# ESTIMATION OF IN SITU ELASTIC MODULI OF PAVEMENT STRUCTURAL LAYER WITH FALLING-WEIGHT-DEFLECTOMETER DEFLECTION BASION. SIXTH INTERNATIONAL CONFERENCE, STRUCTURAL DESIGN OF ASPHALT PAVEMENTS, VOLUME I, PROCEEDINGS, UNIVERSITY OF MICHIGAN, JULY 13-17, 1987, ANN ARBOR, MICHIGAN

This paper describes the estimation method of the elastic moduli of a subgrade (E3), a granular subbase (E2) and an asphalt bound layer (E1). In this study, SAS-BISAR system is fully utilized and the pavement is simplified into three-layer structure by using deflection data, i.e. D sub 0, D sub 300, D sub 750, (suffices denote distances in mm from the center of the loading plate), which are obtained by the testing device of FWD. SAS-BISAR system was accomplished by combining BISAR and Super Application System (SAS). BISAR is an elastic analysis method for multi-layer, and SAS is a statistical software, which was developed by SAS Institute in U.S.A. and has valuable functions for data management and drawing figures. First, we attempt to find the most appropriate deflection variables for estimating the elastic coefficient of each layer of the pavement. The relation between D sub 750 and (D sub 300 - D sub 750) is useful to estimate the value of E3. In a similar way, the relation between D sub 750 and (D sub 0 - D sub 300), and the deviation (D sub 0 - D sub 300) are required for the estimation of E2. It becomes possible to estimate the elastic modulus of the whole asphalt bound layer (E1) by using the relation between D sub 0 and E1. The elastic modulus of the whole asphalt bound layer, cited above, has a good agreement with the elastic modulus of the asphalt mixture which was obtained in the dynamic indirect tension test with a loading time of FWD. We propose the relatively simple estimating method of E2 and E3 with the known variable E1. In this method, a diagram of the relation between delta sub 750 and (delta sub 300 - delta 750) is drawn by the use of SAS-BISAR system. Plotting D sub 750 and (D sub 300 - D sub 750), values which are actually measured, on this figure, E2 and E3 are estimated by interpolation. By the use of this method E2 and E3 are estimated for various kinds of the asphalt pavement structure.

• Corporate Authors:

University of Michigan, Ann Arbor

Department of Civil Engineering
Ann Arbor, MI  United States  48109
• Authors:
• Kasahara, A
• Kubo, H
• Sugawara, T
• Publication Date: 1987

## Filing Info

• Accession Number: 00485626
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 31 1989 12:00AM