Investigating the fatigue performance of grouted macadams

A conventional Grouted Macadam (GM) is manufactured by producing a highly porous asphalt skeleton, (25–35% voids), and filling the voids with a selected highly flowable cementitious grout. GM combines some of the best qualities of concrete and asphalt pavements, i.e. the flexibility and absence of joints which characterise asphalt and the high static bearing capacity and wear resistance of concrete. Moreover GM layers are impermeable and efficiently distribute the stresses in the underlying base layer. The speed of construction of GM surfacings and the short duration required prior to opening to traffic is a major advantage over conventional concrete. Current fields of applications include: airport pavements, industrial floors, harbours, bus terminals, distribution centres, and other heavily stressed areas. The aim of this investigation was to assess the fatigue behaviour of a range of GM mixtures. Indirect tensile fatigue tests and two point bending tests were conducted on laboratory manufactured specimens and on samples extracted from a trafficked pavement test facility. The experimental work provided interesting data on the influence of mixture composition on fatigue life and highlighted differences between strain and stress controlled fatigue tests on performance of GM mixtures compared with conventional asphalts.