The South African mechanistic rehabilitation design procedure is well established and has been verified with the help of a fleet of heavy vehicle simulators. Surface deflection basins can be measured with the road surface deflectometer or the National Institute for Transport and Road Research deflectograph. Typical South African pavement structures were analysed, and various deflection basin parameters were calculated. The equivalent-layer-thickness (ELT) concept was investigated for its applicability to this analysis procedure and was found to be useful in representing the structural capacity of a pavement. The basis for the calculation of the ELT is the effective elastic modulus of the subgrade. Deflection points measured on the extremes of the deflection basin are used to calculate the subgrade effective elastic modulus. Various deflection basin parameters can be used to calculate pavement ELT, which can be related to typical distress determinants or directly to remaining life in a design-curve approach.
Samenvatting