Flexible Pavement Performance Research Articles

Evaluation of flexible pavement performance based on HDM-4 and international roughness index

The HDM-4 aids in estimating the deterioration of the pavement as well as the intricate interactions between the environment, vehicles, the surface, and the structure of the pavement. It predicts how the roads will deteriorate over time due to the increased traffic. The current study was carried out at Hyderabad, particularly roads which are subjected to the heavy traffic. The study was adopted for Dhulapally to Bahadurpally (DB), Gandimaisamma to Bowrampet (GB), Gandimaisamma to Medchal (GM), and Kompally to Dhulapally (KD). Among these roads commonly observed distress was collected like patches, alligator cracking, pothole, rutting, and edge drop etc. This papers describes the current and future performance of the roads (10 years), the progress of the distress were predicted using the HDM-4. The study addresses the major causes of distress and their reasons of given section. The study concluded the prediction of pavement life for 10 years in terms of IRI values of the different sections. The study revealed the failure of roads section due to distress for the period of 10 years with and without maintenance, it also helps in decision making for apply further maintenance treatment of this particular routes.

Influences of bus traffic loading on asphalt concrete rutting

ABSTRACT Permanent deformation is the primary failure mode for the asphalt concrete (AC) pavement in urban environment. It is mainly caused by a combination of heavy traffic load, low vehicle speed and channelised traffic. A rut prediction model would therefore be a valuable tool for planning maintenance scheduling and selecting an appropriate asphalt material. This study uses the PEDRO (Permanent deformation in asphalt concrete layers for roads) model to evaluate the rutting performance of flexible pavements in dedicated bus lanes and intersections in urban areas. For this purpose, three road sections along a bus lane in Malmö, Sweden, were selected. To achieve this, AC cores from the road sections were tested using a Shear Box Tester to characterise the asphalt mixtures. Traffic data such as axle load, tyre configuration, speed, and lateral wander distribution of vehicles, and climate data were measured for the selected sections. Field measurements were carried out to assess the structural conditions of the pavements and to measure transverse profiles. This study introduced a procedure for the evaluation and local calibration of the PEDRO rutting model. The results revealed that the prediction of the transverse profiles are generally in good agreement with the rut measurements.

Structural health assessment of pavement sections in the southern central United States using FWD parameters

Various Departments of Transportation in the South-Central States and elsewhere have made extensive use of the Non-Destructive Testing (NDT) surface deflection bowl data. The falling weight deflectometer (FWD) test is a popular NDT-based test used by transportation authorities to evaluate the performance of flexible pavement. Nevertheless, it is rare to develop a method for evaluating pavement sections using FWD data from all sensors. There is a constant demand for DOTs and highway agencies to have a streamlined approach that can be applied directly to their databases. This research focuses on extending and verifying the concept of previously published area ratio parameters to the pavement section of South-Central States (Arkansas, Louisiana, New Mexico, Oklahoma, and Texas) in order to properly analyze pavement performance. Simulation-based deflections are employed to strengthen deflection-based parameters and minimize the need for lengthy FWD field testing. Ninety-seven pavement sections in these states are being investigated for the implementation and validation of simplified processes that will be widely accessible to different transportation authorities in order to assess pavement problems at the network level.

The influence of truck speed on pavement defects

ABSTRACT The response of asphalt material depends on the rate of loading and varies from elastic to plastic. Therefore, the behaviour of flexible pavement would also be different along the entire length of a road because of truck speed changes due to the existence of police checkpoints, bus stations, speed bumps, intersections, horizontal and vertical curves, and climbing lanes. The objective of this study is to investigate the effect of truck speed on the performance of flexible pavement. Thus, analyses were conducted for various truck speeds (1–75 km/hr) on three different pavement structures and three traffic levels using AASHTOWare Pavement ME Design 2.5.5 for the local conditions of Izmir, Turkey. The analysis results of the study manifested that a reduction in traffic speed (75–1 km/hr) on a road resulted in higher pavement distress. According to the results, reducing truck speed from 25 to 1 km/hr resulted in a rapid increase in AC rutting, alligator cracking and top-down cracking by 13.3 mm, 10.6% and 1473.8 m/km, respectively. It is expected that the outcomes of this study would promote the local calibration of the mechanistic-empirical pavement design guide (MEPDG) and pavement design in Turkey and the region.

