Performance Prediction of Louisiana Accelerated Loading Facility Test Sections

2000 ◽  
Vol 1716 (1) ◽  
pp. 108-115
Author(s):  
Ludfi Djakfar ◽  
Freddy L. Roberts
Keyword(s):  
Performance Prediction ◽  
Field Performance ◽  
Fatigue Cracking ◽  
Surface Cracking ◽  
Unbound Granular Materials ◽  
Soil Cement ◽  
Different Types ◽  
Reasonable Prediction ◽  
Transportation Research ◽  
Unbound Granular Material

Using the accelerated loading facility (ALF), the Louisiana Transportation Research Center recently conducted an accelerated pavement test of nine test sections that consisted of the same asphalt wearing course but had different types and thicknesses of crushed stone and soil cement bases and subbases. One of the aims of the project was to compare observed field performance with that predicted with use of the VESYS 3A-M mechanistic prediction model, which predicts the development of rutting, cracking, and roughness, along with serviceability [present serviceability index (PSI)] over time. It was found that VESYS provided a reasonable prediction of observed rutting and PSI—albeit an underestimation—but a poor estimate of surface cracking. This was probably related to the fact that the observed cracking was due to shrinkage of the soil cement rather than fatigue cracking under the load, and also to the fact that VESYS is generally used to model unbound granular materials that have a modulus no greater than 690 MPa (100 ksi). The modulus of soil cement material tested by ALF was 105 MPa (150 ksi) and its behavior under load would be different from that of an unbound granular material. More research is needed into the behavior of soil cement bases, their influence on the cracking of asphalt surfacings, and the most appropriate input into VESYS to model this behavior.

Incorporation of Endurance Limit in the Mechanistic-Empirical Flexible Perpetual Pavement Design

2018 ◽  
Vol 2672 (40) ◽  
pp. 108-121 ◽  
Author(s):  
Sheng Hu ◽  
Sang-Ick Lee ◽  
Lubinda F. Walubita ◽  
Fujie Zhou ◽  
Tom Scullion
Keyword(s):  
Endurance Limit ◽  
Design Method ◽  
Field Performance ◽  
Fatigue Cracking ◽  
Climatic Conditions ◽  
Influential Factors ◽  
Pavement Design ◽  
Design System ◽  
Viscoelastic Continuum Damage ◽  
Perpetual Pavement

In recent years, there has been a push toward designing long-lasting thick hot mix asphalt (HMA) pavements, commonly referred to as a perpetual pavements (PP). For these pavements, it is expected that bottom-up fatigue cracking does not occur if the strain level is below a certain limit that is called the HMA fatigue endurance limit (EL). This paper proposed a mechanistic-empirical PP design method based on this EL concept. The ELs of 12 HMA mixtures were determined using simplified viscoelastic continuum damage testing and the influential factors were comparatively investigated. It was found that HMA mixtures seem to have different EL values based on mix type and test temperatures. There is not just a single EL value that can be used for all mixtures. Thus, default EL criteria for different mixtures under different climatic conditions were developed and incorporated into the Texas Mechanistic-Empirical Flexible Pavement Design System (TxME). As a demonstration and case study, one Texas PP test section with weigh-in-motion traffic data was simulated by TxME. The corresponding TxME inputs/outputs in terms of the PP structure, material properties, traffic loading, environmental conditions, and ELs were demonstrated. The corresponding TxME modeling results were consistent with the actual observed field performance of the in-service PP section.

Design, Construction, and Analysis of Pavements Using Accelerated Loading Facility

1997 ◽  
Vol 1590 (1) ◽  
pp. 73-79
Author(s):  
Freddy L. Roberts ◽  
Louay N. Mohammad ◽  
Ludfi Djakfar ◽  
Amar Raghavendra
Keyword(s):  
Fatigue Cracking ◽  
Primary Response ◽  
Performance Data ◽  
Test Facility ◽  
Response Analysis ◽  
Damage Prediction ◽  
Testing Facility ◽  
Short Period ◽  
Transportation Research ◽  
Design Construction

The Louisiana Transportation Research Center has recently completed the construction of a full-scale pavement test facility using the accelerated loading facility (ALF) machine. This facility contains nine pavement test sections, 12-m (38-ft) long and 3.66-m (12-ft) wide that are loaded by the ALF machine with loads ranging from 34.71 to 111.25 kN (7,800 to 25,000 lbf) on a dual-tire assembly. The advantage of this testing facility is its ability to cause a pavement to fail in a short period of time. In addition, the data acquisition methods and instrumentation used in this testing facility allow researchers to obtain reliable and representative performance data. The first test section has been loaded to failure and a preliminary analysis of the data is completed. VESYS 3A-M, a microcomputer version of the VESYS series, has been selected for the analysis due to its ability to predict damage and its flexibility. The analysis consists of the primary response analysis to determine strains, stresses, and deflection of the pavement and damage-prediction modeling that includes rutting, fatigue cracking, and roughness. The analysis was conducted by comparing the data obtained from field with that predicted by VESYS 3A-M. The performance data obtained from the field include fatigue cracking, rutting, and roughness. The analysis showed that VESYS 3A-M outputs are in good agreement with those obtained from the field.

