Existing Pavement Conditions Research Articles

Effect of existing pavement condition and overlaying strategy on the reflective cracking resistance of asphalt pavement

Overlaying becomes more and more popular as a method to improve the driving quality and structural integrity of the pavement. The existing pavement condition needs to be evaluated when selecting the proper overlaying strategy. In this paper, the existing pavement condition of four field pavement projects was surveyed and the crack amount and crack pattern were monitored before asphalt overlaying and 1–2 years after the overlaying paving. It was found that thermal crack was initiated within two pavement projects, whereas the reflective crack was observed within other pavement projects with transverse cracks in the existing pavement. The potential factor that could induce the above field crack pattern difference was identified. Additionally, the Finite Element Method (FEM) analysis was conducted to study the effects of existing pavement conditions on crack propagation and the crack resistance of a new overlaying strategy. Results show that the J-integral of crack tip is increased and then decreased with the increase of crack length. The higher modulus of the existing layer leads to a larger value of J-integral while the aging effect of overlay contributes to delay crack propagation of the existing layer. The crack width of the existing layer has less effect on the J-integral at the crack tip of overlay. In addition, a new overlaying strategy is proposed to alleviate the reflective crack, in which multi-layer overlays are constructed and the geogrid is employed and placed between the existing pavement layer and the bottom layer of overlay, as well as other interfaces between any two adjacent overlays. Such a strategy is found to be effective in reducing reflective cracks by using simulative modeling.

Investigation on Causes of Pavement Failure and Its Remedial Measures

Abstract: Pavement failure is defined in terms of decreasing serviceability caused by the development of cracks and ruts. Before going into the maintenance strategies, we must look into the causes of failure of bituminous pavements. Failures of bituminous pavements are caused due to many reasons or combination of reasons. Application of correction in the existing surface will enhance the life of maintenance works as well as that of strengthening layer. It has been seen that only 3 parameters i.e., unevenness index, pavement cracking and rutting are considered while other distresses have been omitted while going for maintenance operations. Along with the maintenance techniques there are various methods for pavement preservation which will help in enhancing the life of pavement and delaying of its failure. The purpose of this study was to evaluate the possible causes of pavement distresses, and to recommend remedies to minimize distress of the pavement. The report describes lessons learnt from pavement failures and problems experienced during the last few years on a number of projects in India. Based on the past experience’s various pavement preservation techniques and measures are also discussed which will be helpful in increasing the serviceable life of pavement. A comprehensive literature concerning the factors of road deterioration, common road defects and their causes were reviewed. The investigation involved field survey and laboratory testing on those projects to examine the existing pavement conditions. The results revealed that the roads investigated experienced severe failures in the forms of cracks, potholes and rutting in the wheel path. The causes of those failures were found mainly linked to poor drainage, traffic overloading, expansive subgrade soils and the use of low-quality materials in construction. Based on the results, recommendations were provided to help highway engineers in selecting the most effective repair techniques for specific kinds of distresses.

A framework for evaluation of existing pavement conditions and selection of feasible maintenance/rehabilitation alternatives; a case study in some routes of Livingston Parish in the state of Louisiana

This study presents a step-by-step framework process/general guideline for the process of project evaluation, identify, document, and evaluate the existing pavement conditions plus evaluate the most feasible maintenance/rehabilitation alternatives for flexible roads. The presented framework could be significantly useful for extending the service life of the pavement, based on their accurate time of application. The presented framework consists of six classified steps to evaluate the existing condition of the pavement, assessing the cost-effectiveness of different maintenance or rehabilitation techniques by conducting Life Cycle Cost Analysis and selecting feasible alternative techniques according to distress types in the flexible pavements. As of the framework, four existing pavements located in Livingston parish in the state of Louisiana have evaluated in detail. Finally, at least two feasible alternatives have suggested for each subsection roads and most cost-effective alternative techniques scored according to assigned weighting factors. Although Different strategies are using by various highway agencies to evaluate the strategy of selection of the appropriate alternative, which is different in the details, the proposed framework could evaluate the uncertainties associated with infrastructure conditions plus determining the optimal inspection, maintenance, and rehabilitation decision policies. This study presents that Micro-surfacing and thin overlay techniques found the most common techniques for the case studies sections, which are according to the Louisiana Department of Transportation and Development common treatment selection strategy.

