This USACE project constructed an entirely new maintenance and operations facility for a heavy (armored) brigade being re-deployed to Ft Carson from Afghanistan. It included the construction of six Roller Compacted Concrete (RCC) hardstands and 1.75 miles of RCC tank trail. IHC placed over 212,000 square yards of 10" RCC pavement on the hardstands and tank trail. IHC also placed a substantial amount of concrete in the form of 23,700 lineal feet of curb and gutter in the personal vehicle parking lots, 9,100 square yards of sidewalks and 12 sets of stairways servicing the many buildings.
Schedule & Complexity
This 220,000 SY RCC Project had to be complete and ready by early 2009 to receive the troops being transferred to Fort Carson. Daily coordination between our RCC placement operations, other Site-work Contractors, and the Building Contractor was necessary to ensure that all parties had access to needed work areas at all times. The RCC hardstand pavement area was doubled in size and scope midway through the 2008 season with no increase in allowed time to complete. The RCC hardstands were completely surrounded by many of the maintenance buildings making it necessary to construct each of the six hardstand pavements in multiple phases thus providing continuous access to the buildings. IHC placed RCC on as many as 3 different hardstands within a day's placement operation to meet the project schedule.
After completion of the hardstand pavements, IHC constructed the 2 mile long RCC Tank Trail providing access to the six hardstand and maintenance building locations. Many concurrent construction projects were underway at Fort Carson including the reconstruction at the entry posts to the base creating delays to materials being delivered. Proper scheduling and coordination of the large material deliveries needed for RCC production were implemented to eliminate impacts to the project and ensure early completion.
Construction & Innovation
RCC Pavement had never been placed at Ft Carson prior to this project. Roller Compacted Concrete is a zero slump concrete pavement that is placed in a non-plastic state and consolidated into place with high density double tamper bar pavers and vibratory flat rollers. This results in a pavement that has performance qualities similar to conventional Portland Cement Concrete Pavement (PCCP) but at a lower cost. A new, state-of-the-art, Rapid-Mix Pug Mill was used to produce the mix. Placement of the RCC was accomplished with a high-density ABG 8820 paver. Consolidation rolling was performed using a combination of breakdown and surface finishing rollers in order to achieve the required density and surface finish. All specified quality was met and required schedule milestones were accomplished.
The flexural strength of the RCC was specified as 550 psi at 28 days. This was monitored with correlated compressive strengths from cylinders with confirming production beam breaks. Cores were also taken and broken according to ASTM procedures. All production strengths were met and no penalties were assessed. No incentives or bonuses were provided by this contract.
Meetings were held with the Corps of Engineers near the project's end to record the many lessons learned with this formerly untried product at Ft Carson. Specification changes were developed for future work including this technology. Overall, the use of RCC is seen as having valuable potential for future projects where an economic durable surface is needed.