Survival Analysis for Asphalt Pavement Performance and Assessment of Various Factors Affecting Fatigue Cracking Based on LTPP Data

Pavement performance is the ability of pavement to remain in an acceptable condition to serve the intended users over a period of time. There are several principal, combined factors that affect flexible pavement performance such as environmental conditions, pavement materials, and traffic loads. Vehicle overloading is considered one of the most significant causes of accelerating flexible pavement deterioration, reducing the pavement’s design life, and affecting the overall sustainability of the pavement system. Therefore, researchers are continuously examining pavement systems with a view to finding the most suitable solutions for sustainable development in road construction systems in order to reduce both costs and pollution. In this study, we present a framework to conduct nonparametric and parametric survival analysis for asphalt pavement test sections, to assess the influence of using reclaimed asphalt pavement (RAP) on fatigue service life, to indicate the most significant subset of risk factors (covariates), and to study the effect of overweight axles on flexible pavement performance. All the data concerned were extracted from the long-term pavement performance (LTPP) program. The Kaplan–Meier (KM) survival probability curves of multiple pavement distresses were developed to compare the failure probability for various distresses and to determine the median survival time for each distress. The fatigue survival curves for the test sections using RAP and virgin materials were developed separately and the equality of the two survival curves was tested and affirmed. Several parametric survival analyses were conducted to select the most significant subset of covariates. For fatigue cracking and, after dropping the insignificant predictors, a model was developed to show the quantitative relationship between fatigue failure time and potentially influential factors. The analysis indicated that the increase in the percentage of overloaded axles from 0% to 20% can reduce the fatigue survival life of flexible pavement by up to 55%. In the absence of overweight axles, a one-inch increase in asphalt layer thickness can extend the fatigue service life by about half a year. However, in the presence of 20% of overweight axles, a one-inch increase in thickness can extend the fatigue service life by only 0.22 years. Therefore, additional virgin materials and resources are needed to maintain traffic conditions in the road network and to compensate for the reduction in fatigue service life. Moreover, the effect of the increase in overweight axles from 0% to 15% on reducing the fatigue survival life is found to be similar to the effect of increasing the AADTT tenfold. Therefore, the sustainability of pavement is directly affected by the fatigue survival life.

Investigating long-term performance of flexible pavement using Bayesian multilevel models

Many factors affect the performance of rehabilitative treatments for asphalt concrete pavements. However, which factors have been causing the deterioration of their long-term performance is still unclear. We considered the nested and panelled structure of pavement performance data and the unobserved heterogeneity among sites using multilevel Bayesian regression models. We incorporated alligator cracking, rutting and roughness represented by the international roughness index (IRI) as performance indicators. To verify the existence of unobserved heterogeneity, we adopted an iterative modelling path by adding the per-state or per-climatic region random parameters into the models. We then based our inference of the significant factors on the chosen models that are predictive and causally sound. The results show that there existed considerable heterogeneity among different sites and climatic regions. Including per-state or per-region intercepts improved the models’ predictive capacity and accounted for the unobserved heterogeneity.

Comprehensive Study on the Performance of Waste HDPE and LDPE Modified Asphalt Binders for Construction of Asphalt Pavements Application.

