The Application of Microsurfacing in Repairing Pavement Surface Rutting

Rutting is one of the pavement distresses that mainly occur as a result of excessive loading on roads and it can cause roughness on the surface of pavements. The accumulation of water in rutted areas at rainy conditions results in reduced skid resistance, creating accident risk conditions for road users. One of the rapid and cost effective practices in filling ruts is using Microsurfacing mixes. Microsurfacing is a road maintenance tool that consists of laying a mixture of dense-graded bitumen emulsion mix, water, polymer additive, and mineral filler to correct deficiencies of pavement surfaces. In this research, a rather coarse size microsurfacing mix was designed and tested under load wheel, cohesiometer and wet track abrasion tests. The content of bitumen binders varies from 6.3 to 10% (i.e. percentage of the remained bitumen) and various amounts of latex was applied, ranging from 3 to 5%. Based on the above testing results it was revealed that microsurfacing mixes containing latex provided enhanced mechanical properties in the field. In addition, it was shown that among the above mentioned testing methods, abrasion and rutting tests were the most promising ones. The addition of latex modified binders resulted in improving characteristics of surface treatment mixes. In summary, it was resulted that the addition of 5% latex to emulsion mix containing 8.2% residual bitumen resulted in optimum conditions. With this formulation the mix showed almost 50% increase in both abrasion resistance and wheel load rut testing.