Distress In Flexible Pavements Research Articles

Asphalt Pavement Damage Detection through Deep Learning Technique and Cost-Effective Equipment: A Case Study in Urban Roads Crossed by Tramway Lines

Asphalt pavements are subject to regular inspection and maintenance activities over time. Many techniques have been suggested to evaluate pavement surface conditions, but most of these are either labour-intensive tasks or require costly instruments. This article describes a robust intelligent pavement distress inspection system that uses cost-effective equipment and the ‘you only look once’ detection algorithm (YOLOv3). A dataset for flexible pavement distress detection with around 13,135 images and 30,989 bounding boxes of damage was used during the neural network training, calibration, and validation phases. During the testing phase, the model achieved a mean average precision of up to 80%, depending on the type of pavement distress. The performance metrics (loss, precision, recall, and RMSE) that were applied to estimate the object detection accuracy demonstrate that the technique can distinguish between different types of asphalt pavement damage with remarkable accuracy and precision. Moreover, the confusion matrix obtained in the validation process shows a distress classification sensitivity of up to 98.7%. The suggested technique was successfully implemented in an inspection car. Measurements conducted on urban roads crossed by tramway lines in the city of Palermo proved the real-time ability and great efficacy of the detection system, with potentially remarkable advances in asphalt pavement examination efficacy due to the high rates of correct distress detection.

Investigation of Rutting Performance in Geogrid-Reinforced Asphalt by Penetration Test.

Permanent deformation, or rutting, is one of several critical distresses in flexible pavements. This paper introduced a novel experimental method, a penetration test, for asphalt mixtures to quantify the effects of glass fibre geogrids embedded in asphalt under repeated loading. It was found that the evolution of permanent deformation (εp) and its strain rate have three clearly identifiable stages. It was also observed that the presence of the geogrid increased the flow number and the number of cycles to failure significantly compared to control samples. Some of the current εp fitting models were found to be valid for deformation prediction under penetration. In addition, a new simple FN calculation method was also proposed based on strain rate and it showed consistent results. In particular, geogrid type "Grid10", which has smaller aperture size (12.7 mm) had slightly better reinforcement performance regarding the rutting resistance due to its larger contact area. Overall, the test and data analysis method presented in this study could be an important reference for future investigations on geosynthetic-reinforced pavement materials.

A Simplified Protocol for Permanent Deformation Characterization of Asphalt Concrete

Abstract Permanent deformation (PD; or rutting) is one of the major distresses in flexible pavements. To predict PD in asphalt concrete, repeated and recovery load tests are usually conducted in the laboratory. The full-blown repeated load permanent deformation (RLPD) is time-consuming, limiting its use in research programs and developing correlations. Therefore, a quicker yet reliable procedure is needed for use in performance prediction programs. This paper presents a simplified and quicker procedure to obtain PD model parameters. It is illustrated using laboratory tests on field specimens. The procedure uses one specimen, compared with three specimens in the full-blown RLPD test, to be tested at two temperatures, the highest and lowest in the RLPD test, under the same conditions as in the RLPD test. The results of any intermediate temperature are obtained from the calibrated model. Two approaches are presented for analyzing the test results: the power equation in the AASHTOWare program, and the construction of a master curve. In the full-blown testing program with three specimens and three temperatures, the master curve approach fitted the results better than the power law. In the simplified procedure, the fitting of the two approaches is almost identical. Results obtained from tests conducted on six mixes show (1) testing one specimen at the highest temperature only and extrapolating the results overpredicts the material behavior at intermediate and low temperatures, and (2) the master curve from the simplified procedure compares very well with the one from the full-blown RLPD program.

