Eugene’s award-winning, sustainable road-repair practices have become even more healthful, thanks to a new technique for constructing cement-treated road bases.
Eugene Public Works helped pioneer a process for recycling streets in place. In this process, the asphalt pavement is mixed with the road-base gravel and a few inches of soil using a 70,000-pound rototiller. A cement slurry is then applied over the blended material, rototilled a second time and compacted, creating a cement-treated base. In the past, the cement was added in a powder form, which was then watered, tilled and compacted to form the reinforced base. However, the use of cement powder often created “fugitive dust” that got on construction workers, equipment, and even on residents and their vehicles if they drove through the work zone before the cement was thoroughly worked into the base.
The new process, which is being used on repairs to Shasta Loop, Firland Boulevard and 43rd Avenue, eliminates the cement dust factor. The contractor, Knife River, mixes cement powder, sand and water, offsite, to create a thick cement slurry, which is transported in a cement-mixer truck and spread over the prepared subgrade. The slurry is then tilled in and compacted to form a cement-treated base as strong, or stronger, than the base formed using powdered mix.
City Public Works Engineering staff required the cement slurry process after researching road-building advancements in other states. Other sustainable road-repair practices in Eugene include the use of reclaimed asphalt paving and reclaimed asphalt shingles in asphalt mixes and the use of warm-mix asphalt, which saves on the energy needed to heat the asphalt and also reduces off-gassing of volatile organic compounds.
For more on this year’s in-place road recycling projects, contact project manager Kerry Werner at 541-682-5477.