This research is aimed at investigating the mechanical behavior of the bitumen by the addition of high-density polyethylene (HDPE) and low-density polyethylene (LDPE) obtained from waste plastic bottles and bags. Polymers (HDPE and LDPE) with percentages of 0%, 2%, 4%, and 6% in shredded form by weight of bitumen were used to evaluate the spectroscopic, structural, morphological, and rheological properties of polymer-modified binders. The rheological properties for different factors; viscosity (ἠ) from Rotational Viscometer (RV), rutting factor G*/Sin (δ), fatigue characteristics G*. Sin (δ), for the modified binder from dynamic shear rheometer (DSR), Short and long-term aging from rolling thin film oven (RTFO), and pressure aging vessel (PAV) was determined. The thermal characteristics, grain size, and texture of polymers for both LDPE and HDPE were found using bending beam rheometer (BBR) and X-ray diffraction (XRD), respectively. Fourier transform infrared (FTIR) analysis revealed the presence of polymer contents in the modified binder. Scanning electron microscopy (SEM) images revealed the presence of HDPE and LDPE particles on the surface of the binder. Creep Rate (m) and Stiffness (S) analysis in relationship with temperature showed a deduction in stress rate relaxation. Results have revealed the best rutting resistance for 6% HDPE. It also showed an improvement of 95.27% in G*/Sin (δ) which increased the performance of the bituminous mix. Similarly, the addition of 4% LDPE resulted in maximum dynamic viscosity irrespective of the temperatures. Moreover, fatigue resistance has shown a significant change with the HDPE and LDPE. The festinating features of waste plastic modified binder make it important to be used in the new construction of roads to address the high viscosity and mixing problems produced by plastic waste and to improve the performance of flexible pavements all over the world.

Development of Prediction Models for Performance of Flexible Pavements in Kansas with Emphasis on the Effects of Subgrade and Unbound Layers

This study resulted from the need for better consideration of subgrade and unbound layers on the performance of flexible pavements in Kansas. Thus, the main objective was to develop pavement performance prediction models with emphasis on the effects of subgrade and unbound layers. To this end, pavement distress data, which were collected over several years across the state of Kansas, including rutting, fatigue cracking, transverse cracking, roughness and core analysis, served as the input data into statistical models. The effects of subgrade and unbound layers were represented by the corresponding results of dynamic cone penetrometer (DCP) tests and thickness of the unbound layer. In addition, traffic volume was represented by average annual daily truck traffic (AADTT). Multiple statistical analyses identified positive correlations of dynamic cone penetration index (DPI) and rate of total rutting, and DPI and percent of good core. Negative correlation was discovered between DPI and fatigue cracking code one, and DPI and percent of poor core. AADTT was positively correlated with transverse cracking codes one and two while it had no correlation with transverse cracking code zero. Thickness of the unbound layer was negatively correlated with pavement roughness and percent of poor core, while it was positively correlated with the percent of good core. Finally, the recommendation for minimum acceptable value of California bearing ratio (CBR) was provided based on the correlation between DPI and rate of change of rutting code. The recommendation enables the selection of a CBR value based on the number of years required for unit increase in the rutting code.

Long-Term Performance of Flexible Pavements Constructed on Recycled Base Layers

There has been an increased interest in using reclaimed asphalt pavement (RAP) aggregates as a base course in Wisconsin for the offered economic and environmental benefits. Laboratory studies showed that RAP can have resilient modulus values higher than typical natural aggregates, and can also have higher durability, especially in freeze–thaw cycles. However, it is also recognized that RAP exhibits temperature sensitivity and larger permanent deformations than natural aggregates. How these characteristics manifest themselves in the northern U.S. climates can only be assessed by long-term observation of field performance. Wisconsin Department of Transportation (WisDOT) has been using RAP as a base course for over 30 years. The qualitative assessment of WisDOT roads constructed with RAP showed they are performing adequately. However, this impression has not yet been verified quantitatively. This paper presents a quantitative assessment and comparisons for field performance of pavement test sections constructed with RAP and natural crushed aggregate (CA) base course layers in Wisconsin. The performance was evaluated using pavement distress surveys of roadways containing RAP and CA, falling weight deflectometer (FWD), dynamic cone penetrometer (DCP) tests, and analysis of WisDOT’s available data. Based on the field evaluation, the performance of the hot mix asphalt (HMA) pavements with RAP was found adequate and comparable to those with CA base course layers. A recommendation was given that WisDOT shall continue the practice of using RAP in base course layers of HMA pavements, given proper quality checks for materials, and proper quality control/quality assurance measures being applied during construction.

Analysis of the effect of unbound granular base characteristics on the performance of flexible pavements

The influence of aggregate properties on the mechanical behaviour of granular materials is widely recognized in the literature, but default values are considered most of the time for pavement design. This limits their consideration to accepting materials that show values in defined ranges of indicative properties. It is expected that materials with similar particle size distributions but different characteristics will perform differently. This work evaluated the influence of considering the characteristics of the aggregate base and its effect on stiffness and damage. Two approaches were used to modify the adjustment coefficients in stress-dependent resilient modulus models to consider the characteristics of the granular materials. The results showed that thin pavements were particularly sensitive to these characteristics, with pavement capacity expected to be higher than in default models when considering crushed aggregates. In contrast, the capacity may be as low as 40% of the conventional estimate for partially crushed aggregates.

