Concrete pavements have long been recognized for their longevity and low life cycle costs. A large number of concrete pavements constructed in the 1920s and 1930s in California are still in use today, serving communities for 70 to 80 years with little maintenance cost. The history of these pavements, including their exceptional longterm performance, has not been told and the story that they tell is being lost as many of these 80 to 90 year old historic concrete pavements are being rehabilitated with asphalt overlays or reconstructed.
Roller-compacted concrete, or RCC, takes its name from the construction method used to build it. It’s placed with conventional or high-density asphalt paving equipment, then compacted with rollers. RCC has the same basic ingredients as conventional concrete: cement, water, and aggregates, such as gravel or crushed stone.
Concrete pavement restoration, or CPR, is a series of engineered techniques developed over the past thirty years to manage the rate of pavement deterioration in concrete streets, highways, and airports. CPR is a non-overlay option used to repair isolated areas of distress in a concrete pavement without changing its grade. This rational, preventive procedure restores the pavement to a condition close to original and reduces the need for major and more costly repairs later. In fact, recent reports from the Transportation Research Board state that for every dollar invested in appropriately timed preventive pavement maintenance, three to four dollars in future rehabilitation costs are saved.
Concrete pavements have long been recognized as clean, smooth riding, strong, and durable, and properly designed and constructed concrete pavements should provide several decades of zero- to low-maintenance service. At times, it is necessary to cut trenches in some concrete pavements, particularly in urban areas, in order to repair or install utilities such as sewers, drainage structures, water mains, gas mains and service lines, telecommunication lines, and power conduits.
FDR-C uses less cement and water than conventional concrete and concrete base. The FDR-C unconfined compressive strengths are correspondingly less than these materials.
The FDR-C pavement rehabilitation process pulverizes and shapes the existing AC pavement and a portion of the underlying materials, and mixes the pulverized materials with cement and water, usually in a separate operation. The processed mixture is then graded, compacted, and surfaced.
Full-depth reclamation (FDR) recycles the materials from deteriorated asphalt pavement, and, with the addition of cement, creates a new stabilized base. A surface consisting of a thin bituminous chip seal, hot-mix asphalt, or concrete completes the rebuilt road. The recycled base will be stronger, more uniform, and more moisture resistant than the original base, resulting in a long, low-maintenance life. And most important, recycling costs are normally 25% to 50% less than removal and replacement of the old pavement.
Full-Depth Reclamation (FDR) with cement is a procedure where failed asphalt pavements are pulverized and reclaimed, using cement to stabilize the recycled materials and create a new pavement base. This cementstabilized base is then surfaced to provide an new, long-lasting pavement structure.
This report summarizes the long-term performance of pavement construction projects where the FDR with cement process has been used. The actual field performance of more than 75 projects in eight states were evaluated. The average project age was 9 years, and the oldest was 26 years.
Roadbuilding and paving are no exception. That’s why engineers and public works officials are turning to a process called full-depth reclamation (FDR) with cement. This method rebuilds worn out asphalt pavements by recycling the existing roadway, reducing the raw materials and energy consumption.
The old asphalt and base materials are pulverized in place, mixed with cement and water, and compacted to produce a strong, durable base for either an asphalt or concrete surface. FDR uses the old asphalt and base material for the new roadway base. There’s no need to haul in aggregate or haul out old material for disposal. Truck traffic is greatly reduced, and there is little or no waste.
Deteriorating roads are a constant problem for cities and counties. That’s why engineers and public works officials are turning to a process called full-depth reclamation (FDR) with cement. This process rebuilds worn out asphalt pavements by recycling the existing roadway.
When asphalt pavements fail. determining the best rehabilitation procedure can be difficult. A simple asphalt overlay or a “mill and fill” approach can improve the appearance of the pavement surface, but may do little to correct the underlying problems that caused the failure in the first place. Within a short period of time the problems will likely reappear.
Long-term solutions to failed asphalt pavements include a thick structural overlay or complete removal and replacement of the existing base and asphalt
surface. Both methods can be very expensive and wasteful of virgin aggregates.