One-Dimensional Nonlocal Model for Gyratory Compaction of Hot Asphalt Mixtures

2022 ◽  
Vol 148 (2) ◽  
Author(s):  
Tianhao Yan ◽  
Mihai Marasteanu ◽  
Jia-Liang Le
2019 ◽  
Author(s):  
Teng Man

The compaction of asphalt mixture is crucial to the mechanical properties and the maintenance of the pavement. However, the mix design, which based on the compaction properties, remains largely on empirical data. We found difficulties to relate the aggregate size distribution and the asphalt binder properties to the compaction behavior in both the field and laboratory compaction of asphalt mixtures. In this paper, we would like to propose a simple hybrid model to predict the compaction of asphalt mixtures. In this model, we divided the compaction process into two mechanisms: (i) visco-plastic deformation of an ordered thickly-coated granular assembly, and (ii) the transition from an ordered system to a disordered system due to particle rearrangement. This model could take into account both the viscous properties of the asphalt binder and grain size distributions of the aggregates. Additionally, we suggest to use the discrete element method to understand the particle rearrangement during the compaction process. This model is calibrated based on the SuperPave gyratory compaction tests in the pavement lab. In the end, we compared the model results to experimental data to show that this model prediction had a good agreement with the experiments, thus, had great potentials to be implemented to improve the design of asphalt mixtures.


Author(s):  
H. Barry Takallou ◽  
Hussain U. Bahia ◽  
Dario Perdomo ◽  
Robert Schwartz

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.


2021 ◽  
pp. 91-97
Author(s):  
A. Margaritis* ◽  
T. Tanghe ◽  
J. De Visscher ◽  
S. Vansteenkiste ◽  
A. Vanelstraete

2013 ◽  
Vol 2013 ◽  
pp. 1-10
Author(s):  
Qun Chen ◽  
Yuzhi Li

Compaction characteristic of the surface layer asphalt mixture (13-type gradation mixture) was studied using Superpave gyratory compactor (SGC) simulative compaction tests. Based on analysis of densification curve of gyratory compaction, influence rules of the contents of mineral aggregates of all sizes and asphalt on compaction characteristic of asphalt mixtures were obtained. SGC Tests show that, for the mixture with a bigger content of asphalt, its density increases faster, that there is an optimal amount of fine aggregates for optimal compaction and that an appropriate amount of mineral powder will improve workability of mixtures, but overmuch mineral powder will make mixtures dry and hard. Conclusions based on SGC tests can provide basis for how to adjust material composition for improving compaction performance of asphalt mixtures, and for the designed asphalt mixture, its compaction performance can be predicted through these conclusions, which also contributes to the choice of compaction schemes.


1994 ◽  
Vol 116 (3) ◽  
pp. 256-259 ◽  
Author(s):  
Z. P. Bazˇant ◽  
M. Jira´sek

A micromechanically based enrichment of the nonlocal operator by a term taking into account the directional dependence of crack interactions (Bazˇant, 1992) can be expected to improve the performance of the nonlocal model. The aim of this paper is to examine this new model in the context of a simple localization problem reducible to a one-dimensional description. Strain localization in an infinite layer under plain stress is studied using both the old and the new nonlocal formulations. The importance of renormalization of the averaging function in the proximity of a boundary is demonstrated and the differences between the localization sensitivity of the old and new model are pointed out.


2017 ◽  
Vol 12 (1) ◽  
pp. 30-37 ◽  
Author(s):  
Tran Thanh Nhat ◽  
Osamu Takahashi

Simple indices easily help to evaluate a performance of hot mix asphalt mixtures. This study aimed to develop a simple workability index and rutting resistance index for wearing course mixtures. Seven aggregate gradations were prepared to investigate dense, coarse, and fine-graded hot mix asphalt mixtures. The study used the Marshall compactor to fabricate specimens. The Superpave Gyratory Compaction was employed to measure the workability of the seven blends, namely the workability energy parameter of asphalt mixtures. The study also conducted Wheel Tracking Test to evaluate rutting resistance of those mixtures. The results showed a strong relationship between the workability index and the workability energy of hot mix asphalt mixtures, namely increasing the workability energy of mixtures with increasing the workability index value. The workability energy value of an asphalt mixture may be high when the area of continuous maximum density for a proportion of stone, which illustrates a degree of far away from the Fuller maximum density line, is low. Moreover, the rutting resistance index correlated well with rutting resistance of the hot mix asphalt mixtures.


2010 ◽  
Vol 152-153 ◽  
pp. 1289-1292
Author(s):  
Qun Chen

Through analysis of densification curve characteristic of gyratory compaction, influence rules of the content of mineral aggregates of all sizes and asphalt on compaction characteristic of mixtures were studied. Test studies show that the mixture having more of asphalt has a faster density-increasing speed, that there is an optimal amount of fine aggregates for optimal compaction, and that an appropriate amount of mineral powder will improve workability of mixtures but overmuch mineral powder will make mixtures dry and hard. Conclusions from this research can provide basis for how to adjust material composition for improving compaction performance of mixtures.


2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Bangwei Wu ◽  
Xing Wu ◽  
Liping Liu ◽  
Peng Xiao

Shear strength is one of the important mechanical properties of asphalt mixtures, which is affected by a combination of various parameters such as asphalt property, gradation, and asphalt content, so it often requires a large number of tests to obtain a satisfactory asphalt mix design result. Thus, a shear strength prediction model considering the effects of various factors is proposed to guide the design of asphalt mixes. Firstly, on the foundation of analyzing the factors affecting the shear strength of asphalt mixtures, composed bulk specific gravity of mineral materials, aggregate surface energy, nonrecoverable creep compliance Jnr3.2, gradation index, aggregate specific surface area, asphalt content, and gyratory compaction number were selected as the input parameters for modeling. Secondly, the effects of modeling parameters on shear strength were analyzed, and an appropriate model was established using the software Origin with 101 sets of test results. In the end, the prediction model was verified using extra 18 sets of test data. The result showed that the correlation coefficient between the predicted and measured value reached 0.8 or more, indicating that the model has satisfactory prediction accuracy. This prediction model proposed in this article can be used to reduce the workload for designing asphalt mixtures and promote the establishment of the performance-based design method of asphalt mixtures.


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