Performance of Asphalt Mixture Incorporated Encapsulated Cigarette Butts as Bitumen Modifier

Cigarette butts are non-biodegradable waste, and the difficulties in dealing with cigarette waste is a big concern for communities and environmental groups all over the world. In past years, cigarette butts has been increasingly used on flexible pavement and has become one of the causes that increases pavement strength and reduces environmental challenges. Environmental factors are external influences that affect the performance of flexible pavements. These include snow, chemicals, water, and ageing issues. The aim of this research is to evaluate the mechanical and physical properties of asphalt mixture incorporating encapsulated cigarette butts. Asphalt concrete has a number of problems, including rutting, moisture removal, and binder drain. The use of asphalt is restricted due to high temperatures that cause rutting cracking of the asphalt or coating layer. Therefore, it is necessary to modify asphalt and improve its quality with less affects to environment. In this research, experiments were carried out to compare two types of asphalt which are unmodified asphalt and modified asphalt mixture. For modified asphalt, various percentages of encapsulated cigarette butts were added to the mixtures. The additive used was encapsulated cigarette butts with increment 0%, 0.2%, 1% and 3% for the bitumen and 0%, 5%, 10% and 15% for asphalt mixture. Penetration test, softening point, ductility test, penetration index, los angeles (LA) abrasion test, marshall tests, indirect tensile strength test and dynamic creep test were performed. The findings of the studies performed in this project reveal that varying the percentages of cigarette butts in the asphalt concrete mixture obviously differs in the mechanical and physical characteristics of asphalt mixture. As a result, the addition of CBs to AC resulted in a different abrasion loss value when compared to unmodified AC. At 10% CBs put into the asphalt mixture, the abrasion loss was chosen as the most advantageous level for increasing the performance of AC mixture. Based on the results of the mechanical and physical tests we can infer that 5% of CBs is the best percentage of cigarette butts to add in asphalt mixture. So this study proved that cigarette butts to be an effective material is used as an addition to asphalt binder because it improves performance by increasing paving strength and stiffness.

Simulating the Impact of Vehicle Speed on the Life of Bituminous Pavement

Due to the visco-elastic nature, the performance of flexible pavements depends on temperature and loading conditions. This study investigates the influence of different speeds of vehicle and binder type on stiffness modulus and the corresponding pavement life. The filed data was collected from the pavement section at Bukit Mertajam, Penang, Malaysia. The data were used to determine the stiffness of binder and corresponding stiffness of wearing and binder courses at different vehicle speeds (30, 50, 70 and 80 km/h) using analytical equations. The data of layer properties (stiffness and poison’s ratio) and axle loading (wheel load, tyre configuration) were incorporated in BISAR software to determine the horizontal tensile strain at bottom of binder layer and vertical compressive strain at top of subgrade. The strains were then used to predict pavement life passed on fatigue and rutting failure criteria. It was concluded that increasing the speed of the vehicle (from 30 km/h to 80 km/h) causes about 24% increase in stiffness modulus of wearing course. Similarly, asphalt mixture with Pen 80/100 grade bitumen has a lower stiffness modulus than Pen 60/70 grade bitumen. Furthermore, reducing vehicle speed (i.e., increasing loading time) causes a reduction in fatigue and rutting life of the pavement. Therefore, it is required to consider the speed of the vehicle while designing flexible pavement in addition to other mixed design considerations.

