JULEA layered elastic analysis program to obtain pavement response. The system provides optional deterministic and probabilistic solutions, accounts for aging and temperature effects over the asphalt materials, variable interface friction, multiple wheel loads, and user-selected locations for analysis. Tabular and graphical results provide expected distress values for each month as well as their variability, probability of failure, and assessment of the overall reliability of the pavement relative to each type of distress for a user-selected failure criterion. Only the load-associated module of AYMA is presented; a separate work describes the low-temperature cracking analysis.

2021 ◽  
pp. 009524432110386
Author(s):  
Aboelkasim Diab ◽  
Jorge Pais ◽  
Siyu Chen ◽  
Ankit Gupta ◽  
Xuelian Li ◽  
...  

This paper is oriented to appraise high, intermediate, and low temperature related performance of elastomeric and plastomeric binders and mixtures in order to evaluate their characteristics at various levels of environmental and loading conditions. Artificial oxidative hardening of asphalt binders and mixes was performed in the laboratory using short- and long-term aging protocols.At the binder level, the elastomers (styrene-butadiene-styrene (SBS) and rubber) and plastomer (ethylene-vinyl acetate (EVA)) materials improved high and intermediate temperature performance indices (G*/sin(δ) and G*.sin(δ), respectively). Interestingly, the aged SBS/bitumen blend had improved low-temperature cracking resistance compared to unaged counterpart. With the progress of oxidative hardening, the plastomer based binder did not show obvious change in the low-temperature cracking susceptibility compared to elastomer-modified binder. Seemingly, in the case of plastomer/bitumen blend, the propensity to low-temperature cracking is to a great extent controlled by the corresponding base bitumen. The plastomer based mixture had improved permanent deformation performance, whereas the elastomers afforded a tangible amelioration for the vulnerability to load and non-load associated cracking. The SBS based mixture showed highest low-temperature fracture energy compared to the EVA based mixture. Despite the determinantal effect of age-hardening to low and intermediate temperature-related cracking of mixes, the results confirmed that the elastomeric materials can retard the impact of aging level on the low temperature and fatigue cracking. Comparision of results was justified by the statistical analysis in order to determine the significance of bituminous material parameters on the measured properties.


Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5277
Author(s):  
Shiqi Wang ◽  
Huanyun Zhou ◽  
Xianhua Chen ◽  
Minghui Gong ◽  
Jinxiang Hong ◽  
...  

Semi-flexible pavement (SFP) is widely used in recent years because of its good rutting resistance, but it is easy to crack under traffic loads. A large number of studies are aimed at improving its crack resistance. However, the understanding of its fatigue resistance and fatigue-cracking mechanism is limited. Therefore, the semi-circular bending (SCB) fatigue test is used to evaluate the fatigue resistance of the SFP mixture. SCB fatigue tests under different temperature values and stress ratio were used to characterize the fatigue life of the SFP mixture, and its laboratory fatigue prediction model was established. The distribution of various phases of the SFP mixture in the fracture surface was analyzed by digital image processing technology, and its fatigue cracking mechanism was analyzed. The results show that the SFP mixture has better fatigue resistance under low temperature and low stress ratio, while its fatigue resistance under other environmental and load conditions is worse than that of asphalt mixture. The main reason for the poor fatigue resistance of the SFP mixture is the poor deformation capacity and low strength of grouting materials. Furthermore, the performance difference between grouting material and the asphalt binder is large, which leads to the difference of fatigue cracking mechanism of the SFP mixture under different conditions. Under the fatigue load, the weak position of the SFP mixture at a low temperature is asphalt binder and its interface with other materials, while at medium and high temperatures, the weak position of the SFP mixture is inside the grouting material. The research provides a basis for the calculation of the service life of the SFP structure, provides a reference for the improvement direction of the SFP mixture composition and internal structure.


2010 ◽  
Vol 168-170 ◽  
pp. 1145-1148 ◽  
Author(s):  
Xin Qiu ◽  
Lan Yun Chen ◽  
Liang Xue

The paper investigates the effects of different concentrations of crumb rubber (CR) on the pavement performance of the conventional penetration-grade 80/100 bitumen and the dense-graded wearing course asphalt mixture (AC16). A wet process and 0.6mm size CR were used and the control variables included three types of CR of concentrations 5%,10% and 15% by total weight of binder. The evaluations were twofold. Firstly, a comparison of the basic and rheological properties of those modified and unmodified binders was conducted. Secondly, a comparison of the resistance to moisture damage, low temperature cracking and permanent deformation of the AC16 and CR modified AC16 was performed. The results show that all the CR modified binders and mixtures are found to have improved performance as evaluated by a series of laboratory tests. In addition, among three CR concentrations, AC16 modified with 10%CR by total weight of binder exhibits the most satisfactory performance properties with respect to the resistance to moisture damage, permanent deformation and low temperature cracking.


