CHAPTER 9
CONCLUSIONS AND RECOMMENDATIONS
9.1 Conclusions
A research study was conducted to evaluate NDT deflection response
of flexible pavements and to develop procedures for the prediction of
layer moduli. The investigation included analyses of both computer-
simulated and field-measured NDT data on fifteen flexible pavement
sections in the state of Florida. In situ cone penetration, Marchetti
dilatometer and plate bearing tests were performed on most of these
pavement sections. The following conclusions were derived from the
results obtained in this investigation:
1. A simplified approach which allows a layer-by-layer analysis of the
Dynaflect deflection basin has been developed. This technique,
which utilizes a modified Dynaflect geophone configuration (Figure
F.l), provides the capability to separate the deflection response
contributed by the subgrade, stabilized subgrade, and the combina
tion of base and asphalt concrete layers for typical Florida flexi
ble pavement systems.
2. Analyses of Dynaflect data from the fifteen in-service flexible
pavements using the BISAR elastic layer computer program resulted in
the development of simple power law regression equations to predict
layer moduli from modified sensor deflections. A recommended test
ing and analysis procedures using the modified Dynaflect testing
system has been presented in Appendix F. The computational
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