Fracture and fatigue strength of grouted macadams

Abstract

Grouted macadams form a class of material which provides significant advantages in comparison to both concrete and conventional asphalt, having both rut resistance and a degree of flexibility. This paper presents a series of laboratory tests on several grouted macadam mixtures, for stiffness, fatigue and low temperature fracture. The variables explored include binder grade and content, aggregate size and gradation, and grout strength. Although the material is found to perform fundamentally as an asphalt, there are several significant differences in the form of fatigue behavior found compared to that usually expected from an asphalt. In particular the effect of varying binder content is found to be markedly different. The results are discussed in terms of optimizing mixture design in order to obtain the most desirable combination of properties (stiffness, fatigue strength, low temperature fracture resistance). Discussion is also presented regarding the possible role of grouted macadams as base or binder courses within highway pavements, and the conclusion is drawn that they are likely to provide an economical solution in many circumstances owing to their superior mechanical properties.