2021 ◽  
Vol 902 ◽  
pp. 135-143
Author(s):  
Mohammad Ali Khasawneh ◽  
Khalid Ghuzlan ◽  
Nada Bani Melhem

Rutting, fatigue cracking and low temperature cracking are the most important distresses in asphalt pavements as a result of changes in rheological properties of asphalt binder. Many types of modifiers were used to enhance asphalt behavior at both low and high temperatures. In this study, carbon nanotubes (CNT) were used as one of many nanomaterials that take a large attention in the latest research related to asphalt modification against different types of distresses. Effect of CNT on rheological properties of asphalt binder was investigated by testing unmodified and CNT modified asphalt binders using two of Superpave devices: Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR). Penetration, softening point, flash point and rotational viscosity (RV) tests were carried out as well. CNT was added in 0.1%, 0.5% and 1% by weight of asphalt binder. It was found that adding CNT in 0.5% and 1% increase stiffness of asphalt and consequently asphalt pavement rutting resistance. On the other hand, this increase in stiffness affected pavement behavior adversely which is not desirable for fatigue and low temperature cracking. However, Superpave specifications were still satisfied and asphalt binder’s relaxation properties were improved upon CNT modification. It was eventually found that 0.5% of CNT is the optimum percentage for the best performance.


1997 ◽  
Vol 1590 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Peter E. Sebaaly ◽  
Dan Ridolfi ◽  
Raja S. Gangavaram ◽  
Jon A. Epps

Aggregate properties and gradations have been shown to have a significant impact on the strength and performance of HMA mixtures. Strength properties, such as the resilient modulus and tensile strength, and performance properties, such as moisture sensitivity, permanent deformation, and low-temperature cracking, play a major role in the field performance of HMA mixtures. However, it is believed that by changing the aggregate gradation and the asphalt binder, a desirable hot-mix asphalt mixture can be achieved for any source of aggregate. The data and analysis of a laboratory research study that evaluated four gradations and four asphalt binders in conjunction with five sources of Nevada aggregates are summarized. The measured material properties include the Superpave binder and aggregate properties, the strength properties, and the permanent deformation and low-temperature cracking of the mixtures. The data analysis indicated that the resilient modulus and tensile strength tests can be used in lieu of the more complicated triaxial repeated-load test to ensure against rutting and that the binder property can be used to ensure against low-temperature cracking.


2021 ◽  
Vol 6 (4) ◽  
pp. 58
Author(s):  
Ana Dias ◽  
Hugo Silva ◽  
Carlos Palha ◽  
Joel Oliveira

When temperatures drop to significantly low levels, road pavements are subjected to thermally-induced stresses, resulting in the appearance of thermal cracking, among other distresses. In these situations, polymers can be used as asphalt binder modifiers to improve certain asphalt binder properties, such as elastic recovery, cohesion, and ductility. Polymers also minimize some of the problems of asphalt mixtures, such as thermal and fatigue cracking and permanent deformation. This work’s objective was to study the behavior of asphalt mixtures at low temperatures, mainly when using modified binders. Thus, three binders were selected and tested: a standard 50/70 penetration grade bitumen and two polymer-modified binders (PMB), obtained by adding, respectively, 2.5% and 5.0% of styrene–butadiene–styrene (SBS) in the 50/70 pen grade bitumen. Then, the PMBs were incorporated into stone mastic asphalt mixtures (namely SMA 11), which were subjected to low-temperature mechanical tests based on the most recent European Standards. The asphalt binders and mixtures evaluated in this work were tested for thermal cracking resistance, creep, elastic recovery, cohesive strength, and ductility strength. Overall, it is concluded that the studied asphalt mixtures with PMB, with just 2.5% SBS, performed adequately at low temperatures down to −20 °C.


2021 ◽  
Vol 13 (7) ◽  
pp. 4039
Author(s):  
Sara A. Alattieh ◽  
Ghazi G. Al-Khateeb ◽  
Waleed Zeiada