Traffic volume and load data measurement using a portable weigh in motion system: A case study

Traditionally, traffic loading characteristics are collected for pavement design and performance prediction purposes using permanent roadside weigh-in-motion (WIM) stations. However, high installation and maintenance costs associated with these permanent WIM stations dictate that their deployment be mostly limited to major highways, such as the interstate network. Quite often however, pavement damage on high volume rural highways with heavy truck proportions is more severe than anticipated, and there is no effective way of quantifying the traffic loading on these highways. Therefore, this study was conducted to evaluate the potential application of portable WIM systems as a means for bringing the WIM technology to these high volume rural highways. A portable WIM unit was deployed in the Texas overweight corridor in Hidalgo County (Pharr District) near the USA-Mexico border on highway FM 1016 for collecting traffic data for a minimum of three weeks in each direction. The collected traffic data were analyzed to generate traffic parameters such as volume, load spectra, and overloading information both in terms of the gross vehicle weight (GVW) and axle weight. The computed traffic parameters were successful in partially explaining some of the existing pavement conditions on this highway. Overall, the study findings indicated that the portable WIM unit can be used as a convenient and cost-effective means for collecting reliable traffic information for design, analysis, and monitoring purposes. However, proper in-situ calibration of the portable WIM unit at each site is imperative prior to any real-time traffic data collection.

Long-Term Performance of Diamond Grinding

Diamond grinding (DG) has been used by various districts to improve skid resistance (reduce accidents and fatalities) and improve ride quality [reduce international roughness index (IRI)], with the added benefit of reducing tire/pavement interface noise. The Texas Department of Transportation has used DG on both jointed concrete pavement (JCP) and continuously reinforced concrete pavement (CRCP). This study performed crash accident analysis both before and after DG on a recent project section. After the completion of DG, the occurrences had reduced by approximately 62 and 46% for fatalities and incapacitating injuries, respectively. There was an average IRI reduction of approximately 44 in. (0.70 m/km), or 40%, immediately after treatment. This study also analyzed eleven projects to derive a statewide trend on various surface characteristics of pavements due to DG, with the oldest section studied approximately eight years after treatment. Immediately after DG, the average skid number (SN) increased 5.6, or by about 30%. Depending on the existing pavement conditions, the range of the increase in SN varies from 1 to 18. Similarly, there was an average IRI reduction of approximately 0.95 m/km (60 in./mi) immediately after the DG, or about 40%. Depending on the existing pavement conditions, the range of IRI reduction varies from 0.32–1.94 m/km (20–122 in./mi), or 17–57%. For deterioration rate under the effect of factors such as time and traffic, each year the SN decreases by approximately 2.0 and IRI increases by approximately 0.03 m/km (1.7 in./mi).

Asphalt Binder Grading System by Indirectly Estimated Parameters and Relationship to Performance Related Properties of Asphalt Mixture

Nowadays, there have been initiative ideas to improve current use of grading system in Thailand by replacing with SUPERPAVE grading system. Unfortunately, such system requires complex and expensive equipment which is unavailable in Thailand. The knowledge in understanding the implementation of the system is also limited. Moreover, the SUPERPAVE specification is particularly based on the pavement conditions in USA. Therefore, a development of the performance grading system using indirectly estimated parameters related to pavement performance is proposed in this study. According to the existing pavement conditions in Thailand, the eligible performance related properties are examined and the acceptable limits for the acceptance of asphalt cement are determined. Additionally, the preparation of asphalt mixtures from the newly graded asphalt cement is investigated for their performance related properties in Thai traffic and climate conditions. After the validation of such developed system, it has been found that the proposed performance grading system can be satisfactorily used to classify the binders by its performance. Results of the proposed system are also comparable with the SUPERPAVE system. Finally, the proposed system can be used as a transition before obtaining the sufficient equipment and gaining sufficient understanding for SUPERPAVE implementation without using any complex and expensive equipment.

