Washburn County (Wis.) Highway Department Commissioner Jon Johnson, P.E., oversees 200 miles of paved roads and offers guidance to area townships. Each year a number of these roads come closer to the end of their life cycle—a common situation nationwide, and in the state of Wisconsin, with the majority of the roads having a paved surface.
“Pavement management planning is important. When pavement reaches the point where overlaying is not the best choice, due to poor surface structure, poor or deteriorated base materials or simply insufficient base material to support traffic, full depth reclamation (FDR) has proven to be an excellent strategy,” stated Johnson. “Height limitations also tilt the decision toward FDR, allowing us to upgrade load strength without gaining height.”
In a neighboring state, the Minnesota Department of Transportation Local Road Research Board (LRRB) in 2013 concluded a three-year study to determine the granular equivalency (GE) values for stabilized FDR (SFDR) and unstabilized FDR bases. The results showed SFDR outperformed FDR. A GE of 1 in. for FDR material increased to a GE of 1.5 in. for SFDR material, providing 50% more carrying capacity to the existing material at a minimal cost.
Johnson continued, “Washburn County Trunk Highway B serves as a major collector and was last surfaced in 1976. A full reconstruction of the roadway would involve reconstruction to a Design Class C2 standard and was not financially feasible. The decision was made to perform a full depth reclaim (FDR) to pulverize the existing 3 in. of existing pavement and 4 in. of existing base, and to incorporate Team Laboratory Chemical Corp.'s BASE ONE base stabilizer. The BASE ONE and water mix was injected to a depth of 5 in. using the county-owned Wirtgen model 2000 XL. A 3.75-in. surface was applied in two lifts to finish the project. Owning our own reclaimer gives us the flexibility to schedule projects on our timetable."
"We were very happy with the 2012 SFDR project that the county performed," Johnson concluded. “We wanted to inject strength, and the BASE ONE provided good strength. We also had over 9 in. of rain during the construction of this May project.”
“To reconstruct this 3-mile segment it would have cost the county an estimated $2,700,000, and using the SFDR process with the BASE ONE product, we completed the project for $703,927, saving the county $1,996,073. We know that our future will include many more SFDR projects and we are ready.”