Pavement Design Parameters Research Articles

A Method for Customizing Flexible Pavement Design Parameters for EDCF-Funded Projects in Asia

A Method for Customizing Flexible Pavement Design Parameters for EDCF-Funded Projects in Asia

Development of an artificial neural network model to predict subgrade resilient modulus from continuous deflection testing

The subgrade resilient modulus is an important parameter in pavement analysis and design. However, available non-destructive testing devices such as the falling weight deflectometer (FWD) have limi...

A mechanistic approach to evaluate the potential of the debonding distress in asphalt pavements

The debonding distress in asphalt pavement structures is a critical problem that affects the performance of asphalt concrete pavements. It occurs at the layer interface due to the poor bond quality between adjacent asphalt concrete layers and/or when stresses at the layer interface exceed the strengths of the material at the interface. The debonding of the adjacent layers, especially the top surface layer of an asphalt pavement, is a contributing factor to the premature cracking of pavements. Hence, the debonding distress can lead to a reduction in the life of the pavement. This paper presents an analytical and experimental framework to evaluate the potential for debonding at the layer interface of asphalt concrete pavements. Computational analysis was performed to determine the critical stress and strain states in layered asphalt pavements under moving vehicle loads using the Layered ViscoElastic pavement analysis for Critical Distresses (LVECD) computer program developed at North Carolina State University. This computational analysis enables a greater understanding of the critical stress that is involved in debonding and the ways that such stress is affected by pavement design parameters and environmental conditions. In addition, a prediction model was developed that can determine the shear bond strength at the interface of asphalt concrete layers with different tack coat materials at various temperatures, loading rates and normal confining stresses. The systematic and mechanistic framework developed in this study employs the maximum shear ratio concept as a shear failure criterion and provides a tool to evaluate the effects of various loading, environmental and pavement factors on the debonding potential of asphalt pavements. The overall advantages of the mechanistic framework and approach using the LVECD analysis tool will help lead to better understanding of the debonding mechanism, proper selection of the tack coats, and economic benefit in highway pavement maintenance and rehabilitation costs.

Numerical evaluation of pavement design parameters for the fatigue cracking and rutting performance of asphalt pavements

Over recent years, significant research has been conducted to investigate ways to predict fatigue cracking and permanent deformation (rutting), which are two common distresses found in asphalt pavements. These distresses are affected by material properties, environmental conditions, and the pavement’s structure. This paper investigates common pavement design parameters, including surface mixture type, base layer thickness, base layer type, sub-base layer thickness, and an anti-frost layer, with regard to the asphalt pavement performance of the Korea Expressway Corporation (KEC) test road. Test roads are often regarded as the most realistic tools for evaluating the effects of various parameters because they are subjected to real traffic and environmental factors. The KEC test road is 7.7 km long and was constructed with the aim of developing a Korean mechanistic-empirical pavement design guide. According to the findings, the surface layer type, base layer thickness, and base layer material type were found to affect the fatigue cracking and rutting performance, whereas the sub-base thickness and anti-frost layer were found not to affect the amount of distress significantly. The newly developed ‘layered viscoelastic pavement analysis for critical distresses’ (LVECD) program was able to capture the effects of the changes in the aforementioned parameters on the amount of cracking and rut depths. Reasonable agreement was found between the LVECD predictions and the field distress measurements. However, it remains necessary to develop a laboratory-to-field transfer function in order to obtain more accurate field performance predictions.

Determining the Relative Importance of Parameters Affecting Concrete Pavement Thickness

Spending costs in construction of road pavements has turned this subject into one of the significant points in transportation infrastructure of countries. Concrete slabs consider as a paving method with ability of reducing the rehabilitation needs. Therefore, to manage costs and optimize the thickness of concrete pavements, recognizing the amount of determinative factors’ influence will be required. A study with the aim of determining the influence of traffic parameters, type of subgrade soil and the base layer thickness on the concrete pavement slab thickness can provide the choice of best concrete pavement design. For this purpose, the PCASE software has been used in this paper to construct sufficient number of numerical examples, 288 specimens, with taking into account the number of equivalent single axle, the subgrade modulus of concrete pavement construction place and the base layer thickness. These samples are considered as the basis of training and testing an artificial neural network and the level of pavement design parameters importance is relatively determined on the results of optimal neural network. The method used in this paper for calculating the relative importance of each parameter involved in the concrete pavement thickness indicates that the parameters of base layer thickness and the number of equivalent single axle have the lowest and highest level of influence, with the values of about 21 and 42 percent, respectively. The obtained results are also compatible with concepts and structural features of concrete pavements.