Staged survival models for overlay performance prediction

Asphalt concrete (AC) resurfacing is used by highway agencies to maintain and improve existing pavement conditions. With a large portion of their budgets being spent on road maintenance and rehabilitation, the agencies are interested in identifying the optimal timing of resurfacing and its life expectations. Using Kentucky's pavement management data, the research as presented by this paper investigated the procedures and methods of establishing thresholds and developing performance prediction models for AC overlays. Both transition probability matrix and data plots were used to investigate the performance trend of overlays. Based on the trend, two stage survival models were proposed to predict the resurfacing cycles. The first stage model can be used to predict the useful life of an overlay before a new resurfacing is required, while the second one can be used to predict the time window during which the new overlay must be applied to avoid accelerated pavement deterioration.

In Situ Evaluation of Layer Stiffnesses of Airport Pavements by Crosshole Seismic Tests

Many runways and taxiways in major international airports have been in service for 20 years or more. To manage this pavement system effectively, it is important to determine existing pavement conditions and to predict remaining service life. These two aspects are some of the challenges facing airport and highway engineers alike. By knowing the rate of change since the commissioning of the runway, one may be able to predict the remaining life of the pavement. Optimizing the useful life of the pavement is an effective way of managing the pavement and maximizing the benefit of the capital investment. To evaluate existing pavement conditions at the Dallas–Fort Worth (DFW) International Airport, a testing procedure was used that had been developed at The University of Texas at Austin using seismic waves. This procedure involves performing crosshole seismic tests with a system tailored to perform independent measurements in all layers of the pavement profile, that is, independent stiffness measurements in the surface, cement-treated base, and lime-stabilized subbase layers as well as the subgrade. The cross-hole procedure proved to be very effective for measurements of both runway and taxiway pavements. The test procedure, field equipment, and test results are presented herein. Issues considered in the study include how each layer stiffness has changed with more than 20 years of service at DFW; what is the relative stiffness change in each of the layers between trafficked and untrafficked areas; and how have the stiffnesses of the different layers beneath the joints changed relative to these same layers beneath the midslab areas.

Initial Improvement in Ride Quality of Jointed, Plain Concrete Pavement with Microsurfacing: Case Study

Safety, cost, ride quality, and performance are characteristics of pavement systems that are considered high-priority customer demands by transportation agencies throughout the world. Ride quality is the characteristic most notable to the traveling public. Throughout the United States, numerous state and federal agencies have developed specifications that require that road contractors meet a minimum level of ride quality before a pavement is approved for payment. Studies have shown that initial (as constructed) ride quality is an important factor in determining overall serviceability and length of time to rehabilitation or reconstruction. A case study in Cowley County, Kansas, in which the ride quality of an existing jointed, plain concrete pavement was significantly improved by the placement of a thin, polymer-modified, asphalt-emulsion microsurfacing system, is described. The existing pavement conditions, the construction techniques used by the contractor, and the smoothness measurements before and after construction are noted and discussed. It was found that a marked reduction in roughness can be accomplished with unique construction techniques and microsurfacing.

Mechanistically Based Flexible Overlay Design System for Idaho

A study was conducted on a mechanistically based overlay design procedure that incorporates the in situ pavement layer modulus values evaluated by deflection-based nondestructive testing using falling weight deflectometer data. The proposed overlay design procedure addresses the seasonal variation in the state of Idaho and adjusts the modulus values accordingly. The performance of the pavement is calculated in terms of critical strains based on the elastic multilayer theory. The study adopts the Asphalt Institute fatigue and rutting failure criteria to calculate the life of the pavement. Damage analysis is performed based on the past and expected future traffic to calculate the required overlay thickness. The procedure developed has been implemented in an event-driven, user-friendly computer program FLEXOLAY, which runs in the DOS environment. The program was tested and compared with other overlay design methods using pavement sections from the state of Idaho. The overlay thickness determined by FLEXOLAY was found to be close to some of the existing methods and far from others, depending on the existing pavement conditions.