Fatigue cracking and low-temperature cracking are two major distresses that occur in asphalt pavements. Fatigue cracking is a load-associated distress caused by the tensile stresses at the bottom/top of the asphalt concrete (AC) layer due to repeated traffic loading. On the other hand, low-temperature cracking occurs when tensile stresses built up with in the AC layer at low temperatures exceed the tensile strength of that layer. In this study, the performance of date seeds oil bio-modified asphalt binders (DSO-BMB) is evaluated against fatigue and low-temperature cracking. The DSO-BMBs are prepared using volume ratios of 1.5, 2.5, 3.5, 4.5, and 5.5% date seeds oil-to-asphalt binder. The base asphalt binder used in the study is a 60/70-penetration grade with a Superpave performance grade (PG) of PG 64–16. The dynamic shear rheometer (DSR) standard test was used to assess the fatigue performance of the bio-modified binders (BMBs), while the bending beam rheometer (BBR) test was used to test the BMBs for low-temperature performance. In addition, the DSR linear amplitude sweep (LAS) test was used to evaluate the fatigue tolerance behavior of the DSO-BMBs. The analysis and results of the study showed that the bio-oil enhanced the low-temperature performance. The low PG grade improved from −16 °C for the control asphalt binder to −28 °C for the BMB. Additionally, the fatigue resistance of the BMBs was improved as illustrated by the damage–characteristic curves of the modified asphalt binders from the visco-elastic continuum damage (VECD) analysis and the increase in the number of cycles to fatigue failure (Nf).


2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Chunli Wu ◽  
Liding Li ◽  
Yongchun Cheng ◽  
Zhengwei Gu ◽  
Zehua Lv ◽  
...  

As an eco-friendly pavement material, waste tires rubber-modified asphalt mixtures (WRMs) have been applied in pavement engineering widely. To further improve the performance and adaptability of WRM, diatomite and basalt fibers are, respectively, added to WRM. Subsequently, the Marshall tests, the rutting tests, the low-temperature splitting tests, the freeze-thaw splitting tests, and the vibration attenuation tests are conducted to study the effect of diatomite and basalt fibers on pavement properties of WRM. Furthermore, the correlation degree between the content of diatomite, basalt fibers, asphalt, and the pavement properties of WRM is analysed by the grey correlation grade analysis (GCGA). The results show that the addition of diatomite and basalt fibers can significantly improve the pavement and vibration attenuation properties of WRM. The improvement of high-temperature permanent deformation resistance, low-temperature cracking resistance, and water damage resistance of WRM is mainly attributed to diatomite, basalt fibers, and asphalt-aggregate ratio, respectively. The improvement of the vibration attenuation of WRM by diatomite and basalt fibers is mainly attributed to the increase of waste tires rubber-modified asphalt (WRA) content caused by adding diatomite and basalt fibers.


Author(s):  
Ali Arabzadeh ◽  
Joseph H. Podolsky ◽  
Maxwell D. Staver ◽  
R. Christopher Williams ◽  
Austin D. Hohmann ◽  
...  

In this study, asphalt mixtures were engineered with bio-renewable soybean oil-derived modifiers, and then used for pavement demonstration projects in the U.S. states of Iowa and Minnesota in the summer of 2019. The performance grade, elastic recovery (R), and non-recoverable creep compliance (Jnr) of the binders were evaluated. The modification of asphalt binder for the Iowa project almost maintained the high and low temperature grades, and the presence of modifier in the mixture of Minnesota project resulted in a slight decrease in the low temperature grade while maintaining the high temperature grade. The Jnr and R values proved the increase of elasticity and relaxation of the asphalt binder modified for the Iowa project. The Jnr calculated for the Minnesota project revealed a considerable increase in the relaxation of the asphalt binder. Disc-shaped compact tension, Hamburg wheel tracking, and push-pull were the mechanical performance tests performed on the mixtures. Based on the results obtained from these tests, the Iowa mixture, produced with modified asphalt binder, showed a significant improvement in resistance to low-temperature cracking, rutting, moisture damage, and fatigue cracking. The Minnesota mixture, modified in the plant, showed a significant improvement in the fatigue performance and a slight improvement in low-temperature cracking resistance.


2014 ◽  
Vol 599 ◽  
pp. 361-367 ◽  
Author(s):  
Chong Huang ◽  
Jin Xiang Hong ◽  
Jun Tao Lin ◽  
Cheng Deng ◽  
Lin Li

The central concept of semi-flexible pavement (SFP) is to combine the best qualities of concrete and asphalt pavement by means of filling the voids of the large gap asphalt mixture (LGAM) with good fluidity grout. The major purpose of this study is to determine the feasibility of utilizing waste rubber powder in the grout so as to reduce the stiffness of the semi-flexible pavement. In this paper, seven kinds of grout were prepared by adding different volume dosage of the waste rubber powder and seven kinds of SFP were also prepared. By means of rutting, dynamic elastic modulus and low-temperature cracking performance tests, the performances of SFP were compared. The experimental results illustrated that the waste rubber powder was suitable to the semi-flexible pavement material. With the dosage of rubber powder increased, the anti-rutting, dynamic modulus of SFP decreased, but the low-temperature cracking of SFP was improved. Preferably, the volume dosage of the waste rubber powder should be not more than 20%.


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