REVIEW OF FALLING WEIGHT DEFLECTOMETER FOR ASSESSMENT OF FLEXIBLE PAVEMENT (original) (raw)
Related papers
Transportation Research Record, 2003
A direct and simple method (YONAPAVE) for evaluating the structural needs of flexible pavements is presented. It is based on the interpretation of measured FWD deflection basins using mechanistic and practical approaches. YONAPAVE estimates the effective Structural Number (SN) and the equivalent subgrade modulus independently of the pavement or layer thicknesses. Thus, there is no need to perform boreholes which are expensive, time consuming and disruptive to traffic. Knowledge of the effective SN and the subgrade modulus, together with an estimate of the traffic demand, allows for the determination of the overlay required to accommodate future needs. YONAPAVE simple equations can be solved using a pocket calculator, making it suitable for rapid estimates in the field. The simplicity of the method, and its independency of major computer programs, makes YONAPAVE suitable for estimating the structural needs of a road network using FWD data collected on a routine or periodic basis along the network roads. With increasing experience and confidence, YONAPAVE can be used as the basis for NDT structural evaluation and overlay design at the project level.
A benchmark analysis methodology utilising the imbedded structural response knowledge of the whole deflection bowl measured with the Falling Weight Deflectometer (FWD) was developed for comparative evaluation of the structural condition of flexible pavement structures. Zones in the pavement structure are associated with structural condition via correlations with various slope parameters on the measured deflection bowl determined from simple spreadsheet calculations. Deflection bowl parameter benchmarking has found application at network level analysis with FWD data by a number of road authorities world-wide. A number of additional area parameters based on various areas under the deflection bowl have recently been added, These additional deflection bowl parameters were evaluated and found to strengthen the established pavement benchmark structural analyses as a preliminary evaluation tool. More recently it was illustrated that structural condition indices such as the internationally ...
Most of the road network in India has a significant level of deterioration and therefore requires major rehabilitation projects; in general, most of these rehabilitation activities involve a new asphalt layer on the original pavement structure; knowledge and analysis of structural capacity of the pavement is essential to perform a durable and economical rehabilitation design. The determination of the structural capacity of flexible pavements as a function of the deflections produced by the application of a load. The techniques most used in many countries to measure pavement deflections are the Falling Weight Deflectometer (FWD) and the Benkelman beam, the first one works under dynamic loading and the second device under static loading. The use of devices under static loading has not been recommended by several design methodologies, including AASHTO, but these are still used widely in many countries including India, for this reason it is necessary to compare the deflections by Benkelman beam and falling weight deflectmeter. In this study deflections measure by BBD and FWD techniques on 30 deflection observation points on selected 1.5 km flexible urban highway stretch. Both test are perform simultaneously on marking points. And data collected by booth test are as per IRC: 81-1997 and IRC: 115-2014.
International Journal For Science Technology And Engineering, 2017
Most of the road network in India has a significant level of deterioration and therefore requires major rehabilitation projects; in general, most of these rehabilitation activities involve a new asphalt layer on the original pavement structure; knowledge and analysis of structural capacity of the pavement is essential to perform a durable and economical rehabilitation design. The determination of the structural capacity of flexible pavements as a function of the deflections produced by the application of a load. The techniques most used in many countries to measure pavement deflections are the Falling Weight Deflectometer (FWD) and the Benkelman beam, the first one works under dynamic loading and the second device under static loading. The use of devices under static loading has not been recommended by several design methodologies, including AASHTO, but these are still used widely in many countries including India, for this reason it is necessary to compare the deflections by Benkelman beam and falling weight deflectmeter. In this study deflections measure by BBD and FWD techniques on 30 deflection observation points on selected 1.5 km flexible urban highway stretch. Both test are perform simultaneously on marking points. And data collected by booth test are as per IRC: 81-1997 and IRC: 115-2014.
Deterioration Pattern of Flexible Pavement with the Help of Falling Weight Deflectometer
International Journal of Innovative Technology and Exploring Engineering (IJITEE, 2020
Maintenance and repair of the highway network system are major expenses in the state budget. For this reason, various concerned organizations are pointing out the need for developing an intelligent and efficient pavement performance model that can prioritize pavement maintenance and rehabilitation works. Such models can forecast the remaining pavement service life and pavement rehabilitation needs, and can help in the formulation of pavement maintenance and strengthening programmes which will reduce the road agency and road user costs. The flexible pavement performance or deterioration models involve the complex interaction between vehicles, environment, structure and surface of the pavement. Performance models relating to the pavement distress conditions like, cracking, ravelling, potholing, and roughness are analysed and developed by various researchers. Understanding the deterioration pattern of the flexible pavement is very important in order to take the decision for strengthening the pavement. The remaining life of the pavement depends on various factors such as Traffic, Environment and climatic conditions hence keeping in mind these factors. the thesis presents the pattern of the deterioration of remaining life of pavement. The thesis emphasis on determining the remaining life of pavement by conducting the FWD test. The FWD test is conducted on the same pavement for three time at regular interval to verify the remaining life of the flexible pavement.
Benchmarking the structural condition of flexible pavements with deflection bowl parameters
2008
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 streng...
2012
The paper describes a procedure where the condition of flexible pavements is investigated with the help of non-destructive tests such as the Falling Weight Deflectometer (FWD). The condition or indication of structural strength is expressed in terms of the Structural Number (SN). An existing method of determining the Structural Number was used as benchmark with data from a recent detailed pavement investigation. The benchmark SN determination also makes use of the Dynamic Cone Penetrometer (DCP) method. Previously only limited aspects of the measured deflection bowl were used to determine SN non-destructively. In this improved procedure additional deflection bowl parameters were investigated for their possible improvement in the determination of the SN or PN. The proposed method was therefore benchmarked against existing methods to determine SN for a pavement to see if it can lead to an improvement in determining SN values.
FALLING WEIGHT DEFLECTOMETER BOWL PARAMETERS AS ANALYSIS TOOL FOR PAVEMENT STRUCTURAL EVALUATIONS
The falling weight deflectometer (FWD) is used world wide as a well established and valuable non-destructive road testing device for pavement structural analyses. The FWD is used mostly for rehabilitation design investigations and for pavement management system (PMS) monitoring on a network basis. On project level investigations, both design charts and mechanistic approaches using multi-layered linear elastic theory and back-calculation procedures are often used to provide structural evaluations and rehabilitation options. As an alternative to this a semi-mechanistic semi-empirical analysis technique has been developed in South Africa whereby new deflection bowl parameters measured with the FWD used to give guidance on individual layer strengths and pinpoint rehabilitation needs. This approach is fully suited to supplementary analysis of FWD data in the Australian design systems, and overcomes some of the limitations of the curvature parameter. This paper briefly describes the current practice and basis of this use of deflection bowl parameters, and illustrates the use with a current pavement rehabilitation project underway in South Africa.