Performance Assessment of Self-Healing Polymer-Modified Bitumens by Evaluating the Suitability of Current Failure Definition, Failure Criterion, and Fatigue-Restoration Criteria

Fatigue cracking is a common form of flexible pavement distress, which generally starts and spreads through bitumen. To address this issue, self-healing elastomer (SHE) modified bitumens were elaborated to assess whether these novel materials can overcome the neat asphalt (NA) fatigue performance and whether the current failure definition, failure criterion, and fatigue-restoration criteria can fit their performance. All bitumens were subjected to short-term and long-term aging. Linear amplitude sweep (LAS) test, LAS with rest period (LASH), and simplified viscoelastic-continuum-damage (S-VECD) model were utilized to appraise the behavior of the mentioned bitumens. The results showed that maximum stored pseudo-strain energy (PSE) and tau (τ) × N (number of loading cycles) failure definitions exhibited high efficiency to accommodate the fatigue life of NA and SHE-modified bitumens. Both failure criteria identified that SHE-modified bitumen (containing 1% of SHE) showed the highest increment of fatigue performance (67.1%) concerning NA. The failure criterion based on total released PSE, in terms of the area under the released PSE curve, was the only failure concept with high efficiency (R2 up to 0.999) to predict asphalt binder fatigue life. As well, the current framework to evaluate bitumen self-restoration failed to fully accommodate asphalt binder behavior, because bitumen with higher restoration could not exhibit greater fatigue performance. Consequently, a new procedure to assess this property including fatigue behavior was proposed, showing consistent results, and confirming that SHE-modified bitumen (containing 1% of SHE) exhibited the highest increment of fatigue performance (154.02%) after application of the rest period. Hence, the optimum SHE content in NA was 1%. Furthermore, it was found that a greater number of loading cycles to failure (Nf) did not ensure better fatigue performance and stored PSE influenced the bitumen fatigue behavior.

Investigation of Permanent Deformation in Iraqi Highways- Iraqi Expressway No.1 as a Case Study

Pavement rutting as a permanent deformation is a major type of distress in flexible pavements. In Iraq, the rutting in Expressway pavements represents a severe problem due to its widespread, and high severity and distress density levels. Therefore, driving is profoundly dangerous and causes severe damage to the vehicle’s parts and the life of its riders. To date, the number of comprehensive research on pavement rutting has been limited in Iraq, owing to several technical, logistic, and economic considerations. The current research studies the major mechanisms responsible for rutting and evaluates the structure of the Iraqi Expressway No.1 at selected sections. The work encompasses field and laboratory aspects. The field work involved; performing field surveys to investigate the pavement rutting condition and its extension with depth, characterizing pavement layers in terms of geometric material properties, and collecting field samples for lab tests. The laboratory work was detailed and included; performing a set of standard lab tests on samples taken from the asphalt, the subbase, and the subgrade layers as well as the natural ground. In addition, the project’s archive was searched for specific design information and limitations. In order to assess pavement rutting in the selected sections of Expressway No.1/R9 (A and B), two well-established evaluators were considered; The rutting severity levels and the distress density.

Development of a flexible pavement condition index for urban road network

In the urban pavement management, it is essential to develop urban pavement condition indexes to support Municipal Secretariat for Infrastructure on decisions making in relation to maintenance and rehabilitation (M&R). The aim was to develop an urban pavement condition index (UPCI) for flexible pavements and perform a comparative analysis with some pavement condition indexes (PCI). The work method followed such steps: definition of sampling size; formation of rating panel and training; data collection about present serviceability rating (PSR) and flexible pavement distress; development of an UPCI; and, comparative analysis with some PCI. Multilinear regression modeling based on distresses and PSR carried out the UPCI, in accordance with some statistical assumptions such as homoscedasticity, serial correlation, multicollinearity and normality tests. The PCI chosen carried out variability between them and the PSR, which was statistically analyzed by errors and correlation tests. Lastly, the proposition of an urban pavement condition index for flexible pavement allows a better M&R planning, budget distribution and benefits to the population, because well-kept pavements promote comfort, travel time reduction and safety to the users.

