Pilot Construction Project for Granular Shoulder Stabilization

2013Final ReportPDFTech ReportIHRB Project TR-634InTrans Project 11-405TR-63411-405Annual average daily trafficConstruction projectsDust controlGranular materialsMaintenanceRoad shouldersRuts (Pavements)HighwaysMaintenance and PreservationPavementsI30: MaterialsAggregate StabilizationEdge-rut MitigationGravel ShouldersShoulder maintenanceSoybean SoapstockStabilization EquipmentStabilizing AgentsUnited StatesIowaIowa State University. Institute for TransportationGuo, FangyuGuerra, Miguel AndresJahren, Charles T.White, David J.Iowa State University. Institute for TransportationIowa. Highway Research BoardIowa. Dept. of TransportationUS Transportation CollectionGranular shoulders need to be maintained on a regular basis because edge ruts and potholes develop, posing a safety hazard to motorists. The successful mitigation of edge-rut issues for granular shoulders would increase safety and reduce the number of procedures currently required to maintain granular shoulders in Iowa. In addition, better performance of granular shoulders reduces the urgency to pave granular shoulders. Delaying or permanently avoiding paving shoulders where possible allows more flexibility in making investments in the road network. To stabilize shoulders and reduce the number of maintenance cycles necessary per season, one possible stabilizing agent\u2014acidulated soybean oil soapstock\u2014was investigated in this research. A pilot testing project was conducted for selected problematic shoulders in northern and northeastern Iowa. Soapstock was applied on granular shoulders and monitored during application and pre- and postapplication. Application techniques were documented and the percentage of application success was calculated for each treated shoulder section. As a result of this research, it was concluded that soybean oil soapstock can be an effective stabilizer for granular shoulders under certain conditions. The researchers also developed draft specifications that could possibly be used to engage a contractor to perform the work using a maintenance-type construction contract. The documented application techniques from this project could be used as guidance for those who want to apply soapstock for stabilizing granular shoulders but might not be familiar with this technique