MEPDG Analysis on Relationship between Design Inputs and Performance of Asphalt Pavements

The main objective of this research is to explore the quantitative relationship between the pavement design parameters (structural layer thickness, voids, aggregate gradation and temperatures) and pavement performance parameters (rutting, cracking and IRI). The Mechanistic-Empirical Pavement Design Guide (MEPDG) was used and the analysis was performed on pavements under three temperature conditions namely the intermediate temperature zone (Zhengzhou in Henan Province), the low temperature zone (MOHE in Heilongjiang province) and the high temperature zone (Turpan in Xinjiang province). It was observed that 1) Pavement performances (rutting and cracking) were significantly impacted by layer thickness values until the values were larger than 14 inch; 2) Air void content influenced on not only predicted pavement rutting but also the thermal cracking.

Rational approach for tropical pavement design using life-cycle principles: case study of Ghana

Fundamental differences exist with respect to soil types formed under temperate and tropical climatic conditions. Their use for road pavement designs will require methods which take into account their behaviour in these distinct climate zones. Road pavement design with the respective soil material will therefore require different approaches. The adoption of temperate-based empirical pavement design systems for tropical pavement design parameters is inappropriate because the underlying assumptions do not reflect tropical conditions. At the other extreme of pavement design is the mechanistic approach. A hybrid method is the mechanistic-empirical (ME) method where empirical models are used to fill in the gaps between the mechanics and the performance of the pavement. This paper presents a rational approach in the application of M-E pavement design principles to evolve a design framework which takes into account tropical conditions using Ghana as a case study.

Effect of pavement design parameters on the behaviour of orthotropic steel bridge deck pavements under traffic loading

This study evaluated the effect of the pavement design parameters on the behaviour of orthotropic steel bridge deck pavements under traffic loading using a three-dimensional finite element model. Four types of paving materials were considered in this analysis: polymer concrete, epoxy asphalt concrete, polymer-modified stone mastic asphalt concrete and mastic asphalt concrete. The maximum transverse tensile strain was developed at the bottom of the pavement under a tyre of dual tyres or on top of the pavement between two tyres. From the sensitivity analysis, better interface bonding between the deck plate and pavement led to a significant enhancement of bottom-up fatigue cracking resistance, especially for 40-mm-thick pavements. As pavement temperature increased from − 20 to 60°C, critical tensile strain increased significantly, and corresponding locations moved from the bottom to the top of the deck pavement.

Viscoelastic-Plastic Model of Asphalt-Roller Interaction

There are several factors that influence the quality of an asphalt pavement. While pavement design, material selection, and environmental parameters play a big role in the quality and useful life of the pavement, adequate quality control during the compaction process is also necessary to achieve the desired quality. Previous research has addressed the effect of material selection, pavement design and construction, and environmental factors on the long-term performance of asphalt pavement. However, very little work has been done to address the effect of the compaction process on the quality of pavement. A proper understanding of the interaction between the roller and an asphalt pavement is necessary to develop closed-loop control algorithms for intelligent compaction (IC) of asphalt pavements. While several variants of IC techniques are being offered in the market, there is a need for an accurate dynamical model of the compaction process to validate these methods. In this paper, a viscoelastic-plastic (VEP) model of an asphalt pavement is developed that can effectively represent the dynamical properties of the asphalt mat during compaction. This model is then integrated with a mathematical model of a vibratory compactor to study the response of the coupled system during compaction. The VEP model is based on Burger’s model and is used to represent the dynamical properties of the asphalt pavement. The parameters of the model are first estimated from the dynamic modulus master curves of the asphalt mix. These parameters are then continuously updated to accurately represent the properties of the asphalt mat during compaction. Detailed mathematical equations are developed that relate the changes in the asphalt mat to the vibratory response of the roller during compaction. Numerical simulation of the VEP model shows that the response of the coupled system can be used to study the compaction of asphalt pavements. Comparison of the simulation results with data gathered during construction of asphalt pavements indicate that this model could serve as a theoretical foundation for intelligent compaction of asphalt pavement.

