Showing papers by "Karim Chatti published in 2012"

Estimating the Effects of Pavement Condition on Vehicle Operating Costs

Abstract: This report presents models for estimating the effects of pavement condition on vehicle operating costs. These models address fuel consumption, tire wear, and repair and maintenance costs and are presented as computational software on the accompanying CD-ROM, CRP-CD-111, to facilitate use. The material contained in the report should be of immediate interest to state pavement, construction, and maintenance engineers; vehicle fleet managers; and those involved in pavement investment decision processes and financial aspects of highway transportation.

Prediction of Transient and Steady-State Flexural Fatigue Crack Propagation in Concrete Using a Cyclic R-Curve

Abstract: Fatigue damage in plain portland cement concrete is a nonlinear process that exhibits two distinct crack stages: a deceleration stage (transient crack growth) and an acceleration stage (steady-state crack growth). In the past, either the transient crack growth stage was completely neglected or was described using a power law that used crack extension as its argument. This works well for constant amplitude loading and for one geometry. However, to extend the fatigue prediction to variable amplitude loading, and also account for size effect, a fatigue crack resistance curve should be obtained so that the bridging stresses behind the crack tip can be calculated. In this paper, a new method has been developed to determine the fatigue crack resistance curve from crack rate and stress intensity data obtained from three point bending single edge notched specimens. The results of this study suggest that the fatigue crack resistance curve has a similar shape to the quasi-static crack resistance curve. Primarily, t...

A Self-powered Sensing System for Continuous Fatigue Monitoring of In-service Pavements

Abstract: The objective of this paper is to present an overview of on-going work aimed at the development of a sensing system that can be applied toward the long term monitoring of pavement structures. The paper addresses the different challenges related to the successful development and implementation of the system for pavement application. The novel module consists of a miniaturized battery-less wireless sensor capable of detecting the long-term strain history of the pavement structure. It is based on the integration of piezoelectric transducers with an array of ultra-low power floating gate computational circuits. The paper is split into four sections. First, a summary of the development of the sensor electronics is provided. Then, a description of the development of a reliable packaging system that ensures structure integration of the sensor, reasonable survivability under construction conditions, and longevity in harsh environments, is presented. Also, a damage prediction algorithm to estimate the remaining life of the pavement from the sensor output data is discussed. Finally, the use of a probabilistic based interpolation technique for the estimation of full field strain distributions, using measured data from a limited number of implemented sensors, is investigated in the context of exploring the feasibility of large networks deployment.

Impact of Three State Practices on Effectiveness of Hot-Mix Asphalt Overlay

Abstract: The effectiveness of pavement treatments is a function of several factors, including material quality, design, distribution of pavement condition states (conditions and rates of deterioration) before treatment, and construction quality. Because of these factors, state highway agencies have established estimates of treatment service lives with significantly wide ranges. These wide ranges make the calculation of treatment benefits or effectiveness a difficult task unless the role of each factor that affects service life is well understood. This study analyzed the impacts of the state of the practice of Colorado, Louisiana, and Washington on the effectiveness of thin (< 2.5 in.) hot-mix asphalt (HMA) overlay treatment. This paper reports that analysis of time-series pavement condition and distress data of previously treated pavement sections can be tabulated in a matrix format to demonstrate a snapshot examination of past practice. Such matrices are called treatment transition matrices (T2Ms). The data in th...

Relating Flexible Pavement Acceptance Criteria to Performance Using Mepdg Simulations and Piecewise Cubic Spline Interpolation

Abstract: The performance of the highway system is inevitably linked to its quality of design and construction. To control the quality of construction, elaborate Quality Assurance (QA) programs have been developed by highway agencies based on statistical sampling and acceptance procedures to ensure that the work is in accordance with the plans and specifications. The QA procedure is intended to ensure that the constructed pavement would perform well during its design life. However, numerous field investigations and research studies over the years have identified a gap in our understanding of the relationship between the QA test results and pavement performance (fatigue cracking, rutting, etc.). This paper is intended to present the framework for developing an understanding of the relationship between QA tests and flexible pavement performance, which is essential for developing Performance Related Specifications (PRS). In the first part of the paper, the Michigan Department of Transportation's (MDOT) QA pro...

