The good performance of the waterbound macadam single-sized coarse aggregate base type in wet regions has revived Interest in this once labour intensive method of base construction. Specifications have been improved and guide-lines given for the mechanized construction of waterbound macadam bases. Density standards have been set for typical waterbound macadam bases following the construction of four experimental sections, the development of the Rondawel Density Test and accelerated testing with the Heavy Vehicle Simulator. The performance of these waterbound macadam bases Is compared with that of other high quality granular bases. Guide-lines are given for the determination of effective elastic moduli of typical waterbound macadam bases and the mechanistic analysis of such granular base pavements.
The response of prestressed concrete sleepers to torsional loading was investigated. A theoretical prediction of the ultimate torsional resistance moment of a type F4 prestressed concrete sleepers was given, using the space truss model for reinforced concrete beams under torsional loading. The results of an experimental investigation into the structural behaviour of prestressed concrete sleepers under torsional loading and a combination of torsional and flexural loading were also reported. Even with the required design flexural moment an adequate resistance to combined moment and torsion was obtained.