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Concrete pavement performance models are evaluated, calibrated, and validated using field data from databases like the Long-Term Pavement Program. Conceptually, performance model predictions should match field data considering a reliability of 50%; that is, there is a 50% probability that the predictions of a certain distress indicator are higher or lower than the field data. However, modern pavements are designed for higher levels of reliability (usually 90% to 95%). Local performance model evaluation for higher levels of reliability requires a high amount of field data that traditional databases lack. Pavement management system (PMS) databases can be a useful resource for high reliability model analysis because of the large amount of data collected locally and regularly. However, when selecting and filtering field databases (of any source), the effect of censored performance data due to rehabilitation, removal from service, or modification of pavement sections is usually ignored. This paper proposes an approach for the use of PMS databases accounting for censored performance data to evaluate the accuracy of performance models' high reliability predictions. The approach is exemplified using a PMS transverse joint faulting database. Results show that by addressing the "survival issue," i.e., accounting for the censored performance data, the resulting PMS-based reliability model improves the faulting model accuracy in matching the field data for high reliability levels. [ABSTRACT FROM AUTHOR]

Featured Application: Use of large language models and AI to analyze construction safety data. The highway construction industry carries substantial safety risks for workers, necessitating thorough accident analyses to implement effective preventive measures. Current research lacks comprehensive investigations into safety incidents, relying heavily on conventional statistical methods and overlooking valuable textual information in publicly available databases. This study leverages a state-of-the-art large language model (LLM), specifically OpenAI's GPT-3.5 model. The primary focus is to enhance text-based incident analysis that is sourced from OSHA's Severe Injury Reports (SIR) database. By incorporating novel natural language processing (NLP) techniques, dimensionality reduction, clustering algorithms, and LLM prompting of incident narratives, the study aims to develop an approach to the analysis of major accident causes in highway construction. The resulting cluster analysis, coupled with LLM summarization and cause identification, reveals the major accident types, such as heat-related and struck-by injuries, as well as commonalities between incidents. This research showcases the potential of artificial intelligence (AI) and LLM technology in data-driven analysis. By efficiently processing textual data and providing insightful analysis, the study fosters practical implications for safety professionals and the development of more effective accident prevention and intervention strategies within the industry. [ABSTRACT FROM AUTHOR]

Concrete pavements develop cracks with the accumulation of fatigue damage caused by the combined effect of vehicular and environmental loadings. In Mechanistic-Empirical (ME) design, the ratio of stresses to some measure of strength is used to evaluate incremental damage, which is then related to cracking. Typically, this measure is the Modulus of Rupture (MOR) of a beam made of the same material. The flexural strength is also known to vary with the thickness of the beam. However, the variation of flexural strength due the presence of eigenstresses from temperature or moisture distributions has not received sufficient attention. A non-linear fracture mechanics model demonstrated that the thickness-adjusted flexural strength can also be used for characterising the maximum elastic stress under a linear temperature distribution. However, under a non-linear temperature distribution, the material may sustain a higher or lower maximum elastic stress than the flexural strength. To model this, a practical analytical expression for the apparent flexural strength was derived and showed excellent agreement with numerical simulations as well as with a model based on equivalent elastic deformation energy. The model was used to show that the fatigue capacity under a typical axle load varies with various non-linear temperature distributions. [ABSTRACT FROM AUTHOR]

Moisture excess in granular pavement layers can decrease pavement performance leading to moisture-related distresses. The combination of trapped water and heavy traffic loads may substantially increase pore pressure and lead to shear failure if layer hydraulic conductivity is insufficient. Currently, most pavement analysis models are unable to predict pore pressure development, so the design and evaluation methods ignore this dynamic effect which may significantly underestimate the moisture damaging effect on pavements. This paper proposes the use of Biot's poroelasticity theory for modelling fully saturated unbound materials. The proposed methodology – Poroelastodynamic Finite Integration Technique (PEFIT) – was used to analyze axisymmetric multilayered pavement structures consisting of elastic and poroelastic layers. The model was verified and validated using a well-known commercial finite element solver and field pore pressure data, respectively. A sensitivity analysis was conducted by varying critical pavement design parameters. The PEFIT analysis of a three-layer pavement system with a poroelastic base layer has shown that a decrease in base hydraulic conductivity significantly increases the maximum pore pressure, especially for high-speed loads. Results also indicate substantial pore pressure and water movement in the base layer, which may induce a potential shear failure mechanism for unbound materials. [ABSTRACT FROM AUTHOR]