Impacts of Pavement Condition Analysis Length on Treatment Transition Matrices and Treatment Benefits

Abstract: In general, pavement treatment actions transform pavement segments from one condition state to another. The transformation could be summarized using treatment transition matrices (T2Ms) that indicate the probability that a pavement segment transfers from one condition state to another. This probability is a function of the before treatment pavement condition state and the treatment type. Some State Highway Agencies (SHAs) collect and store pavement condition data along 0.1 mile pavement survey or segment lengths while others use different survey lengths. The data variability makes it difficult to model the pavement conditions of each segment over time and to assess its transition from one condition state to another. It has been suggested that increasing the pavement length over which the conditions are analyzed may decrease the data variability and improve the modeling of pavement conditions over time. Nearly 445 miles of flexible pavements that were subjected to asphalt concrete (AC) overlay and 349 miles of the same subjected to mill and fill were analyzed to determine the effects of the pavement analysis length on the T2Ms. In the analysis, the data of each 0.1 mile pavement segment were used to generate analysis lengths of 0.1, 0.4, 0.7, and 1.0 miles. Results of the analysis are presented and discussed in this paper. It is shown that, for IRI and rut depth data, the T2Ms are independent of the pavement analysis length. However, T2Ms based on cracking data are a function of the pavement analysis length.

Forward Calculation of Subgrade Modulus Using Falling Weight Deflectometer Time Histories and Wave Propagation Theory

Abstract: This paper presents a method for forward-calculating the subgrade modulus from the transient response under a Falling Weight Deflectometer. The method is based on wave propagation theory and uses the formulation for spectral element method to calculate the surface deflection of a semi-infinite halfsapce. Rayleigh wave velocity is calculated using the location of the far sensors and the times corresponding to their peak response. The ratio of Rayleigh and shear wave velocities was found to be 0.81 for axisymmetric loading. This allows for calculating the shear wave velocity, which can then be used to calculate the shear modulus, then the elastic modulus of the subgrade. Results were verified by comparing them to those obtained using a dynamic finite layer solution. A sensitivity analysis was conducted on the depth to bedrock and its stiffness. The results show that the effect of bedrock becomes insignificant if the depth to bedrock is greater than about 5m (18 ft).

Long-term pavement performance effectiveness of preventive maintenance treatments using Markov chain algorithm

Abstract: In the Long-term Pavement Performance (LTPP) study, the SPS-3 experiment was designed to assess the performance of different flexible pavement maintenance treatments, relative to the performance of untreated control sections. The experiment consists of a control section and four maintenance treatments: thin overlay, slurry seal, chip seal, and crack seal. Several studies in the past have evaluated the effectiveness of the maintenance treatments; however, there is a need to re-evaluate the results as more performance data become available. This paper uses Markov chain algorithm (MCA) to evaluate the effectiveness of maintenance treatments at the network level. For each treatment, the transition matrices were determined from the observed time series performance data for ride quality, fatigue cracking, and rutting. The advantages of using MCA includes the ability to dynamically model pavement deterioration and improvement at the same time, evaluate the impact of initial pavement conditions on the short- and long-term performance, and relative comparison of pavement performance among different maintenance treatments. The results show that different maintenance treatments have varying effectiveness depending on the distress type. For example, thin overlay is more effective in the long-term for improving IRI and rutting while chip seal seems to be a better choice in case of alligator cracking. Generally, different seals considered in the SPS-3 experiment are more effective when applied to a network in good condition while overlay is more effective for a network in poor condition.

Pavement Treatment Transition Matrices: Reality Check on Treatment Practices

Abstract: When a pavement section is subjected to preservation or rehabilitation treatments, its surface conditions transfer from one condition state before treatment to another after treatment. This transformation is a function of the condition state before treatment, the treatment type and timing, the project boundaries, and the quality of construction. The pavement surface conditions along a project vary substantially from one point to the next. Hence, a typical pavement project consists of several condition states that will be transferred to another set of condition states due to the treatment. The probability of such transformation of each pavement segment from one condition state to another populates the cells of the treatment transition matrix. In this study, the before and after treatment distributions of 0.1 mile pavement segments along flexible pavement projects in the State of Louisiana that were subjected to asphalt concrete overlay, mill and fill, and single and double chip seals were studied. Treatment transition matrices were formed and analyzed. The results are presented and discussed in this paper. It is shown that treatment transition matrices can be used to study the health of the pavement network, construction quality, the differences in the state-of-the-practice between the various regions within the state, the benefits of the treatments, and to establish the parameters for design-build warranties. It is also shown that the state-of-the-practice for the selection of treatment type is not dependent on the before treatment distribution of the condition states of the 0.1 mile pavement segments.