Development of Performance-Related Specifications for Hot-Mix Asphalt Pavements Through WesTrack

1997 ◽  
Vol 1575 (1) ◽  
pp. 85-91 ◽  
Author(s):  
Stephen B. Seeds ◽  
Rudramunniyappa Basavaraju ◽  
Jon A. Epps ◽  
Richard M. Weed
Keyword(s):  
Performance Prediction ◽  
Prediction Models ◽  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Fatigue Cracking ◽  
Primary Objective ◽  
Pavement Performance ◽  
Void Content ◽  
Target Values ◽  
Pavement Performance Prediction

The primary objective of the FHWA-sponsored WesTrack project is to further the development of performance-related specifications for hotmix asphalt construction. This objective is being achieved, in part, through the accelerated loading of a full-scale test track facility in northern Nevada. Twenty-six hot-mix asphalt test sections constructed to meet the criteria set forth in a statistically based experiment design are providing performance data that will be used to improve existing (or develop new) pavement performance prediction relationships that better account for the effects that “off-target” values of asphalt content, air-void content, and aggregate gradation have on such distress factors as fatigue cracking, permanent deformation, roughness, raveling, and tirepavement friction. The concept of the planned new performance-related specification and how it will incorporate the modified pavement performance prediction models are described. The current plan for assessing contractor pay adjustments (i.e., penalties and bonuses) based on data collected from the as-constructed pavement is also discussed.

Field performance of top-down fatigue cracking for warm mix asphalt pavements

2016 ◽  
Vol 20 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Shenghua Wu ◽  
Haifang Wen ◽  
Weiguang Zhang ◽  
Shihui Shen ◽  
Louay N. Mohammad ◽  
...  
Keyword(s):  
Field Performance ◽  
Fatigue Cracking ◽  
Warm Mix Asphalt ◽  
Asphalt Pavements ◽  
Top Down

Matched-Field Performance Prediction with Model Mismatch

2016 ◽  
Vol 23 (4) ◽  
pp. 409-413
Author(s):  
Yann Le Gall ◽  
Francois-Xavier Socheleau ◽  
Julien Bonnel
Keyword(s):  
Performance Prediction ◽  
Field Performance ◽  
Model Mismatch

What types of grain boundaries can be passed through by persistent slip bands?

2003 ◽  
Vol 18 (5) ◽  
pp. 1031-1034 ◽  
Author(s):  
Z. F. Zhang ◽  
Z. G. Wang ◽  
J. Eckert
Keyword(s):  
Grain Boundaries ◽  
Large Angle ◽  
Fatigue Cracking ◽  
Stress Axis ◽  
Slip Systems ◽  
Slip Bands ◽  
Persistent Slip Bands ◽  
Different Types ◽  
The Difference ◽  
Intergranular Fatigue Cracking

Three typical interactions of persistent slip bands (PSBs) with different types of grain boundaries (GBs) were investigated and analyzed in fatigued copper crystals. The results show that PSBs cannot transfer through all types of large-angle GBs, regardless of their orientation with respect to the stress axis. Secondary slip was often observed near the GBs, leading to strain incompatibility. When the slip systems of the two adjacent crystals are coplanar, the transmission of a PSB across a GB strongly depends on the slip directions of the two adjacent crystals. It was found that only the low-angle GBs can be passed through by PSBs, and accordingly they are insensitive to intergranular fatigue cracking. For a special copper bicrystal with coplanar slip systems, the ladderlike dislocation arrangements within the adjacent PSBs become discontinuous and a dislocation-affected-zone appears near the GB due to the difference in the slip direction of the two adjacent crystals. Therefore, the necessary conditions for the transmission of a PSB across a GB are that the neighboring grains have a coplanar slip system and identical slip directions.

scholarly journals Centrifugal Compressor Testing Experience and Practice

1982 ◽  
Author(s):  
R. H. Meier ◽  
C. S. Rhea
Keyword(s):  
Natural Gas ◽  
Centrifugal Compressor ◽  
Performance Testing ◽  
Field Performance ◽  
Field Testing ◽  
Aerodynamic Performance ◽  
Reasonable Accuracy ◽  
Centrifugal Compressors ◽  
Factory Test ◽  
Different Types

Experience with factory and field performance testing of centrifugal compressors in natural gas service is presented. The ability of different types of factory test arrangements to closely predict future field performance is compared. Instrumentation requirements for achievement of reasonable accuracy in field testing are defined and discussed. Major aspects of mechanical and aerodynamic performance testing are addressed.

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