During concrete pavement construction, comprehensive information on concrete strength development is necessary for knowledgeable scheduling decisions. To improve in situ strength estimation, nondestructive tests can be combined to maximize available information and increase collection efficiency. Ultrasonic testing has a higher accuracy in strength estimation for early age concrete and the external device allows for more data to be easily collected, while maturity testing can use temperature models to predict strength development. A procedure was created that combines these methods and their strength models in the laboratory for improved and increased field strength data. Using the procedure allows more data to be collected with greater accuracy and provides an adjustable, predicted strength development. This improves the efficiency of fast-track construction projects without resorting to costly alternatives by providing more information on strength development of in situ concrete than traditional strength testing or nondestructive methods individually. [ABSTRACT FROM AUTHOR]

This paper presents a new numerical procedure for the determination of the viscoelastic compliance properties of a matrix phase from a simple three-point bending test on a composite beam. The composite is modeled as elastic inclusions randomly dispersed throughout a viscoelastic matrix. It is also assumed that the spatial distribution of the inclusions in the composite is known or can be determined. Zevin's method of iterative functions is proposed for the determination of the matrix properties. Following a detailed explanation of the proposed scheme, a numerical verification is performed using three-dimensional finite-element (FE) analysis simulations. The proposed scheme was applied to the experimentally obtained creep compliance of the asphalt concrete beam. The obtained viscoelastic properties of the asphalt binder matrix phase were used as input into the FE model to simulate the behavior of the composite beam. An excellent comparison between the experimental data and the predicted beam deflections was observed. This shows that the proposed method is robust and it can be implemented to solve identification problems for viscoelastic composite materials. DOI: 10.1061/(ASCE)EM. 1943-7889.0000126 CE Database subject headings: Elasticity; Viscoelasticity; Numerical analysis; Asphalts; Mixtures; Composite materials; Pavements. Author keywords: Elasticity; Viscoelasticity; Numerical analysis; Asphalts; Mixtures; Composite materials; Pavements.

The Minnesota Department of Transportation began construction on the Minnesota Road Research Project (MnROAD) in 1991 and opened the full-scale pavement research facility to live traffic in 1994. Since the time of its construction, MnROAD, the first major test track since the AASHO Road Test of the 1950s and 1960s, has learned a number of lessons on behalf of the greater pavement community. As part of completing the first phase of MnROAD (its first ten years of operation), researchers at the University of Minnesota reviewed the many products of MnROAD's first phase for a project titled 'MnROAD Lessons Learned.' The Lessons Learned Project involved over fifty interviews, three hundred published and unpublished reports, papers, and briefs, and an online survey of pavement professionals. This paper, based on the Lessons Learned Project, presents an overview of MnROAD products of interest at the local, state, and national levels. Furthermore, the paper provides extensive references for these products in the hopes of increasing awareness of MnROAD's under-publicized contributions to pavement engineering. DOI: 10.1061/(ASCE)0733-947X(2007) 133:11 (599) CE Database subject headings: Pavement management; Databases; Minnesota.

This study considers a plate consisting of one or more layers, resting on a general clastic foundation, and subjected to a nonlinear through-the-thickness temperature distribution, together with arbitrary wheel loads. The resultant bending stress distribution in the plate is presented as the sum of the bending stresses due to the applied loading and to an equivalent linear temperature gradient, pius the pure thermal stresses due to the nonlinear part of temperature distribution. The resulting algorithm has been implemented into finite-element code ILSL2, capable of accommodating one- or two-layered slabs with a temperature distribution through the individual layers described by a linear function, a quadratic function, or explicitly provided by the user at a number of individual depths. Several examples are used to illustrate application of the method.