Study of Effective Utilization of Waste P.E.T (Plastic) and Steel Slag to Enhance the Performance of Bitumen Based Pavement

Abstract: The present work was carried out to propose the use of processed waste plastic (P.E.T) and steel slag aggregate (SSA) for the modification of bituminous mix in order to cater the need of the enhancing the performance of flexible pavements as well as to minimize the quantum plastic waste in society as they have been posing a serious threat to environment. There are two methods available namely wet and dry process of incorporating waste plastics into bituminous mixes. Research work has been carried out by adopting the wet process. In this study, wet process is carried out on the grade1 suggested by MoRTH and IRC for BC mixes. The Marshall method of mix design was adopted using Penetration grade 60/70 binder to find the optimum binder content for all conventional as well as modified bituminous mixes and to find out optimum plastic and steel slag content that can replace these conventional materials. Marshall Specimens were prepared at bitumen contents of 4.0, 4.5, 5.0% by weight to find optimum bitumen content, with P.E.T content of 0%, 4%, 6%, 8%, 10% by weight of bitumen and with steel slag aggregate content of 5%, 10% and 15% to find out respective limits and their properties. Marshall Stability, Flow value, Marshall Quotient, Air voids (Vv), Voids in Mineral Aggregates (VMA), Voids Filled with Bitumen (VFB), Retained Stability, were determined by adopting the wet process and compared with neat BC mixes. From the test results, it is clear that the Marshall Test values for modified mixes was much higher as compared to conventional bituminous mixes. Keywords: Bitumen, Aggregate, P.E.T (Polyethylene Terephthalate), Steel slag

Mechanistic Analysis of Asphalt Pavements in Support of Pavement Preservation Decision-Making

Modern roadways provide road users with a comfortable and safe ride to their destinations. Due to increasing traffic demands and maximum allowable loads, road authorities should also pay attention to the structural soundness of road pavements while seeking cost-effective and timely maintenance or minor rehabilitation activities. This means that a sustainable pavement preservation strategy is needed that includes an optimal pavement condition assessment to support the appropriate decision-making processes. To address this need, this research study proposes an approach to integrate Non-Destructive Testing (NDT) data and ground truth data to predict the long-term performance of flexible pavements. Appropriate mechanistic models that take into account the nature of Asphalt Concrete (AC) materials are used for the analysis to increase the accuracy of the results when it comes to protecting and extending pavement life. The results indicated that examining viscoelastic behavior for AC appears to be a more conservative approach for the response analysis, as well as the fatigue performance analysis, compared to the most conventional assumptions for linear elastic materials. In accordance with common sense, AC temperature was considered as a critical factor for the related investigation. Overall, it may not be a good and reliable practice to continue the process of pavement management and maintenance decisions based on the approach of only one analysis type.

Consideration of a Tack Coat Bond Strength Test to Minimize the Potential for Slippage Failures on Flexible Airfield Pavements

Slippage failures on flexible pavements are a potential problem for airports given the large wheel loads and high tire pressures of modern aircraft. While not common, when slippage failures do occur the impact can be significant on flexible pavement performance. This paper has three components: (1) case studies of slippage failures that have occurred on airfield pavements; (2) a literature review of relevant interlayer bond strength test procedures; and (3) the results of an analytical, field, and laboratory research investigation. Component (3) was conducted to assess the suitability of interface bond strength tests to evaluate the sufficiency of interlayer bond strength between lifts of asphalt pavement, either new construction or an overlay of existing pavement. The analytical study found that for a fully bonded pavement (no-slip condition), subgrade strength was the primary factor affecting horizontal stress at the interface followed by wheel load. Field cores were obtained from recently constructed asphalt pavements and brought to the laboratory for monotonic direct shear testing to determine bond strength as well as monotonic indirect tensile testing to determine mixture strength. Testing was conducted at 77°F (25°C) and 136°F (58°C). Results showed better repeatability at room temperature with similar relative performance ranking to the critical case high temperature test. Bond strength was influenced by in-place mixture density. Overall, the bond strength test method was practicable for use in field laboratories for acceptance testing.

Performance evaluation of improved flexible runway Pavement under aircraft loads

ABSTRACT Safe runway pavements are essential for the smooth landing of aircraft. Due to aircraft movements, these pavements are subjected to large dynamic loads that can cause their failure and jeopardise safety. This paper proposes the use of improved cement-based layers to enhance the performance of flexible runway pavements. The performance of such retrofitted runway pavements under both static and moving loads is investigated by experimental study and three-dimensional numerical simulations. Results indicate that the improved cement-based layers can significantly reduce surface deflections in the runways under heavy static and moving loads. Under heavy moving loads, the proposed cement-based layers can distribute the vertical stresses to the surrounding soil area, significantly reduce surface deformations and prevent failure. Findings of this research will contribute towards improved designs of runway pavements resulting in enhanced safety and failure mitigation.

