Application of GPR and FWD in Assessing Pavement Bearing Capacity

Abstract

The process of pavement maintenance and rehabilitation starts by collecting the data which will form the base for evaluation of pavement functional and structural condition. Collection of data can be performed by destructive and non-destructive testing. Usually preferred are the non-destructive methods, that do not damage the pavement, and the process of pavement evaluation is objective and repeatable. Non-destructive testing methods are becoming more and more popular, especially for assessing the structural condition of the pavement. Non-destructive testing by a Falling Weight Deflectometer (FWD) and the analysis of so collected data by the process of backcalculations is today the usual tool for assessing pavement bearing capacity. One of the basic input parameters for analysis of the data collected by FWD is pavement layers thickness.The practice in Croatia is to determine pavement layers thickness by coring. This destructive method affects pavement integrity, so the number of such tests should be kept to the minimum. By coring the accurate thickness of all pavement layers is obtained on specific point locations. Thus, numerous deviations in layer thickness remain unnoticed, and in the end, use of such data for the process of backcalculations does not provide ac urate values of layer moduli. Coring can be replaced with non-destructive method of testing by Ground Penetrating Radar (GPR), which provides continuous information on thickness of all pavement layers.The paper shows the method for assessing the bearing capacity of the pavement based on the data collected by FWD, GPR and coring. The calculation for layer moduli was performed by the ELMOD software, separately for the layers thickness data obtained by coring, and separately for the thickness obtained by GPR tests. Analysis and comparison of the results of calculated elasticity moduli obtained by using various methods for collecting layer thickness data were performed in the paper.

Future Trends in Transport Infrastructure Monitoring

“…This process also enabled calculation of the quantity of each material removed and overlaid and also, when available, calculation of the cost of these materials. Another application is aimed at modelling structural characteristics of the pavement measured through load tests with a Falling Weight Deflectometer [2], [10]. Two parameters were modelled; the central deflection D1 (Figure 10) that reflects general structural condition of the pavement, and the farther deflection D7, located at 1.8 m from the centre of the load plate, which reflects the stiffness of the subgrade.…”

Applications of GPR in Association with Other Non-destructive Testing Methods in Surveying of Transport Infrastructures

“…Sybilski et al (2012) present a case study of premature cracking where combination of GPR with FWD methods and laboratory measurements allowed the identification of severe water content as the reason for cracking. Domitrović and Rukavina (2013) deal with the comparison of pavement layer moduli calculated from FWD deflection data using layer thickness obtained by GPR and coring. Furthermore, this paper concluded that there is a tendency in reinforcement projects to apply recycling methods and use recycled materials so, knowing the continuous thickness of asphalt layers by GPR is essential in order to determine the optimum thickness available for milling and thus achieve optimization of recycling process.…”

Transport infrastructures assessment using multiple GPR configurations and FWD

“…FWD is considered the most effective NDT device for pavement deflection measurements worldwide [1][2][3]. It simulates the pavement responses under traffic loading [4] by applying an impulse load and measuring the pavement deflection bowl (see Figure 1).…”