An algorithm for elastic reactions that can be used to compute other force or deformation variables was reviewed. This algorithm was then compared to a previous solution by Kharlab in 1963 that computes the response of structures undergoing continuous changes under time-dependent loads. This was based on his principle that if the superposition is satisfied, then (i + 1)th delayed restraint acts on the system like it was the first and only restraint.

Continuously reinforced concrete pavement (CRCP) is a widely used alternative for heavy traffic highways due to good performance and low maintenance needs. Recently, the use of short length CRCP (50-m long slabs) has been proposed for bus stops and terminals. This paper examines the structural behaviour of cracks in short CRCP. This includes analysis of the Falling Weight Deflectometer (FWD) deflections and strain gauge measurements obtained from the full-scale test sections as well as structural modelling of the pavement. An evaluation of the influence of cracks on the FWD deflection basins collected on the experimental short CRCP pavement along with FWD data collected under the Long-Term Pavement Performance programme for conventional CRCP resulted in similar behaviour between the short and conventional CRCP. Therefore, the effects of the short CRCP transverse cracks on stresses were investigated. Three ISLAB2000 models differed by the concrete base or crack model were developed and their stress predictions were compared with field stresses. An applicability of the conventional aggregate interlock model for describing the behaviour of short CRCP was evaluated as only the continuous slab (no cracks) model was able to match the field stresses. A need for re-appraisal of the PavementME structural model is also discussed. [ABSTRACT FROM AUTHOR]

This paper studies the problem of a slab-on-grade subjected to short-duration dynamic loading. The slab-on-grade system is modelled as a viscoelastic plate resting on a generalised Pasternak foundation, which accounts for the effects of inertia, damping and shear resistance. A semi-analytical forward-solution is proposed by making use of a Hankel transform in space and a finite difference method in time. To evaluate the ability of the considered model to describe the response of slab-on-grade systems, the behaviours of several pavement sections under dynamic loading are examined. A quasi-Newton inverse analysis is employed to find the model parameters by comparing the field-measured and model-calculated responses. The results show that the generalised Pasternak model can simulate the behaviour of slab-on-grade systems with a wide range of slab and grade properties. [ABSTRACT FROM AUTHOR]

A majority of existing permeable pavement installations are related to parking lots and commercial areas with low speeds and light traffic loads. During the past two decades, a tremendous amount of progress has been made with regard to the application of permeable pavements regarding mix design, hydrologic design, water quality assessment and maintenance requirements. Review of the literature revealed, however, that there are still many important questions that must be answered before permeable pavements can be fully integrated in urban roads, especially in highways with high speeds and loads. This paper summarises the major research progress in the above listed areas and identifies research needs. Research needs are summarised under four topics: (1) structural and materials property, (2) hydrologic performance, (3) water quality and (4) maintenance. Research needs are further organised based on their immediate, short-term and long-term impact. [ABSTRACT FROM AUTHOR]

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Various tests are used to characterise the strength and resilience of granular materials used in the subbase of a pavement system, but there is a limited understanding of how particle properties relate to the bulk material response under various test conditions. Here, we use discrete element method (DEM) simulations with a mechanistically based contact model to explore influences of the material properties of the particle on the results of two such tests: the dynamic cone penetrometer (DCP) and the resilient modulus tests. We find that the measured resilient modulus increases linearly with the particle elastic modulus, whereas the DCP test results are relatively insensitive to particle elastic modulus. The DCP test results are also relatively insensitive to inter-particle friction coefficient but strongly dependent on the particle shape. We discuss strengths and weaknesses of our modelling approach and include suggestions for future improvements. [ABSTRACT FROM PUBLISHER]

