Abstract
M.Ing. (Civil Engineering)
The: structural classification of granular base pavements by means of resilient deflection bowl
parameters measured by the Impulse Deflection Meter and application of measured deflections at
network level were investigated. The Investigation consisted of a mechanistic analysis and an analysis
of observed field results. Curves for structural classification of granular base pavements obtained by
regression are presented. The Curves obtained by the analysis of field observations compare well with
local experience and theoretical failure criteria. It was found that the mechanistic model used in this
study did not yield satisfactory results when simulating deflection behaviour through linear elastic
programs. The parameters recommended for future use are Maximum Deflection (Y-rnax), Base
Layer Index, or DLl (formerly SCI), Middle Layer Index, or MLl (formerly DOl) and Radius of
Curvature. The use of deflection measurements at network level was also investigated. A method
for calculating a Structural Stiffness Index to be incorporated into Pavement Management Systems
as a Structural Indicator is proposed. Recommendations regarding the density of testing and
identification of roads for testing at network level are also made. Several factors influencing
deflections and structural bearing capacity are discussed and some recommendation." are made. The
main factors influencing deflections and predicted pavement structural capacity were shown to be
Temperature, Seasonal Influences and Condition of Surfacing. Further research into the specific
influence of these factors on deflections and hearing capacity is needed.