Factors Contributing to Fatigue Cracking in Flexible Pavements in Oklahoma: A Case Study Using Laboratory and Field Investigation and AASHTOWare Simulation

Fatigue cracking is one of the major structural distresses in flexible pavements. In this study, probable causes of fatigue cracking were investigated using field and laboratory testing and In this study, probable causes of fatigue cracking were investigated using field ang laboratory testing and AASHTOWare Pavement ME Design (PMED) simulations. Field tests including Ground Penetrating Radar (GPR), Falling Weight Deflectometer (FWD), and Dynamic Cone Penetration (DCP) were performed on a flexible pavement section of US 412 located in Noble County, Oklahoma. Also, asphalt cores and soil samples were collected for laboratory testing. The GPR test results revealed significant delamination in the asphalt layer. Also, the GPR images indicated that the disturbance zone was confined within the asphalt layer and cracks were generated from surface as well as from existing pavement layers below. The DCP and FWD test results indicated that the pavement section was not structurally adequate to support traffic and needed rehabilitation in the near future. The moduli of the asphalt layers were found to be quite low, indicating improper compaction during construction. Also, the densities of the top-lifts of the asphalt cores were found to be low. Moreover, the cracking resistance of the extracted asphalt cores was poor based on the Illinois flexibility index test results. Superpave Performance Grade of the extracted binder indicated excessive aging of the binder because of long exposure to the environment. The brittleness of mix resulting from aging was considered a potential contributor to fatigue cracking of the pavement at this site. A parametric study was conducted to understand the variation of fatigue cracking with the changes in input properties in PMED, namely pavement structural components and material properties. Pavement thickness, roadway densities, and layer moduli of existing underlying pavement were found as the most influential factors. The findings of the parametric study supported the findings of the field and laboratory investigation.

Stress–strain dependent rutting prediction models for multi-layer structures of asphalt mixtures

ABSTRACT Since rutting is a major distress in flexible pavements at intermediate and high temperatures, rutting models with concise expressions and satisfying accuracy can have considerable contributions to the pavement design, maintenance and rehabilitation. In this circumstance, two mechanistic-empirical rutting models were proposed in this study. The models were adapted from traditional rutting models and involve advanced mechanical aspects such as strains and stress invariants under moving loads and a yield criterion for asphalt mixtures. This paper includes detailed explanations of model expressions, qualitative comparisons with current models and model applications in an innovative laboratory test. The laboratory test and finite element simulation of asphalt mixtures under moving loads were used to calibrate, validate and check the sensitivity of the proposed models. The results showed the proposed models successfully captured rutting development in asphalt mixtures; they also reasonably predicted rutting behaviors of layered structures under different loading and environmental conditions. In model applications, effects of different factors on material properties, structural strain and stress responses and rutting development were evaluated. Finally, the determination of model parameters in the proposed models was discussed and recommended for further research.

Evaluation of the Effect of UHMWPE on the Low-Temperature Cracking of Hot-Mix Asphalt

AbstractLow-temperature cracking is a very common type of distress in flexible pavements in cold areas that extends in the form of longitudinal and transverse cracks on the surface layer. Modifying...

The influence of cohesion and adhesion parameters on the moisture sensitivity of modified Asphalt mixtures with polymer additive

ABSTRACT Moisture sensitivity is one of the common distresses in flexible pavements due to the deteriorating effect of water on adhesion of bitumen-aggregate and cohesion of mastic. In the present study, the effect of the styrene–ethylene–butylene–styrene as bitumen modifier was examined on the moisture damage potential of control and modified asphalt mixtures using thermodynamic and mechanical methods. The results of this study indicated that the modified asphalt mixtures have significantly better resistance than the control samples. In addition, the results of the thermodynamic parameters showed that changes in the surface-free energy components of the modified bitumen have improved the adhesion of these bitumens to high silica aggregates that are susceptible to moisture. Moreover, the use of styrene–ethylene–butylene–styrene increases the surface-free energy of mastic film, which also increases the resistance to cohesion failure. Furthermore, the results of the amount of energy released during the stripping event show that the use of bitumen modifying polymer additive has reduced the amount of de-bonding energy. This indicates that the tendency for bitumen to detach from the aggregate surface in the presence of water has decreased from the thermodynamics view.