Flexible pavement performance and life cycle assessment incorporating climate change impacts

Construction, maintenance and demolition of pavements are often considered the only activities impacting the environment. This paper shows that user emissions, influenced by factors such as road roughness and climate change, are also important measurements of pavement sustainability . The objective of this paper is to complete a life cycle assessment of a typical flexible pavement based on the climate change forecast by using road deterioration and user emissions analysed with the Highway Development and Management 4 (HDM-4) package. Data from South Africa were used to prove the concept. Results showed that user emissions dominate life cycle environmental impacts , and that gradual warming and drying of the atmosphere attributed to climate change is beneficial to pavement deterioration and emissions alike. Although invariably debate about the impact of climate change has negative connotations, and the reality of many negative impacts, road authorities in South Africa are fortunate that less rainfall will be beneficial.

Assessment of Performance and Maintenance of Flexible Pavement Using KENLAYER and HDM-4

This paper describes the performance of flexible pavement using the KENLAYER and Highway Development and Management (HDM-4) software for urban roads. This study includes the study area of four-lane and two-lane roads at Hyderabad city, such as Gandi Maissama to Bachupally (GB), Bachupally to Nizampet (BN), Miyapur to Bachuapally (MB), JNTU to Pragathi Nagar (JP). The distress data like rutting, fatigue, pothole, patches, and edge drop data of each roads section were taken by adopting the manual methods. The pavement deterioration model was selected and developed based on the available distress using both the software KENLAYER and HDM-4. The current study aims to forecast the performance of specific roads in order to calculate the damage ratio. It also provides the design life of the roads as per the current and future traffic based on the distress model. Further, the maintenance of the particular roads is carried out using the HDM-4 models. It is also noticed that major damage was found in Gandi Maissama to Bachupally than the other road section. This study concluded that the comparative study of different roads section and governing factors for distress along with the allowable limits of distress in each section of the flexible pavement were found. Finally, the output of KENLAYER and HDM-4 has been compared.

Developing a Maintenance Model for Pavements Vulnerable to Climate Change in South Eastern Nigeria

The South East region of Nigeria faces widespread flood during rainy seasons as a result of inadequate drainage channels, poor drainage management and most often the absence of drainage. The increase in rainfall can be attributed to climate change. Climate change has become one of the most common sources of road pavement failure in the region which leads to rapid need of maintenance as a result of flooding and this problem is becoming worse yearly. Most roads in the region suffer submergence because of flooding. In this research work, a predictive model will be developed to control maintenance of road infrastructural systems in the South-East in terms of fatigue. This work is limited to pavement behavior with respect only to fatigue life using the mechanical/elastic properties as the input parameter using additives in the established failure conditions considering Federal roads in the South East as case studies. It is also important to note that the research has a well-defined assumption within the scope to expectancy is 20 years. The loads causing pavement failure are ≥80 KN single axle. Passenger cars will not be included in the passenger. The performance of flexible pavement in real life is synonymous with performance of hot mix asphalt concrete (HMA) in the laboratory. The fatigue life of a pavement is the number of load repetitions ≥80 KN single axle load and finally, traffic loads and moisture are the only contributors to pavement damage.

Improving flexible pavement performance through suitable aggregate gradation

The objective of this study was to improve the performance of flexible pavement through suitable aggregate gradation. Thus, initially, the dynamic modulus of asphalt mixtures |E*| for different aggregate gradations were predicted, and suitable aggregate gradation was determined. Then the performance of three different pavement structures for two aggregate gradations (Mid and Suitable), using AASHTOWare Pavement ME Design 2.5. 5, were evaluated for local conditions of Izmir, Turkey. The analysis result revealed that using suitable values compared to middle values increased the |E*| and improved the rutting and fatigue resistance of all pavement structures for any traffic levels. The output of this study can be used as a guide for hot mixed asphalt mix design and pavement design based on Mechanistic-Empirical Pavement Design Guide as well.