Granular shoulders need to be maintained on a regular basis because edge ruts and pot holes could possibly develop which could pose a safety hazard to vehicles. To stabilize shoulders and reduce the number of necessary maintenance cycles per season, one possible stabilizing agent - acidulated soybean oil soapstock (referred to as "soapstock") is investigated in this research. By the end of the study, researchers were able to determine whether and under what conditions this soapstock could be effective in mitigating edge rutting and pot holes for granular shoulders. In order to achieve this goal, a pilot testing project was conducted for selected problematic shoulders around northern and northeastern Iowa. Soapstock was applied on granular shoulders with monitoring during application and pre-and post-observations. In this thesis, application techniques were documented and percentage of application success was calculated for each treated shoulder section.

As a result of this research, it is concluded that Soybean oil soapstock can be an effective stabilizer for granular shoulders under certain conditions. The documented application techniques could be used as the basis for future guidance for applying soapstock or similar products on granular shoulders. In addition, recommendations are made for future research projects that could be conducted to study the effects and sensitivities of possible influence factors listed in this thesis.