Effect of steel slag aggregate and bitumen emulsion types on the performance of microsurfacing mixture

Microsurfacing has recently been accepted widely as an effective method for preventive maintenance of pavements. Microsurfacing is a mixture of cationic polymer-modified bitumen emulsion, 100% manufactured well-graded fine aggregate, mineral filler, water, and chemical additives. In this research, in order to evaluate the performance of steel slag in microsurfacing mixture, two types of bitumen emulsions (cationic quick setting and cationic slow setting) were used together with three types of mixtures in which 100% siliceous aggregate was used as a control mixture and then steel slag was replaced by 61% and 100% aggregate of control mixture. The performance of the samples was evaluated by experiments included wet cohesion test, wet track abrasion test, and loaded wheel test, according to international slurry surfacing association (ISSA) A143 guideline and ASTM D6372 standard. The results of tests showed that steel slag aggregate has proper compatibility with both of bitumen emulsion types judged by its desirable physical, chemical, and mechanical properties. The alkali characteristic of the steel slag leads to a stronger adhesion of these materials to acidic bitumen and cause prevented the stripping in the vicinity of water in comparison to the control mixture. Also, steel slag-containing mixtures displayed a more appropriate behavior in terms of rutting and stripping distresses.