Civil Engineering Association

Subgrade Stabilization ME Properties Evaluation and Implementation

The state and many counties throughout Minnesota are using a variety of subgrade stabilization techniques for various materials used in road construction. Such methods appear to improve constructability and lead to increased performance and reduced maintenance. While a number of studies have investigated such stabilization efforts (including materials and techniques, relative increases in strength and/or stiffness, etc.) no overall quantification and summary of the effects of material stabilization have been brought forward with recommendations of parameters to be used for design purposes. Although these techniques and materials are commonly used, minimal information has been obtained relating to the Mechanistic-Empirical (ME) properties of these improved materials such that the more cost-effective designs can be implemented. Not having recommendations for the ME properties of the improved materials, the designer is forced to use values for the non-stabilized material. While this does likely lead to extended road life, costs could be greatly reduced by taking advantage of the improved properties of the stabilized roadway materials. This project has involved determining which types of subgrade stabilization are being used, identifying which of these stabilization techniques/materials are of interest to the Minnesota Department of Transportation (MnDOT), compiling the results of past research relating to these stabilization techniques, summarizing the results of past research and proposing a mix design procedure that obtains material properties for use in design. This proposed mix design procedure will allow the designer to account for improved stiffness due to stabilization, reducing costs and improving the efficiency of the design.