Comprehensive Investigation of Influential Mix-Design Factors on the Microsurfacing Mixture Performance

Abstract

This study aims to enhance the performance of the microsurfacing mixture and evaluate the parameters affecting this mixture. For these purposes, the effects of pure bitumen types for producing bitumen emulsion, types of aggregates, and the percentages of bitumen emulsion and emulsifier on the microsurfacing mixture are investigated. Three different types of pure bitumen with penetration grades of 40–50, 60–70, and 85–100 were used to make bitumen emulsion. In addition, limestone and siliceous aggregates, 0.9%, 1.2%, 1.5% emulsifier, and 9%, 10%, and 11% bitumen emulsion were used for test samples. The microsurfacing mixture was then evaluated by cohesion, wet track abrasion, loaded wheel, and mixing time tests. The results revealed that increasing the percentages of bitumen emulsion, emulsifier, limestone aggregates, and bitumen emulsion made from softer pure bitumen increased the microsurfacing mixture’s breaking time. Moreover, the test sample containing bitumen emulsion made from harder pure bitumen, limestone aggregates, and lower emulsifier percentages showed a better setting time, which is suitable for a quick traffic reopening system. In addition, using limestone aggregates, pure bitumen with a lower penetration grade and a higher emulsifier percentage declined the optimum bitumen emulsion percentage. It also enhanced the microsurfacing mixture’s resistance to abrasion, rutting, and moisture sensitivity. Overall, using limestone aggregates and bitumen emulsion made from harder pure bitumen improved the microsurfacing mixture performance, preventing some distresses, including rutting, stripping, bleeding, and aggregates’ polishing, which can lead to the longer service life of this mixture.