Asphalt pavement design optimisation: a case study using viscoelastic continuum damage theory

ABSTRACT Fatigue cracking is the main type of distress in flexible pavements in Brazil. Numerical models that are based on viscoelastic continuum damage (VECD) theory can help to explain the damage evolution process in asphalt mixtures, thereby allowing the proper analysis of the fatigue phenomenon. This paper aims to characterise and verify the fatigue behaviour of four test sites constructed with dense asphalt mixtures in Santa Maria, Brazil, employing field monitoring, linear viscoelastic characterisation, uniaxial cyclic fatigue testing, the simplified VECD (S-VECD) model, and FlexPAVETM software. This study’s results are coupled with a cost/benefit analysis of the evaluated test sites. The constructed sites are compared to simulated optimal pavement designed using FlexPAVETM and fatigue damage transfer function. The results indicate that this study’s methodology can predict fatigue damage evolution by identifying early cracking in two of the test sites and capturing good fatigue resistance in the other two sites. Furthermore, in both cases of early cracking, the design requirements for fatigue resistance could be met by increasing the asphalt layer thickness (optimal pavements), which significantly reduced the US$/NFATIGUE ratio. Thus, an improved cost/benefit ratio was realised for the pavements designed using this methodology and analysed using only an established fatigue criterion.

Effect of Aggregate Gradation on Rutting of Thin Asphalt Overlay

Permanent deformation (rutting) of asphalt pavements has a major impact on the service life of pavements. Rutting reduces the performance of the pavement and produces serious hazards for highway users. Due to the axle loads incensement, and high local summer temperature, rutting became the major distress in flexible pavements for many countries. Recently, thin asphalt overlay (TAO) is recommended as a significant remedy technique for deteriorated pavements. Aggregates are one of the main structure materials asphalt paving mixtures, whereas, aggregate properties remarkably effected on the asphalt pavements performance. Aggregate gradation is representing the significant feature of aggregates that affecting permanent deformation of traditional hot mix asphalt (HMA) thick pavement layers. The aim of this study is to examine the influence of aggregate gradation differences on rutting features of modified TAO mixtures that comprising waste polymers. The evaluation process included the preparation of polymer modified asphalt (PMA) comprising two types of additives, namely, Crumb Rubber Modifier (CRM) and Low-Density Polyethylene (LDPE). CRM and LDPE in the form of fines that have a particle size under 250 um were used as additives to liquid neat asphalt, individually and collectively by weight of virgin asphalt; i.e., PMA included 15.0% of CRM and (2.5. %, 5.0%, 7.5% and 10.0% of LDPE. Three types of aggregate gradations were used, i.e. 12.5, 9.5 and 4.75mm, Nominal maximum aggregate size, (NMAS). The Superpave mix design system was adopted in volumetric proportioning of prepared mixtures, while Wheel Tracking (WT) test was used to determine the rut depth characteristics for prepared mixtures. about 30 asphalt concrete specimens were prepared to forecast the TAO behavior concerning permanent deformation for wearing course type III A and B according to State Corporation of Roads and Bridges in Iraq, while for 4.75mm, NMAS (sand asphalt layer) an abroad specification was used. Results demonstrated that the aggregate gradation plays a vital role in increasing permanent deformation for several type of TAO mixtures. Also, the addition of CRM by 15% to the neat asphalt led to an increase in the resistance of the mixture to permanent deformation. Moreover, PMA with LDPE became hardener (higher viscosity) which led to increase binder stiffness, whereas a consequent is stiffening the mixture. Therefore, optimizing aggregate gradation with PMA including waste polymers can limited the rutting occurrence distinguishably

Fundamental Approaches to Predict Moisture Damage in Asphalt Mixtures: State-of-the-Art Review

Moisture susceptibility is still one of the primary causes of distress in flexible pavements, reducing the pavements’ durability. A very large number of tests are available to evaluate the susceptibility of a binder aggregate combination. Tests can be conducted on the asphalt mixture, either in a loose or compacted form, or on the individual components of an asphalt pavement. Apart from various mechanisms and models, fundamental concepts have been proposed to calculate the thermodynamic tendency of a binder aggregate combination to adhere and/or debond under wet conditions. The aim of this review is to summarize literature findings and conclusions, regarding these concepts as carried out in the CEDR project FunDBits. The applied test methods, the obtained results, and the validation or predictability of these fundamental approaches are discussed.