Strain response of hot-mix asphalt overlays in jointed plain concrete pavements due to reflective cracking

Reflective cracks appear in asphalt overlays placed on top of a concrete pavement above the locations of joints and cracks in the concrete slab. This paper presents the results of a finite element study on the response at the bottom of the HMA overlay. The effects of subgrade and subbase strengths, vehicle speed, overlay thickness, and pavement temperature are investigated in order to identify the parameters involved in the deterioration of the overlay. An extrapolation of the strain history curve for various pavement design parameters is presented to estimate the number of load repetitions that lead to bottom–up crack initiation.

Characterisation, Analysis and Design of Hydrated Cement Treated Crushed Rock Base as a Road Base Material in Western Australia

Hydrated Cement Treated Crushed Rock Base (HCTCRB) is widely used as a base course in Western Australian pavements. HCTCRB has been designed and used as a basis for empirical approaches and in empirical practices. These methods are not all-encompassing enough to adequately explain the behaviour of HCTCRB in the field. Recent developments in mechanistic approaches have proven more reliable in the design and analysis of pavement, making it possible to more effectively document the characteristics of HCTCRB. The aim of this study was to carry out laboratory testing to assess the mechanical characteristics of HCTCRB. Conventional triaxial tests and repeated load triaxial tests (RLT tests) were performed. Factors affecting the performance of HCTCRB, namely hydration periods and the amount of added water were also investigated. It was found that the shear strength parameters of HCTCRB were 177 kPa for cohesion (c) and 42° for the internal friction angle (). The hydration period, and the water added in this investigation affected the performance of HCTCRB. However, the related trends associated with such factors could not be assessed. All HCTCRB samples showed stress-dependency behaviour. Based on the stress stages of this experiment, the resilient modulus values of HCTCRB ranged from 300 MPa to 1100 MPa. CIRCLY, a computer program based on the multi-layer elastic theory was used in the mechanistic approach to pavement design and analysis, to determine the performance of a typical pavement model using HCTCRB as a base course layer. The mechanistic pavement design parameters for HCTCRB as a base course material were then introduced. The analysis suggests that the suitable depth for HCTCRB as a base layer for WA roads is at least 185 mm for the design equivalent standard axle (ESA) of 10 million.

Impact of Subgrade Resilience Modulus on Heavy Load Asphalt Pavement Mechanical Properties

Subgrade resilience modulus is an important mechanical parameter in pavement design. It will directly influence the design result of pavement structure. Using BISAR3 of SHELL design method, the impacts of subgrade resilience modulus on pavement surface deflection, base and subbase bottom tensile stress, surface layer bottom tensile stress of the heavy load asphalt pavement structure were analyzed. And the influencing laws were analyzed, too. The results show that the mechanical and deforming characteristics of heavy load asphalt pavement were influnced significantly by subgrade resilience modulus. With the increasing of subgrade resilience modulus, the pavement surface deflection, base bottom tensile stress would significantly decrease, and fatigue life would be improved.

Reliability Analysis of Asphalt Pavement Structure Based on Three-Dimensional Finite Element

The design of asphalt pavements in china is currently based on the multilayered elastic method, which is analytical in nature and yields stresses, strains, and deflections in the pavement system for a particular loading condition and pavement geometry, which are compared with established failure criteria to determine the performance of the given pavement. This design approaches is deterministic. In this paper, typical asphalt pavement structure reliability analysis was performed in which factors that affect pavement reliability regarded as input random , pavement surface deflection, layers of bottom stress and limit state function regarded as output variables , by reliability tool infinite element analysis, base on Monte Carlo’s Latin hypercube sampling method.At last the paper pertinently offered decision basis for improve the reliability of pavement structure and important reference values for drafting and selecting of asphalt pavement design parameters through calculating the reliability of pavement structure, sensitivity analysis of the design parameters is made.