Mechanistically Based Flexible Overlay Design System for Idaho

A study was conducted on a mechanistically based overlay design procedure that incorporates the in situ pavement layer modulus values evaluated by deflection-based nondestructive testing using falling weight deflectometer data. The proposed overlay design procedure addresses the seasonal variation in the state of Idaho and adjusts the modulus values accordingly. The performance of the pavement is calculated in terms of critical strains based on the elastic multilayer theory. The study adopts the Asphalt Institute fatigue and rutting failure criteria to calculate the life of the pavement. Damage analysis is performed based on the past and expected future traffic to calculate the required overlay thickness. The procedure developed has been implemented in an event-driven, user-friendly computer program FLEXOLAY, which runs in the DOS environment. The program was tested and compared with other overlay design methods using pavement sections from the state of Idaho. The overlay thickness determined by FLEXOLAY was found to be close to some of the existing methods and far from others, depending on the existing pavement conditions.

Initial Improvement in Ride Quality of Jointed, Plain Concrete Pavement with Microsurfacing: Case Study

Safety, cost, ride quality, and performance are characteristics of pavement systems that are considered high-priority customer demands by transportation agencies throughout the world. Ride quality is the characteristic most notable to the traveling public. Throughout the United States, numerous state and federal agencies have developed specifications that require that road contractors meet a minimum level of ride quality before a pavement is approved for payment. Studies have shown that initial (as constructed) ride quality is an important factor in determining overall serviceability and length of time to rehabilitation or reconstruction. A case study in Cowley County, Kansas, in which the ride quality of an existing jointed, plain concrete pavement was significantly improved by the placement of a thin, polymer-modified, asphaltemulsion microsurfacing system, is described. The existing pavement conditions, the construction techniques used by the contractor, and the smoothness measurements before and after construction are noted and discussed. It was found that a marked reduction in roughness can be accomplished with unique construction techniques and microsurfacing.

Evaluation of Pavement Bearing Characteristics Using Florida Limerock Bearing Ratio Test

A laboratory study performed to evaluate pavement bearing characteristics by the Florida limerock bearing ratio (LBR) test is presented. The LBR is a modification of the California bearing ratio test and has been widely used in Florida for the design of pavement structures. The LBR evaluation is part of a larger research project studying existing pavement conditions in Florida. A field experimental program was recently conducted on 20 selected pavement sites across the state of Florida. The LBR test was performed on pavement soils obtained from the field test sites. The LBR test results were analyzed and compared with the field test results. The AASHO Road Test layer coefficient values (a2) and soil support values (SSVs), which have become classic reference values over more than two decades, were evaluated by using the LBR and field test results. It was concluded that the LBR values could be used to estimate the SSVs for the design of flexible pavements in Florida. The correlation relationships between the LBR values and SSVs were evaluated to better characterize the pavement structures in Florida.

Evaluation of Pavement Bearing Characteristics Using Florida Limerock Bearing Ratio Test

A laboratory study performed to evaluate pavement bearing characteristics by the Florida limerock bearing ratio (LBR) test is presented. The LBR is a modification of the California bearing ratio test and has been widely used in Florida for the design of pavement structures. The LBR evaluation is part of a larger research project studying existing pavement conditions in Florida. A field experimental program was recently conducted on 20 selected pavement sites across the state of Florida. The LBR test was performed on pavement soils obtained from the field test sites. The LBR test results were analyzed and compared with the field test results. The AASHO Road Test layer coefficient values (a2) and soil support values (SSVs), which have become classic reference values over more than two decades, were evaluated by using the LBR and field test results. It was concluded that the LBR values could be used to estimate the SSVs for the design of flexible pavements in Florida. The correlation relationships between the LBR values and SSVs were evaluated to better characterize the pavement structures in Florida.