scholarly journals Structural Evaluation of Full-Depth Flexible Pavement Using APT

2021 ◽  
Author(s):  
Tommy E. Nantung ◽  
Jusang Lee ◽  
John E. Haddock ◽  
M. Reza Pouranian ◽  
Dario Batioja Alvarez ◽  
...  
Keyword(s):  
Asphalt Concrete ◽  
Prediction Models ◽  
Design Method ◽  
Permanent Deformation ◽  
Pavement Design ◽  
Asphalt Pavements ◽  
Statistical Parameters ◽  
Significant Difference ◽  
Pavement Structures ◽  
Rutting Behavior

The fundamentals of rutting behavior for thin full-depth flexible pavements (i.e., asphalt thickness less than 12 inches) are investigated in this study. The scope incorporates an experimental study using full-scale Accelerated Pavement Tests (APTs) to monitor the evolution of each pavement structural layer's transverse profiles. The findings were then employed to verify the local rutting model coefficients used in the current pavement design method, the Mechanistic-Empirical Pavement Design Guide (MEPDG). Four APT sections were constructed using two thin typical pavement structures (seven-and ten-inches thick) and two types of surface course material (dense-graded and SMA). A mid-depth rut monitoring and automated laser profile systems were designed to reconstruct the transverse profiles at each pavement layer interface throughout the process of accelerated pavement deterioration that is produced during the APT. The contributions of each pavement structural layer to rutting and the evolution of layer deformation were derived. This study found that the permanent deformation within full-depth asphalt concrete significantly depends upon the pavement thickness. However, once the pavement reaches sufficient thickness (more than 12.5 inches), increasing the thickness does not significantly affect the permanent deformation. Additionally, for thin full-depth asphalt pavements with a dense-graded Hot Mix Asphalt (HMA) surface course, most pavement rutting is caused by the deformation of the asphalt concrete, with about half the rutting amount observed within the top four inches of the pavement layers. However, for thin full-depth asphalt pavements with an SMA surface course, most pavement rutting comes from the closet sublayer to the surface, i.e., the intermediate layer. The accuracy of the MEPDG’s prediction models for thin full-depth asphalt pavement was evaluated using some statistical parameters, including bias, the sum of squared error, and the standard error of estimates between the predicted and actual measurements. Based on the statistical analysis (at the 95% confidence level), no significant difference was found between the version 2.3-predicted and measured rutting of total asphalt concrete layer and subgrade for thick and thin pavements.

Full-Scale Evaluation of Relatively Thin Airfield Pavements

2020 ◽  
Vol 2674 (10) ◽  
pp. 658-669
Author(s):  
W. Jeremy Robinson ◽  
Jeb S. Tingle ◽  
Carlos R. Gonzalez
Keyword(s):  
Asphalt Concrete ◽  
Test Section ◽  
Concrete Surface ◽  
Full Scale ◽  
Test Items ◽  
Pavement Structures ◽  
Base Course ◽  
And Performance ◽  
Rutting Behavior ◽  
Aggregate Base

A full-scale airfield pavement test section was constructed and trafficked by the U.S. Army Engineer Research and Development Center (ERDC) to evaluate the performance of relatively thin airfield pavement structures. The test section consisted of four test items that included three asphalt pavement thicknesses and two different aggregate base courses. The test items were subjected to simulated aircraft traffic to evaluate their response and performance to realistic aircraft loads. Rutting behavior, instrumentation response, and falling weight deflectometer response were monitored at selected traffic intervals. It was found that the performance of the airfield pavement sections were most sensitive to aggregate base course properties, where a 50% reduction in base course strength resulted in a 99% reduction in allowable passes. The data suggested that when sufficient asphalt thickness is not provided, the failure mechanism shifted from subgrade failure to base course failure, particularly at higher subgrade CBR values. In addition, the number of aircraft passes sustained was less than that predicted by current Department of Defense (DOD) methods that include assumptions of a high-quality aggregate base and a minimum asphalt concrete thickness. The results of this study were used to extend existing DOD pavement design and evaluation techniques to include the evaluation of airfield pavement sections that do not meet the current criteria for aggregate base quality and minimum asphalt concrete surface thickness. These performance data were used to develop a new base failure design curve using existing stress-based design criteria.

