A mix design method has been developed for Emulsified Bitumen Macadam materials (EBMs) used in trench reinstatement operations as wearing and base course layers in flexible pavement constructions. The method considers the effect of mixing, compaction, curing, strength development and moisture sensitivity. The influence of polymer-modified emulsions on the stiffness and permanent deformation characteristics of the EBMs has been investigated. EVA and SBS copolymers have been incorporated into a conventional 100 pen emulsion at various levels in the investigation, and the resulting EBM properties were compared to the specifications advocated by the Highway Authorities and Utilities Committee (HAUC) to arrive at suitable mixes that are capable of performing adequately in service.

The conventional and selected modified EBMs were then used in a laboratory study to evaluate their fatigue behaviour, together with an equivalent hot-applied mix containing 200 penetration grade bitumen. Controlled stress three-point bending fatigue tests were conducted to arrive at strain/fatigue life relationships for the hot and cold-lay mixes. Linear elastic theory was then applied to evaluate the response of the materials to traffic loading in a typical flexible pavement model using BISAR-PC Program developed by Shell. The calculated strains were used to determine the life of the pavements with candidate mixes from the developed fatigue relationships. Structural equivalency factors for the cold-lay materials in conjunction with the hot-applied mixes were computed from the resulting fatigue lives. The fatigue analysis revealed that certain modified EBMs have the potential to perform equally to, or even better than, the equivalent hot-applied material.