Analysis of Influence Factors of Temperature Stress for Open-Graded Large Stone Asphalt Mixes of Asphalt Pavement

The reflective cracking is one of the main damages of semi-rigid base asphalt pavement and rigid base asphalt pavement, how to control its emergence and development is still a major problem for road engineering. At present, researches on mechanical behavior of Open-graded Large Stone asphalt Mixes (OLSM) in China almost remain in the test road observations, very few study it from the point of the finite element theory. Aiming at this problem, a method of using OLSM as the cracking alleviation layer is proposed. The calculation principles of temperature stress of lean concrete base asphalt pavement with OLSM has been introduced, on the basis of the finite element software of ABAQUS, 3-D Finite Element Method (FEM) is used to analyze temperature stress for OLSM of asphalt pavement, the influence rule of pavement design parameters for its temperature stress has been discussed, and the theoretical basis for structural design of asphalt pavement with OLSM has been found.

Backcalculated and Laboratory-Measured Resilient Modulus Values

The resilient modulus ( MR) of roadbed soils is a necessary parameter in pavement design. The MR of roadbed soils is dependent on the soil type, water content, dry density, particle gradation, Atterberg limits, and stress states. Several procedures can be used for the determination of the MR: laboratory testing, backcalculation with nondestructive deflection testing (NDT) data, and correlations to other soil parameters such as the California bearing ratio, density, and water content. The first procedure is time-consuming and expensive and requires substantial resources to cover the various roadbed soils under the road network. The second is relatively inexpensive and fast and can be designed to cover representative soils under the pavement network. The third procedure is approximate and may be used for the Level 2 design of the Mechanistic–Empirical Pavement Design Guide. The Michigan Department of Transportation (MDOT) sponsored a research project for the development of a systematic procedure to determine the MR values for all soil types encountered under the pavement network in the state of Michigan. The procedure includes laboratory testing of representative disturbed and undisturbed soil samples, NDT with the MDOT falling weight deflectometer, and developing correlations between the MR values obtained from the two tests and between the MR values and other soil parameters that can be obtained using simple tests. The developed correlation equations between the MR measured values and the other soil parameters are presented elsewhere, whereas the correlations between the laboratory-obtained and the backcalculated MR values are discussed in this paper.

Early-Life Performance of Cold-in-Place Pavement Recycling with Foamed Asphalt Technique

The cold-in-place recycling technique with foamed asphalt stabilization was used to rehabilitate a severely damaged, heavily trafficked highway, part of the Trans European Network. Lack of experience, at least as far as the performance of the aforementioned technique for heavy-duty pavements was concerned, was the main reason for the Greek Ministry of Public Works to undertake a field experiment incorporating semirigid and flexible pavements. To achieve this goal, a comprehensive monitoring and data analysis research study was performed; it concentrated on the falling weight deflectometer as a major tool for the in situ evaluation of early-life performance of the recycled pavement. In addition, as-built roughness and ground-penetrating radar measurements, accomplished with in situ material coring and related laboratory tests, were performed. The roughness data analysis raised several issues concerning the construction of the recycled layer. According to the deflection analysis, an improvement in the recycled pavement structural condition was observed during the early life. The foamed asphalt material of the semirigid pavement proved to be stiffer than that of the flexible pavement. Furthermore, significant differences between pavement design parameters and related in situ characteristics were obtained through the strain response analysis.

Calibration of Nonnuclear Density Gauge Data for Accurate In-Place Density Prediction