The Relation between Structural Distresses in the Flexible Pavements

The pavement management system deals with maintenance, repair, and rehabilitation of pavements. Pavement Condition evaluation is one of the critical steps in the pavement management system. It required distresses identification and measurement on the pavement surface. Structural distresses are an essential component in the pavement condition evaluation. To take decisions precisely, it is necessary to develop the relationship between various distresses. In this study, the relationship between structural distresses in flexible pavements has been analyzed. The primary structural distresses as longitudinal cracking, transverse cracking, Fatigue cracking, Block cracking, and deflection has been considered for the study. The correlation between all the distresses has been analysis. For correlation analysis, the Pearson Correlation Coefficient is used. The values of the Pearson correlation coefficient indicate that there is a strong positive relationship betweenthe distresses. Furthermore, to develop a prediction model, the regression analysis has been done. The values of the coefficient of regression indicate that the relationship is linear and positive between the structural distresses.

Modeling pavement damage and predicting fatigue cracking of flexible pavements based on a combination of deterministic method with stochastic approach using Miner’s hypothesis

Distress in flexible pavements has been a problem in many countries due to the increase in road traffic and vehicle loads. One of the most important distress modes in the design of pavements is fatigue cracking. Despite the fact that there have been considerable efforts in recent years in fatigue performance evaluation and the design process of flexible pavements, there is still a need for further studies to overcome the difficulty in predicting fatigue cracking in terms of damage distribution considering the uncertainty associated with the input parameters of pavement life and traffic repetitions. The purpose of this paper is to develop a methodology for modeling pavement damage and predicting fatigue cracking of flexible pavements based on a combination of deterministic method with stochastic approach using Palmgren–Miner’s hypothesis. Four predictive models are introduced and used in a comprehensive case study to estimate the fatigue life of the pavement surface layer. The solutions are obtained through numerical integration based on Gaussian quadrature method. The results reveal that pavement damage has a broad range of distribution in which the actual traffic load repetitions has a Poisson distribution, while the traffic repetitions to failure follows a lognormal distribution.

A model to predict creep compliance of asphalt mixtures containing recycled materials

Thermal cracking is one of the major distresses in flexible pavements, especially in the northern part of the U.S. and Canada. With the increasing use of recycled materials like reclaimed asphalt pavement (RAP) and recycled asphalt shingle (RAS), asphalt pavements have become more susceptible to thermal distresses. Therefore, such asphalt concrete (AC) mixtures should be carefully investigated to ensure that performance is not compromised in the pursuit of an economical solution. The Pavement ME Design uses the empirically developed model for the prediction of creep compliance as an input for Level 3 analysis, which uses the mix and binder properties. However, this prediction model cannot be applied for every climatic and mix design conditions; therefore, different researchers came up with modified models for different states within the U.S. The impact of recycled materials was not captured in the MEPDG as well as in the modified models. This research proposes a new model that captures the effect of recycled materials. It was observed that softer binder and higher asphalt content results in more compliant, while recycled materials tend to decrease the compliance. Hence, softer binder and recycled materials tend to counterbalance each other’s impact. From model analysis, it was found that the existing MEPDG model significantly overestimates creep compliance compared with actual measured values. The proposed model can capture the effect of asphalt binder replacement (ABR) and has been validated with randomly selected data and found to exhibit good correlation with lab testing data.

Selecting the Affected Factors on Pavement Distress Problems Using Analytical Hierarchy Process [AHP

This study describes the implementation of analytical hierarchy process [AHP] in pavement multi-criteria selection problem solving. The practice of expressing flexible pavement distress priority is widely accepted. However, an insistent demand exists for a technique that allows decision makers to determine their priorities, rational weights of the importance of pavement distress priority and the ranking of these factors. In this study, AHP is adopted in selecting the best level of distress in flexible pavements in Malaysia as an example of a tropical region. Knowledgeable and experienced experts in flexible pavement maintenance at jabatan kerja raya [JKR] and Kumpulan Ikram Sdn Bhd [IKRAM] were interviewed; as pairwise comparisons, their inputs were structured. Four criteria are set as follows: cracking, surface defects, surface deformations and patching and potholes. These criteria developed into a few other sub-criteria. Results show that cracking is the most significant factor [0.5500], followed by surface deformations [0.2300], patching and potholes [0.1600] and surface defects [0.0600]. Thus, cracking has the most significant distress among the four factors.