Strategy Analysis Using Treatment Transition Matrices of In-service Pavement Condition Data

Abstract: One of the objectives of a comprehensive pavement management system is to deliver to the public cost effective, safe, and conveniently accessible road network. This objective could be accomplished through a series of treatments to maintain, upgrade, and improve the condition and safety of the road network within a given budget constraint. The cost effectiveness of each treatment is a function of the selected treatment types, project boundaries, and time of action. The selection of treatment types must be based on the pavement surface condition and its rate of deterioration prior to treatment, the causes of distresses and the impact of each treatment or treatment strategy on the health of the network. The long term effect of pavement deterioration could be analyzed using Markov Chain Algorithm (MCA) utilizing a pavement network deterioration matrix. In reality such deterioration matrix applies, on a yearly basis, to about 90% of the pavement network having the do-nothing alternative. The problem is that MCA cannot be used when a certain percent of the pavement network is treated on a yearly basis. Thus, MCA modifications needs to be developed to reflect the long-term effects of a given treatment strategy on the pavement network. Such modifications are based on treatment transition matrices expressing the probability of transitioning pavement sections from one condition state before treatment to another state after treatment. This paper presents and discusses the formation of the treatment transition matrices, and a developed algorithm for the modification of the MCA and its advantages and shortcomings.

Impact of road roughness features on damage to transported goods

Abstract: In this paper, we propose a novel approach to estimate the damage induced to transported goods by roughness features. The approach proposed herein uses a mechanistic-empirical approach to conduct product fragility assessment using numerical modeling of vehicle and product vibration response. A half-truck model was used to simulate vehicle vibrations. The principle of conservation of momentum (inelastic shocks) was used to estimate damage to goods. The analysis of three case studies for horticultural produce showed that: air suspensions cause less damage to the transported goods than steel suspensions; shorter spacing between faults in jointed concrete pavements will cause less damage to the transported goods in trucks with steel suspension; low speed will cause more damage to transported goods in trucks with steel suspensions than higher speed; and more breaks on the road will cause more damage to the transported goods. The approach reported in this paper could help in better estimating vehicle operating costs at the project and network levels.

Modeling Pavement Conditions of Multilane Roads with Measured Driving Lane Data

Abstract: In the past, highway authorities have selected pavement treatment type on the basis of the driving lane conditions and have applied the same treatment to all lanes. Recently, authorities started applying different treatments to the driving and passing lanes at different times. Because of costs, most highway authorities collect only the driving lane pavement condition data. Therefore, the passing lane pavement conditions need to be modeled with the driving lane data. To address this need, time series pavement condition and distress data along the driving and passing lanes of the Minnesota Road Research Project were obtained. The data were analyzed to develop and verify methodologies to estimate the passing lane conditions and distresses accurately with the use of the measured driving lane data. The methodologies are based on the fact that most pavement distresses are caused by material and environmental factors and by traffic loads. The effects of the first two factors are similar on adjacent driving and p...

Plain Concrete Cyclic Crack Resistance Curves under Constant and Variable Amplitude Loading

Abstract: Concrete pavement structures are subjected to a complex combination of environmental and traffic loads which produce a unique distribution of stresses at the critical mid-slab edge Moreover, the fracture propagation caused by this unique distribution of stresses is a complex process because it is both size and load history dependent In this study, a series of quasi-static, constant and variable amplitude fatigue tests on simply supported single edge notched beam specimens were conducted It is shown that variable amplitude testing can providea comprehensive assessment of fatigue life because the R-ratio, peak stress intensity, and load history effects can be assessed The results of this study also suggest that the fatigue resistance curve under variable amplitude has a similar quality to that under constant amplitude loading; there is a positive decreasing slope that asymptotes to a zero slope condition beyond the critical crack extension However, the results show the magnitude of the critical crack extension and the maximum fracture resistances are not the same under the two different loading conditions