Hot-mix asphalt (HMA) density is an important acceptance quality characteristic, which involves in situ tests for quality control and assurance (QC/QA). Highway agencies have conventionally used nuclear density gauges or core samples for mat density. More recently, alternate nondestructive testing methods have been considered to replace current test methods. Nonnuclear density gauges offer rapid testing while eliminating safety risks and costs associated with radioactive license. Although agencies have evaluated them, they are not implemented in acceptance testing so far. Results are presented from a field evaluation of three nonnuclear density gauges—PaveTracker, PQI 300, and PQI 301—conducted on Wisconsin Department of Transportation (WisDOT) paving projects. The main goal was to evaluate the performance and effectiveness of non-nuclear gauges for use in QC/QA activities by WisDOT. The study involved field tests at 16 project sites and included 21 mix designs and a variety of mix design and pavement design parameters, such as aggregate type, nominal maximum aggregate size, layer thickness, design traffic, and base type. Density measurements were recorded at 30 test points at each site with one nuclear gauge and three nonnuclear gauges. Although the mean standard deviation values of the nonnuclear gauge data were less than those of the nuclear gauge measurements, a consistent bias was observed between the two data sets. This bias was adjusted by using a calibration factor to yield density predictions statistically the same as the nuclear gauge measurements. It is recommended that a calibration factor determined from 10 points by using a slope function be implemented for agency use. Further, daily calibration for each mix design is recommended when the project involves multiple paving days.

Evaluation of Pavement Slab Rocking and Pumping with Elevation Profile Data

A method is presented for estimating the amount of slab rocking and the amount of earth moved beneath a jointed concrete pavement as a result of slab rocking. The estimates are obtained with data from noncontact rapidly traveling profilers that collect surface elevation profiles along roadways at normal driving speeds without lane closure or traffic control costs. With profile data from FHWA Long-Term Pavement Performance (LTPP) General Pavement Study 3 (GPS-3) test sites, examples are provided to show how the apparent slab rocking and pumping volumes develop over time for most GPS-3 test sections that have shown significant faulting. The calculated pumping volume rate per equivalent single-axle load (ESAL) is shown to be relatively constant over time at these LTPP test sites. A preliminary linear regression predictive model for pumping rate per ESAL as a function of pavement design parameters is provided based on the test group of faulting GPS-3 pavements. This study indicates that pumping rate can be reduced with thicker and longer slabs and thicker layers of erosion-resistant base and subbase overlying erosion-susceptible subgrades. Slab lengths less than 15 ft (4.57 m) long appear noticeably more susceptible to rocking and pumping. Sites with high pumping rates typically have a combination of unusually large slabs locked in upward curvature and erosion-susceptible cross-section designs.

Evaluation of Pavement Slab Rocking and Pumping with Elevation Profile Data

A method is presented for estimating the amount of slab rocking and the amount of earth moved beneath a jointed concrete pavement as a result of slab rocking. The estimates are obtained with data from noncontact rapidly traveling profilers that collect surface elevation profiles along roadways at normal driving speeds without lane closure or traffic control costs. With profile data from FHWA Long-Term Pavement Performance (LTPP) General Pavement Study 3 (GPS-3) test sites, examples are provided to show how the apparent slab rocking and pumping volumes develop over time for most GPS-3 test sections that have shown significant faulting. The calculated pumping volume rate per equivalent single-axle load (ESAL) is shown to be relatively constant over time at these LTPP test sites. A preliminary linear regression predictive model for pumping rate per ESAL as a function of pavement design parameters is provided based on the test group of faulting GPS-3 pavements. This study indicates that pumping rate can be reduced with thicker and longer slabs and thicker layers of erosion-resistant base and subbase overlying erosion-susceptible subgrades. Slab lengths less than 15 ft (4.57 m) long appear noticeably more susceptible to rocking and pumping. Sites with high pumping rates typically have a combination of unusually large slabs locked in upward curvature and erosion-susceptible cross-section designs.

Pollution Intrusion on Soil-Pavement System

The performance of both flexible and rigid pavement is a function of the constituent materials and their susceptibility to physical and chemical stress and degradation. To that end, specific phenomena that accompany and characterize the interaction of the soil-pavement system with the environment are discussed. Mechanisms of pollution intrusion through the pavement wearing surface, base, subbase, and subgrade soil layer are evaluated. Liquid movement phenomena and processes in the soil mass such as infiltration, percolation, and hydraulic conduction related to the soil-pavement system are examined. Laboratory data that reflect the effects of pollution intrusion on the behavior, stability, and performance of soil-pavement systems are presented and remedial actions on these effects are discussed. Pollution intrusion is manifested by changes in system variables, including solution pH, dielectric constant, ionic composition, temperature, and moisture content. These changes are shown to influence pavement design parameters, such as soil physical properties, compressibility, and stress.