Functionality of concrete pavements can be restored through conventional diamond grinding (CDG) that improves ride quality and friction. Recently, an alternative diamond grinding configuration was proposed by the Institute for Safe Quiet and Durable Highway at Purdue University as part of a nationwide interest in quiet pavements. This paper discusses the field-testing of the CDG and alternative (innovative) diamond grinding as well as the pre-existing transverse tined (TT) texture at the MnROAD research facility. Acoustic properties, ride quality and friction performance of the diamond ground surfaces are compared to data obtained in the pre-existing TT surface. The initial performance of the innovative grind over a period of 3 years is also compared to that of the conventional grind and the TT surface. Test results, analysis, merits and demerits of the grinding types are also accentuated. [ABSTRACT FROM AUTHOR]

Several tests are used for the characterization of unbound materials for pavement applications. The resilient modulus has been one of the most common tests for design specification of unbound materials. The California bearing ratio (CBR) is another laboratory test that is frequently used. The dynamic cone penetrometer (DCP) test is a more common test for in situ quality assessment/quality control of unbound materials. For better connection between design and quality assurance (QA)/quality control (QC), it would be helpful to have a reliable, mechanistic method for correlating test results. This is particularly true for the use of new materials, for which there is not an extensive body of data to empirically draw such connections. This paper presents a framework for a unified approach for modeling these tests. A discrete-element method (DEM) is used to simulate the CBR test, the DCP test, and the resilient modulus test. An initial evaluation demonstrated that the simulations can account for the effect of aggregate shape, size, gradation, friction, and stiffness. As such, this methodology shows promise for the development of mechanistic-based correlation between test results. These results are presented, along with some limitations of the current model and challenges for the future. [ABSTRACT FROM AUTHOR]

Dowel bars are used at transverse joints in concrete pavements to provide load transfer, reduce faulting and improve joint performance. However, a misaligned dowel may adversely affect the performance of a joint and cause distresses in the pavement. This paper presents development, calibration, validation and application of a finite element model for behaviour analysis of various types of dowel misalignment. The model permitted extension of the laboratory testing factorial, and the results were used to quantify the effects of concrete cover and embedment length. [ABSTRACT FROM AUTHOR]

Ultrasonic tomography is an emerging method of nondestructive concrete pavement diagnostics which can be used for improved quality assurance/quality control during concrete pavement construction and assist in rehabilitation decision making. Detection of flaws using ultrasonic tomography requires significant effort and user expertise. To address these limitations, a quantitative method for determining the presence of defects in concrete pavements was developed. The proposed method is an adaptation of the recently developed impact-echo signature analysis method (IESA), which is used for comparison of impact-echo signals. The proposed two-dimensional ultrasonic tomography signature analysis (2D-UTSA) method was used to compare two-dimensional B-scans obtained using a commercial test system in field trials at the Minnesota Rd. Research Facility and the Federal Aviation Administration's National Airport Pavement Test Facility. Analysis of the results showed that the 2D-UTSA method is capable of identifying subsurface defects. [ABSTRACT FROM AUTHOR]

In practice, it has been observed that the method of pervious concrete void maintenance depends on which machines or vehicles the owners have available. This research compares the abilities of three common municipal utility vehicles-a vacuum truck with a flexible, 200-mm (8-in.) hose; a vacuum street sweeper; and a regenerative air street sweeper-to remove clogging material from the voids of in-service pervious concrete pavements. By using optical microscopy, it was found that clogging materials rarely migrate into voids deeper than 12.7 mm (1/2 in.) from the surface. Furthermore, all three machines were able to remove clogging materials that were located within 3.18 mm (1/8 in.) of the surface. The clogging material that was located deeper than 3.18 mm (1/8 in.) remained within the voids but was likely disturbed by either the suction or the forced air of the maintenance vehicles. [ABSTRACT FROM AUTHOR]

