A study on the development of Microsurfacing surface performance under laboratory-scale traffic simulation

In the field of preventative maintenance techniques, microsurfacing has gained scientific and practical interest, especially because of its effectiveness in restoring several distresses on structurally sound pavements; moreover, it provides social, economic and environmental benefits since it is cold-applied in thin layers (less material and energy consumption), and it is fast-setting, allowing a quick reopening to traffic. Microsurfacings are also widely recognised for providing a regular and even surface texture with high skid resistance. Besides, assessing how the pavement surface performance changes over time under traffic conditions becomes essential in road pavement management. In light of the above and within the RILEM TC 280-CBE research activities framework, the work focused on optimising different bituminous cold microsurfacing mixtures: ‘Basalt 0/6’, ‘Basalt 0/8’, and ‘Granite 0/8’. The optimised mixtures were fully characterised and subjected to a laboratory traffic simulator’s action to study the development of the surface performance in terms of texture and skid resistance. A procedure has been implemented to model the relationship between the surface performance and the loading cycles, identifying the most representative phases (polishing and equilibrium) of the surface characteristics evolution. Notably, pertaining to skid resistance, the ‘Granite 0/8’ mixture achieves the same percentage decrease (about 18%) in a shorter conditioning period compared to the basalt ones. Regarding texture, the ‘Basalt 0/8’ mixture rapidly reaches the equilibrium phase but exhibits a lower drop (24.0%) compared to ‘Basalt 0/6’ and ‘Granite 0/8’ (38.0% and 39.6%, respectively).