Design of Granular Pavements

2003 ◽  
Vol 1819 (1) ◽  
pp. 194-200 ◽  
Author(s):  
Greg Arnold ◽  
David Hughes ◽  
Andrew R. Dawson ◽  
Des Robinson
Keyword(s):  
Stress State ◽  
Design Method ◽  
Permanent Deformation ◽  
Design Criterion ◽  
Pavement Design ◽  
Performance Criteria ◽  
Crushed Rock ◽  
Long Distance ◽  
High Quality ◽  
Final Thickness

The use of high-quality quarried crushed rock aggregates is generally required to comply with current specifications for unbound granular materials (UGMs) in pavements. The source of these high-quality materials can be a long distance from the site, resulting in high transportation costs. The use of more local sources of marginal materials or the use of secondary aggregates is not allowed if they do not fully comply with existing specifications. These materials can, however, be assessed for their suitability for use in a pavement by considering performance criteria such as resistance to permanent deformation and degradation instead of relying on compliance with inflexible specifications. The final thickness of the asphalt cover and the pavement depth are governed by conventional pavement design methods, which consider the number of vehicle passes, subgrade strength, and some material property, commonly the California bearing ratio or resilient modulus. A pavement design method that includes as a design criterion an assessment of the resistance to deformation of a UGM in a pavement structure at a particular stress state is proposed. The particular stress state at which the aggregate is to perform in an acceptable way is related to the in situ stress, that is, the stress that the aggregate is anticipated to experience at a particular depth in the pavement. Because the stresses are more severe closer to the pavement surface, the aggregates should be better able to resist these stresses the closer they are laid to the surface in the pavement. This method was applied to two Northern Ireland aggregates of different quality (NI Good and NI Poor). The results showed that the NI Poor aggregate performed at an acceptable level with respect to permanent deformation, provided that a minimum of 70 mm of asphalt cover was provided. It was predicted that the NI Good material would require 60 mm of asphalt cover.

scholarly journals SUGGESTING A SIMPLE DESIGN METHOD FOR COLD RECYCLED ASPHALT MIXES WITH ASPHALT EMULSION

2017 ◽  
Vol 23 (7) ◽  
pp. 966-976 ◽  
Author(s):  
Bahador BAZRAFSHAN MOGHADAM ◽  
Hamid FARHAD MOLLASHAHI
Keyword(s):  
Design Method ◽  
Mix Design ◽  
Asphalt Pavements ◽  
Asphalt Emulsion ◽  
Recycled Asphalt ◽  
Moisture Susceptibility ◽  
Asphalt Mixes ◽  
Reclaimed Asphalt ◽  
Significant Difference ◽  
Emulsified Asphalt

Although there are typical and well-known standard methods for designing hot mix asphalt in the world, there is no unique design method for cold recycled asphalt mixes. The current methods are mainly local or even dependent on technology owners due to the diversity of materials and qualitative control limitations. Currently, most of the design methods are based on 4 inch mold. The major problem of these methods is that in the mix design, the effect of aggre­gates larger than 25 mm is neglected, while this size of aggregates is used in the recycling projects. Therefore, there is a significant difference between in-situ and laboratory mix behaviors. So, 6-inch mold is used. In this study, a simple mix design has been obtained for reclaimed asphalt pavements (RAP) considering the different amount of emulsified asphalt, Portland cement, three gradations, moisture contents, temperatures, and curing times. For this reason, 315 samples were prepared. The results show that the mixes with aggregates larger than 25 mm have a significant difference with 25 mm and smaller aggregates sizes in terms of mechanical properties and moisture susceptibility. Therefore, 6-inch molds should be used for RAP materials that are larger than 25 mm in the mix design.

scholarly journals Sensitivity Analysis of Rigid Pavement Design Based on Semi-Empirical Methods: Romanian Case Study

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 168
Author(s):  
Costel Pleșcan ◽  
Elena-Loredana Pleșcan ◽  
Mariana D. Stanciu ◽  
Marius Botiș ◽  
Daniel Taus
Keyword(s):  
Input Data ◽  
Design Method ◽  
Design Procedure ◽  
Plain Concrete ◽  
Empirical Method ◽  
Traffic Volume ◽  
Pavement Design ◽  
Mountainous Area ◽  
Rigid Pavement ◽  
Pavement Structures

