Use of FWD Deflection Basin Parameters (SCI, BDI, BCI) for Pavement Condition Assessment

Ott Talvik, Andrus Aavik


Current research studies relationship between Falling Weight Deflectometer (FWD) deflection basin parameters and road pavement structural condition indicators, such as fatigue cracking and permanent deformations induced by low bearing capacity of pavement, and pavement equivalent E modulus (Eeq). The primary aim of the research was to develop limit values for deflection basin parameters: surface curvature index (SCI), base damage index (BDI) and base curvature index (BCI). Analyses of data derived from the Estonian Road Databank disproved the hypothesis of relationship between deflection basin parameters and pavement defects or rutting. Deflection basin parameters and back-calculated Eeq were found to be in good correlation. Strong relationships were found between upper layers indicators (SCI and BDI) and Eeq. Relationship between subgrade indicator BCI and Eeq, found in the research, was not very strong. Based on the aforementioned relationships, and the required min equivalent modulus of particular pavement, the equations to determine the limit values of deflection basin parameters for different types of pavements were developed. As the statistical analyses of such extensive database have been done for the first time in Estonia, the determined limit values have to be evaluated in practice and, if needed, corrected.


FWD; deflection basin; surface curvature index (SCI); base damage index (BDI); base curvature index (BCI); limit value

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DOI: 10.3846/1822-427X.2009.4.196-202


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