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.
. J. WENZLICK, T. SCULLONO, K.R. MASER: “High Accuracy Pavement Thickness Measurement Using Ground Penetrating Radar”, Missouri Department of Transportation Research, Development and Technology Division, February 1999.
. M.OŽBOLT, T. RUKAVINA, J.DOMITROVIĆ: “Comparison of pavement layer thickness measured by GPR and conventional methods”, The Baltic Journal of Road and Bridge engineering, vol.7, no.1, 2012.
. T. SATTENKETO: “Timo, Electrical properties of road materials and subgrade soils and the use of Ground Penetrating Radar in traffic infrastructure surveys”, Faculty of Science, Department of Geosciences, University of Oulu, Finland, 2006.
. S. FONTUL: “Structural Evaluation of Flexible Pavements Using Non-Destructive Tests”, PhD thesis, LNEC, Lisabon, Portugal, 2004.
. F.ZHOU, T. SCULLION: “Guidelines for evaluation of existing pavements for HMA overlay”, Report 0-5123-2, Texas Transportation Institute, Texas, November 2006.
. S. ALAVI, J.F. LECATES, M.P. TAVARES: “Falling Weight Deflectometer Usage, A Synthesis of Highway Practice”, NCHRP Synthesis 381, Sierra Transportation Engineers, Inc.Reno, Nevada, 2008.
. “Use of Falling Weight Deflectometers in Pavement Evaluation”, COST 336, European Commission, Directorate General Transport, April 2005.