Last spring, the city of Fairburn, Ga., needed to upgrade Virlyn B. Smith Road prior to the Georgia Renaissance Festival. The road sees an enormous amount of traffic during this sixweek festival, which recreates a 16th-century European country fair. Additionally, heavy truck traffic from residential building had distressed the 22-ft-wide road. Distresses along this 1-mile stretch included moderate to severe fatigue cracking, thermal cracking and potholes. The city needed to rebuild and widen this road within a critical one-month construction schedule.
The solution was Fortress Full Depth Reclamation (FDR). Fortress FDR consists of an engineered mix design, performance-related specifications and an innovative asphalt emulsion to produce a flexible base that is strong enough for traffic before surfacing and improves crack resistance and moisture susceptibility. The process interested the city due to the ease of construction, quick return of traffic and benefits of a flexible base, such as withstanding repeated traffic loadings and temperature fluctuations.
To achieve the design goal of widening the road to 26 ft and stabilizing 8 in. of base with asphalt emulsion, the Miller Group, the project contractor, trenched out 2 ft on each side of the road. Then they pre-pulverized 10.5 in. of hot-mix asphalt (HMA) and aggregate base with a Wirtgen 2500 road reclaimer , and the extra 2.5 in. were spread into the trenches using a motor grader. The road reclaimer made a second pass adding 4.5% emulsion, supplied from SemMaterials’ Garden City, Ga., plant, at a depth of 8 in.
To maintain traffic throughout the construction process, four passes with the reclaimer were required to stabilize the full width of the road.
The road was then compacted using a padfoot roller, and the motor grader smoothed the surface to grade. The next step was compacting the road with a pneumatic tire roller followed by a steel wheel roller. A week later, a 2.5-in. HMA binder course and a 1-in. wearing course were placed on the stabilized base. Less than two weeks later, without potholes or construction delays, the Georgia Renaissance Festival opened to approximately a quarter million visitors. The city was so pleased with the construction process they are already considering FDR on future projects.
The four-month data shows the strength has increased 1.5 to 3.5 times over the preconstruction data. Since the stabilized base will not fully cure for six months after construction,the strength will continue to improve.
The city’s alternative to FDR was patching 40% of the project with 6 in. of HMA at an estimated cost of $280,000. Fortress FDR saved the city $30,000 while treating the entire length of the project to a depth of 8 in.