Pavement design optimisation is an active area of research. Due to a large number of parameters, such as thickness of layers, material properties, climatic conditions, affecting pavement performance, it is usually not feasible to determine an optimal design using a trial and error approach. In order to make the design calculation computationally tractable, the process can be posed as an optimisation problem. Previous investigations in this vein have suffered from the limitations of a specific pavement analysis tool, specific design goals and specific optimisation algorithms. This paper presents a general computational framework, combining Mechanistic-Empirical Pavement Design Guide and Design Analysis Kit for Optimisation and Terascale Applications, to overcome these shortcomings. The framework's promise is demonstrated through its application to a minimum cost pavement design problem using both direct and surrogate-based (SBO) optimisation approaches. The SBO formulation is shown to achieve significant savings in required computational time with a minimal loss of accuracy in the determined optimal design. [ABSTRACT FROM AUTHOR]

Dowels are inserted at the mid-depth of joints in jointed concrete pavements that are exposed to heavy loading to provide load transfer and reduce pumping and faulting. Dowel alignment tolerances in North America have traditionally been strict, although not based on substantial performance data. In this paper, new laboratory testing methods are proposed for evaluation of the effects of dowel misalignment on concrete joint behavior. In these tests, dowels with various levels of rotations and translations were subjected to pullout and shear loading. It was found that dowel misalignment does not have a significant effect on pullout and shear forces for certain ranges of misalignments, which far exceed the tolerances recommended by the Federal Highway Administration. At the same time, it was found that extreme cases and combinations of misalignment resulted in a significant decrease in initial stiffness and shear capacity. Therefore, there is a need for the establishment of rational alignment tolerances. The results of this study provide important information for the development of such tolerances. [ABSTRACT FROM AUTHOR]

An existing finite element program—ISLAB2000—was modified to allow for the analysis of horizontally restrained and unrestrained portland cement concrete (PCC) pavement slabs with partial depth cracks. To simulate a partial-depth crack, special line spring elements were added to the ISLAB2000 finite element code. Previously published relationships between spring elements stiffness and crack depth were used for formulating the element stiffness matrix of the line spring elements and to calculate stress intensity factors after solving the system of finite element equations.Several example problems of partially cracked PCC slabs subject to typical highway loadings were solved to verify this newly developed finite element model termed ISLAB2005. The impact of crack depth and base friction parameters on slabs stresses and deflections was investigated. On the basis of this analysis, ISLAB2005 was found to be a reliable tool for analysis of partially cracked pavements that are either restrained or unrestrained from horizontal movements. [ABSTRACT FROM AUTHOR]

Ultra-thin concrete overlays or ultra-thin whitetopping (UTW), are an attractive alternative to traditional practices for the rehabilitation of asphalt pavements. However, it is widely accepted that the exiting pavement should have substantial stiffness to make a UTW a rehabilitation option. This paper re-examines this hypothesis using the performance results and structural evaluation of two experimental sections in Brazil. It is shown that structural contribution of the existing pavement is important for good performance of UTW. However, it appears that the ability of the existing pavement to ensure composite action of the individual slabs in the UTW is more important than its contribution to the flexural stiffness. [ABSTRACT FROM AUTHOR]

Abstract: In a recent survey, the durability and condition of 29 in service pervious concrete pavements built in a wet, hard freeze environment were assessed, and 33 core samples were collected. Following up on this survey, this paper identifies some of the common subsurface distresses observed in the core samples with optical microscopy instruments. In the distressed samples, cracks went through the aggregate, paste, and interfacial transition zone (ITZ). The cracks were similar to cracks in conventional concretes that formed due to known freeze/thaw damage. In addition to cracking patterns, it was discovered that none of the 33 pervious concrete samples contained the recommended quantity or spacing of entrained air bubbles. There was a lack of entrained air bubbles despite the addition of air-entraining admixtures to all of the pervious concrete mixtures. It is unknown if the lack of entrained air bubbles contributed to the cracks in the pervious concretes. [Copyright &y& Elsevier]