Fatigue performance predication model based on dissipated energy criteria using DSR under controlled-strain mode

Fatigue cracking is one of the primary modes of distress in flexible pavements that has an important economic impact. This paper describes the use of a dynamic shear rheometer (DSR) for fatigue performance testing of hot asphalt mixture under controlled-strain mode. 150 mm-diameter and 50 mm-height HMA finger samples used for the fatigue sequence procedure were developed and adopted to prepare the DSR samples. This paper reports the evaluation of fatigue resistance of asphalt mixture finger sample cores that were recovered from the field sections from Samawah–Nasiriyah City atrial road (97 km in the middle region of Iraq) using different continuum damage mechanics approach. The analysis has focused on comparing the dissipated pseudo strain energy (DPSE), energy ratio (ER) and energy stiffness ratio (ESR) in addition to the traditional approach under the controlled-strain mode. The results are used to develop guidelines for the design of fatigue-resistant mixtures in Iraq and to relate the mixture design to the structural design to optimize performance.

Application of mechanistic empirical approach to predict rutting of superpave mixtures in Iraq

In Iraq rutting is considered as a real distress in flexible pavements as a result of high summer temperature, and increased axle loads. This distress majorly affects asphalt pavement performance, lessens the pavement useful service life and makes serious hazards for highway users. Performance of HMA mixtures against rutting using Mechanistic- Empirical approach is predicted by considering Wheel-Tracking test and employing the Superpave mix design requirements. Roller Wheel Compactor has been locally manufactured to prepare slab specimens. In view of study laboratory outcomes that are judged to be simulative of field loading conditions, models are developed for predicting permanent strain of compacted samples of local asphalt concrete mixtures after considering the stress level, properties of local material and environmental impacts variables. All in all, laboratory results were produced utilizing statistical analysis with the aid of SPSS software. Permanent strain models for asphalt concrete mixtures were developed as a function of: number of passes, temperature, asphalt content, viscosity, air voids and additive content. Mechanistic Empirical design approach through the MnPAVE software was applied to characterize rutting in HMA and to predict allowable number of loading repetitions of mixtures as a function of expected traffic loads, material properties, and environmental temperature.

Evaluating the effect of amorphous carbon powder on moisture susceptibility and mechanical resistance of asphalt mixtures

The detrimental effect of water in asphalt mixtures is regarded as one of the major distresses in flexible pavements since it is generally accompanied by mechanical related distresses. This detrimental effect is a complex phenomenon and involves thermodynamic, chemical, physical and mechanical processes. Several methods are used to reduce the moisture sensitivity of mixtures, one of which is to add hydrophobic material in asphalt mixtures as an additive. In this study, amorphous carbon powder, a by-product of paraffin production factory, is used as a replacement of filler (25, 50, 75, and 100%) and as a modifier of bitumen (5, 10, and 15%) to improve the hydrophobicity of mixtures. The sessile drop test was used along with several conventional methods to investigate the hydrophobicity and moisture sensitivity of mixtures. Mechanical stability of mixtures modified by the amorphous carbon powder was also studied using dynamic creep and wheel tracking tests. The results showed that not only did the hydrophobic powder improve the moisture sensitivity, but it also increased the rutting resistance of mixtures. The enhancement of moisture susceptibility was more pronounced when carbon powder was incorporated as filler compared to that of using as binder modifier. However, dynamic creep and wheel tracking test results showed bitumen modified mixtures are more resistant to mechanical deformation. The results of this research provide more insight on the application of waste carbon powder to produce environmental friendly asphalt mixture.