Journal Article•
Benchmarking the structural condition of flexible pavements with deflection bowl parameters
01 Jun 2008-Journal of The South African Institution of Civil Engineering (South African Institution Of Civil Engineering (SAICE))-Vol. 50, Iss: 2, pp 2-9
TL;DR: A semi-mechanistic, semi-empirical analysis technique has been developed in South Africa in terms of which deflection bowl parameters, measured with the FWD, are used in a relative benchmarking methodology in conjunction with standardised visual survey methodology to give guidance on individual layer strengths and pinpoint rehabilitation needs.
Abstract: The falling weight deflectometer (FWD) is used worldwide as an established, valuable, nondestructive road testing device for pavement structural analyses. The FWD is used mostly for rehabilitation project level design investigations and for pavement management system (PMS) monitoring on a network basis. In project level investigations, design charts based on both empirical relations and mechanistic or theoretically based approaches are often used to provide structural evaluations and rehabilitation options. The full mechanistic approach normally uses multi-layer linear elastic theory and back-calculation procedures that have come under scrutiny owing to the inaccuracy of results. A semi-mechanistic, semi-empirical analysis technique has been developed in South Africa in terms of which deflection bowl parameters, measured with the FWD, are used in a relative benchmarking methodology in conjunction with standardised visual survey methodology to give guidance on individual layer strengths and pinpoint rehabilitation needs. This benchmark methodology enables the determination of the relative structural condition of the pavement over length and in depth without the requirement for detailed as-built data. A further correlation study with calculated surface moduli and deflection bowl parameters is presented here for granular base pavements, which can enhance benchmarking methodology.
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TL;DR: A relationship between deflection bowl parameters derived from Falling Weight Deflectometer and two pavement performance indices are developed by the use of Artificial Neural Network (ANN) and regression models which indicate that using both IRI and PASER indices leads to accurate structural pavement evaluation.
Abstract: Evaluation of pavement condition, which determines pavement maintenance and rehabilitation necessities, is inevitable using structural or non-structural methods. Since factors such as cost and time required for testing limit the use of structural assessment devices, the development of cost-effective methods should be investigated. In this paper, a practical solution has been presented for pavement structural evaluation which is considered as a useful method for assessing pavement layers condition and identifying rehabilitation needs. With this in mind, we developed a relationship between deflection bowl parameters derived from Falling Weight Deflectometer (FWD) and two pavement performance indices, International Roughness Index (IRI) and Pavement Surface Evaluation and Rating index (PASER), by the use of Artificial Neural Network (ANN) and regression models. To obtain the required data, project field surveys were conducted from 318 sections of the main roads of Kermanshah and Ilam provinces in Iran. The results show that our model provides a satisfactory correlation between IRI, PASER, and structural indices which are based on deflection measurements. By comparing the results of ANN and regression models, the superiority of ANN performance over non-intelligent models is appreciable. The findings of this study indicate that using both IRI and PASER indices leads to accurate structural pavement evaluation.
48 citations
TL;DR: In this article, an integrated regression analysis is conducted considering both ground penetrating radar (GPR) and falling weight deflectometer (FWD) data with the aim to develop a relationship between GPR-estimated AC thicknesses and FWD deflection indexes.
Abstract: The pavement engineering community has consistently drawn its attention to a broadened utilization of advanced Non-Destructive Testing (NDT) systems for pavement evaluation. Amongst these systems, the Falling Weight Deflectometer (FWD) is designed to measure surface deflections and assess the pavement structural condition, while Ground Penetrating Radar (GPR) is utilized to estimate pavement layers’ thicknesses. An integration of the capabilities of these two separate systems has been considered a powerful resource in pavement evaluation. With this in mind, the present study aims to investigate whether this integration could result in the utilization of the derived FWD deflection data to directly assess pavement layers thicknesses. For the research, an integrated regression analysis is conducted considering both GPR and FWD data with the aim to develop a relationship between GPR-estimated AC thicknesses and FWD deflection indexes. The developed relationship is calibrated considering both GPR and core thicknesses and further validated yielding an equivalent and satisfactory performance, with thickness prediction errors around 10%. This finding produces evidence in support of the statement that deflection data is capable of roughly producing pavement layer thicknesses. Such an approach could suggest a practical and cost-effective pavement evaluation tool, when the procurement and transportation logistics of implementing multiple and expensive equipment may be a critical issue.
32 citations
TL;DR: The application of non-destructive testing devices such as Falling Weight Deflectometer (FWD) provides crucial estimates of pavement health that assist in the optimisation of pavement management system.
Abstract: Applications of non-destructive testing devices such as Falling Weight Deflectometer (FWD) provide crucial estimates of pavement health that assist in the optimisation of pavement management system...
29 citations
Cites background from "Benchmarking the structural conditi..."
...Surface distresses, and visual condition ratings were also reported to affect deflection parameters, but no analytical or mathematical model was presented to determine the relation (Horak, 2008; Horak et al., 2015)....
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...…proposed DBP include surface curvature index, base curvature index, area under pavement profile, base damage index, base layer index, middle layer index, and lower layer index (Horak, 1987; Horak, 2008; Horak et al., 2015; Kim, 2000; Losa et al., 2008; Park et al., 2005; Xu et al., 2002a, 2002b)....
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TL;DR: In this paper , the authors used a falling weight deflectometer (FWD) test for evaluating the structural condition of conventional pavements through pavement deflection basin parameters (DBPs), which can provide a quick and comprehensive assessment for each layer in the inverted pavement structure without knowing the detailed properties of the layers.
Abstract: Inverted pavement has been a potential alternative to the conventional flexible pavement structure due to its cost-efficient usage of asphalt, comparable performance and durability. For increasing utilization of the inverted pavements, appropriate structural evaluation is necessary. The Falling Weight Deflectometer (FWD) test has been widely accepted for evaluating the structural condition of conventional pavements through pavement deflection basin parameters (DBPs). As a special type of pavement, inverted pavement relies on the stress-dependence of the unbound stone interlayer to withstand the heavy traffic loads, which typically affects a relatively larger pavement area. So far, there have been few systematic studies on the effectiveness of utilizing FWD to evaluate the structural conditions of inverted pavements. This study used a DBPs-based inverted pavement structure assessment system to assess an inverted pavement constructed in Georgia, USA. A nonlinear stress-dependent finite element model of the inverted pavement coupled with the impulse loading mode was built to simulate the realistic FWD loading process and investigate the effect of layer stiffness on the DBPs evaluation system. Furthermore, a full-scale inverted pavement section in Knoxville, TN, USA, was tested by the FWD method to obtain the corresponding deflection basin parameters. The DBPs data were used to evaluate this practical inverted pavement project based on the aforementioned DBPs-based assessment system. The analysis results show that the DBPs-based pavement evaluation method can provide a quick and comprehensive assessment for each layer in the inverted pavement structure without knowing the detailed properties of the layers. The evaluation results were consistent with the data from the testing vehicle equipped with the laser crack measurement system. Thus, the DBPs-based evaluation system is a promising method to assess the condition of the inverted pavement structures, contributing to the Inverted Pavement Management System (IPMS).
28 citations
TL;DR: The adequacy of DBPs to assess the structural condition of individual pavement layers was first assessed through Finite-Element Modelling, and DBPs were established as adequate alternatives for making network-level pavement assessment decisions.
Abstract: Decisions regarding the selection and implementation of appropriate pavement rehabilitation methods is usually based on pavement functional and structural condition data. Visual distress surveys an...
27 citations