Generalized Methodology to Develop Mechanistically Informed Asphalt Mixture Layer Coefficients for AASHTO 1993 Pavement Design Approach

2021 ◽  
pp. 036119812110415
Author(s):  
Rasool Nemati ◽  
Eshan V. Dave ◽  
Jo E. Sias
Keyword(s):  
New Hampshire ◽  
Fatigue Testing ◽  
Complex Modulus ◽  
Performance Testing ◽  
Asphalt Mixtures ◽  
Pavement Design ◽  
Design Approach ◽  
Normal Distribution Function ◽  
Central Plant ◽  
Base Course

This paper presents a generalized framework for determining mechanistically informed layer coefficients (a-values) for asphalt mixtures in the AASHTO empirical pavement design approach. The layer coefficients influence the layer thicknesses and consequently the structural capacity of pavements. Therefore, it is critical to determine reliable mechanistically informed a-values. A set of 18 commonly used asphalt mixtures in New Hampshire was selected for investigation including different types of hot mix and cold central plant recycled mixtures that are used as wearing, binder, and base course layers. Laboratory characterization was conducted using the complex modulus, semi-circular bend, and direct tension cyclic fatigue testing methods. The mixtures were evaluated using three performance index parameters: complex modulus rutting index parameter, rate-dependent cracking index parameter, and a new continuum damage parameter ([Formula: see text]). The measured field performance of wearing course mixtures in terms of International Roughness Index was used to back-calculate the in situ performance-based layer coefficients (aIRI-values). Using a normal distribution function, the results from performance testing were incorporated with the aIRI-values to develop mechanistically informed mix-specific layer coefficients. In addition, a typical layer coefficient at specific reliability levels for each mix category including hot mix wearing course, hot mix binder and base course as well as cold central plant recycled mix course are proposed for New Hampshire. The recommended a-values are 0.48 for hot mix wearing, 0.41 for hot mixed binder and base, and 0.28 for cold recycled base mixtures; these are approximately 25% higher than the currently used a-values in New Hampshire.

Evaluation of Laboratory Performance and Structural Contribution of Cold Recycled Versus Hot Mixed Intermediate and Base Course Asphalt Layers in New Hampshire

2019 ◽  
Vol 2673 (6) ◽  
pp. 467-476 ◽  
Author(s):  
Rasool Nemati ◽  
Eshan V. Dave ◽  
Jo E. Sias ◽  
Eric S. Thibodeau ◽  
Ryan K. Worsman
Keyword(s):  
New Hampshire ◽  
Complex Modulus ◽  
Resilient Modulus ◽  
Asphalt Binder ◽  
Asphalt Mixtures ◽  
Direct Tension ◽  
Local Conditions ◽  
Laboratory Performance ◽  
Structural Contribution ◽  
Base Course

Depending on the local conditions and structural design of the pavement, multiple asphalt concrete layers including base, intermediate, and wearing courses are used. Typically, the base and intermediate layers have larger aggregate sizes and lower total asphalt binder contents as compared with the wearing course. Recently, cold recycled (CR) asphalt mixtures have gained attention as an alternative to the typical base, and to some extent intermediate courses, because of economic and environmental advantages. Challenges with CR include the potential high variability of recycled asphalt pavement (RAP) and lack of knowledge in relation to structural contribution and long-term performance of such layers. This study investigates four different types of CR and four hot mixed plant-produced asphalt mixtures (three intermediate courses and one base course) that are typical mixtures used in New Hampshire. The laboratory performance evaluation is conducted through the resilient modulus (Mr), complex modulus (E*), semi-circular bend and direct tension cyclic fatigue (S-VECD) tests. Pavement performance prediction is carried out using the results from S-VECD approach in the FlexPAVETM software. The test results indicate that the performance of CR is highly affected by the amount of oil distillate percentage in the emulsion as well as the amount of recovered binder in the RAP. While having a relatively lower rutting resistance capability, the CR mixtures maintained an acceptable fatigue performance. As compared with CR mixtures, hot mixed intermediate and base course mixtures indicated better rutting performance while having lower resistance to cracking.

