EVALUATION OF TEST METHODS AND SELECTION OF AGGREGATE GRADING FOR TYPE III APPLICATION OF MICRO-SURFACING

Abstract

Micro-Surfacing is a polymer modified, binder emulsion based, dense graded, cold mixed, and quick setting, asphalt resurfacing material. Type III application of microsurfacing is used as the rut fill materials for highly trafficked roads. As of now, International Slurry Surfacing Association (ISSA) mix design guideline is the widely used standard to design micro-surfacing mixtures. The research described in this paper intended to suggest modifications to the actual ISSA mix design procedure to accurately select aggregate grading for type III micro-surfacing mixtures. To do this, a sensitivity analysis was performed in order to study the effect of aggregate gradation, and binder emulsion residue on five micro-surfacing mixture design tests, including Loaded wheel test (ISSA TB 109), Wet track abrasion test (ISSA TB 100), modified cohesion test (ISSA TB 139), vertical displacement test (ISS TB 109, Method-A), and Mixing time test (ISSA TB 113). The second part of study consisted mainly of establishing a limit for the aggregate gradation used in type III application of micro-surfacing, which gives higher resistance to rutting as it is the main property of type III micro-surfacing. In order to do this, the resistant of different micro-surfacing mixtures against rutting was evaluated, and modified specifications were suggested to select aggregate grading for type III microsurfacing.