Due to the intensive process of road construction or rehabilitation of pavement caused by an increase in traffic volume, in the field of rigid pavement design and research in Romania, we can say that there is a need to improve the design method. In the last decade, more and more researchers have been concerned about climate change and the increase in traffic volume; hence, there is a need for a renewal of the climatological, as well as traffic, databases because these are part of the input data for the design process. The design method currently used in Romania for jointed plain concrete pavement design is NP081/2002. The limitation of the data and the lack of lifetime estimation of structural and functional performance are the main aspects that need to be addressed in the new design procedure. The Mechanistic–Empirical Pavement Design (MEPDG) method offers the possibility of the design of pavement structures by estimating the structural and functional performances. This paper aims to obtain a comparative study of these two methods for the analysis of the input data collected from the field corresponding to the three failure criteria, while the symmetry of the characteristics of the material and their asymmetrical thicknesses are compared, thus contributing to the design of viable and long-lasting pavement structures using a rigid pavement with the specific characteristics of the mountainous area in northeastern Romania on the national road DN17 Suceava—Vatra Dornei. The novelty of this study consists of the implementation of the mechanistic–empirical method MEPDG instead of the old NP081/2002 method used in Romania.

Analysis of Perpetual Asphalt Pavement Response under Heavy Loads in Northeast Area of China

2013 ◽  
Vol 838-841 ◽  
pp. 1203-1215
Author(s):  
Deng Wen Zhou ◽  
Rong Jin Wang
Keyword(s):  
Finite Element ◽  
Contact Area ◽  
Asphalt Concrete ◽  
Asphalt Pavement ◽  
Asphalt Pavements ◽  
Rigid Base ◽  
Characteristic Finite Element ◽  
Pavement Structures ◽  
Heavy Loads ◽  
High Traffic Volume

Severe rutting, cracks and moisture damage are presented on conventional semi-rigid base asphalt pavements not long after completed in China. This phenomenon indicates that conventional philosophy on pavement design could not meet more and more frequent and heavy vehicle. With high structural capacity for high traffic volume and heavy loads, the Perpetual Asphalt Pavements (PAPs) solve those problems well. Meanwhile they need minimal or no major structural rehabilitation and/or reconstruction exercises in their life, which ensures low user-delay. Three PAPs, including semi-rigid base asphalt pavement, flexible base asphalt pavement, and combined base asphalt pavement, are put forward for the northeast area in China considering its climate, traffic characteristic. Finite element method is utilized to analyze response of PAPs under heavy loads. Two key factors, i.e. tensile horizontal strains at the bottom of asphalt layers and compressive vertical strains are investigated. Also the capacities of the structures on bearing overloading are estimated. Four types of wheel and axle, including single axle and single tire, single axle and dual tires, dual axles and dual tires, and tri axles and dual tires are adopted in finite element models. The shapes of tire-pavement contact area are either circular or rectangular to simulate standard load or overloading respectively. When rectangular shapes are adopted, the contact area sizes and the distribution of pressure are varied. Conventional asphalt concrete and high modulus asphalt concrete are adopted. Simulations are done. The competences of the three pavement structures on fulfilling long lives are evaluated.

scholarly journals An overview of asphalt pavement design for streets and roads

2020 ◽  
Author(s):  
Luis Ricardo Vásquez-Varela ◽  
Francisco Javier García-Orozco
Keyword(s):  
Design Method ◽  
Design Procedure ◽  
Pavement Design ◽  
Asphalt Pavements ◽  
Analysis And Design ◽  
Incremental Design ◽  
History Of ◽  
Design Factors ◽  
Geotechnical Problems ◽  
Proper Analysis

Pavements are geotechnical problems; consequently, a geotechnical framework is useful to describe their constitutive elements. The design of asphalt pavements for streets and roads evolved from empiric to mechanistic-empiric (M-E) procedures throughout the 20th century. The mechanistic-empiric method, based on layered elastic theory, became a common practice with the publication of separate procedures by Shell Oil, Asphalt Institute, and French LCPC, among others. Since its origin, the M-E procedure can consider incremental pavement design but, only until the beginning of the 21st century, the computational power became available to practicing engineers. American MEPDG represents the state-of-the-art M-E incremental design procedure with significant advantages and drawbacks, the latter mainly related to the extensive calibration activities required to assure a proper analysis and design according to subgrade, climate, and materials at a particular location and for an intended level of reliability. Perpetual pavements are a subset of M-E designed pavements with a proven history of success for the particular conditions where they are warranted. No design method, either the most straightforward empirical approach or the most elaborated incremental mechanistic one, is appropriate without proper knowledge about the fundamental design factors and calibration of the performance models for each distress mode upon consideration.

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