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).

Flexural Resistance Analysis on Hot Asphalt Mixtures with Wire Mesh Placement Modeling as Reinforcement

2021 ◽  
Vol 892 ◽  
pp. 99-106
Author(s):  
Romaynoor Ismy ◽  
Husaini ◽  
M. Saleh Sofyan ◽  
M. Isya
Keyword(s):  
Experimental Method ◽  
Vertical Axis ◽  
Flexible Pavement ◽  
Asphalt Mixtures ◽  
Wire Mesh ◽  
Flexural Test ◽  
Mesh Placement ◽  
Base Course ◽  
Flexural Resistance ◽  
Resistance Value

Flexural resistance is the ability of a specimen to withstand force in two pedestals with vertical axis until it is broken. Flexible pavement is a type of pavement which is very dependent with pavement course underneath. The dependency of flexible pavement in both base course and subgrade makes this pavement difficult to apply in unstable soil. Using wire mesh course as reinforcement is considerably able to raise the flexural resistance. This study is aimed to analyze flexural resistance value in hot mix by using wire mesh course as reinforcement. The study is conducted by applying experimental method with designing four types of wire mesh laying models in hot mix using three points flexural test equipment. Based on the study result, it is found that hot mix with wire mesh laying 30 mm from specimen surface is the best model type with 291,85 KN flexural resistance value with 8 mm of deflection depth. In this laying, it can be concluded that wire mesh course can raise up the flexural resistance up to 35,41% compared to the hot mix without wire mesh course.

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.

Experimental Analysis of Dynamic Modulus and Phase Angle of High Modulus Asphalt Mixture

2011 ◽  
Vol 243-249 ◽  
pp. 4220-4225
Author(s):  
Rui Bo Ren ◽  
Li Tao Geng ◽  
Li Zhi Wang ◽  
Peng Wang
Keyword(s):  
Phase Angle ◽  
Dynamic Modulus ◽  
Asphalt Mixture ◽  
Performance Testing ◽  
Asphalt Mixtures ◽  
Testing System ◽  
High Modulus ◽  
Temperature Performance ◽  
Different Temperatures ◽  
Confining Pressures

To study the mechanical properties of high modulus asphalt mixtures, dynamic modulus and phase angle of these two mixtures are tested with Simple Performance Testing System under different temperatures, loading frequencies and confining pressures. Testing results show the superiority of high modulus asphalt mixture in aspect of high temperature performance. Furthermore, the changing rules of dynamic modulus and phase angle are also discussed.

Utilization of water-quenching blast furnace slag as alternative filler in asphalt mastic

2020 ◽  
Vol 47 (9) ◽  
pp. 1075-1083
Author(s):  
Jianyou Huang ◽  
Xiangyang Xing ◽  
Jun Cai ◽  
Jianzhong Pei ◽  
Rui Li ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Complex Modulus ◽  
Asphalt Mixtures ◽  
Water Quenching ◽  
Creep Recovery ◽  
Chemical Compositions ◽  
Asphalt Mastic ◽  
Asphalt Mastics ◽  
Furnace Slag

Water-quenching blast furnace slag as a by-product of the iron production has caused serious environmental concerns. This paper tried to investigate the feasibility of the blast furnace slag filler (WBFSF) used as an alternative filler to replace the limestone filler (LF) in asphalt mixtures. Specifically, the chemical compositions, morphology characteristics, phase distributions, and thermal properties of two fillers were studied; then rheological properties of asphalt mastics in four filler–asphalt ratios were further studied by the rotational viscosity, temperature sweep, temperature–frequency–sweep (T-f-sweep), and multiple stress creep recovery (MSCR) test. The results show that WBFSF has a larger specific surface area and better-developed mesopores compared with LF. WBFSF asphalt mastic presents a larger complex modulus and a smaller phase angle. Moreover, the MSCR results show that WBFSF improves the elastic recovery and rutting resistance of asphalt mastics. Therefore, WBFSF presents great potential to be used as an alternative filler in asphalt mixtures.

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