Colorado D.O.T. – Central 70 Project
The Colorado DOT is using EdenCrete® in shotcrete for abutments and caissons as it widens 10-miles of the interstate and the roadways underneath its overpasses in the Central 70 project.
EdenCrete® was used to optimize the original, straight cement mix to pump more easily and to improve the strength. A lab program evaluated the specified mix versus a companion mix containing Class F fly ash and a small dosage of EdenCrete® in place of ~145 lbs of cement per cubic yard of concrete. The combination of fly ash and EdenCrete® improved the rheology of the mix so that it could be placed according to schedule. The mix having reduced cement content and EdenCrete® exceeded the overdesign required by ACI and the mix was stamped and specified for the 3-year project.
In Denver, CO, the Colorado Department of Transportation has begun the massive Central I-70 project to widen the interstate and the roadways underneath its overpasses. Shotcrete is being used to reinforce new/existing caissons and abutments supporting the many bridge spans to be expanded along the 10-mile stretch of I-70. The shotcrete mix needed to pump more easily in order to keep up with the placement schedule and was required to meet the specified design strength.
Concrete ProducerMetro-Mix Denver North
Location/DateDenver, CO | December 2018 start, 3-year project
ContractorThorcon Shot Crete and Shoring LLC
Volume & Dosage
Shotcrete Containing EdenCrete® at ¼ gal/yd3
Project Details and Conclusions
As the contractor began shooting the mix, he immediately commented on how well it was pumping. After a short conversation regarding improved rheology allowing for the use of lower pump pressure, the pump operator reduced the pump pressure from ~3900 psi to ~2700 psi. The mix began to pump and stack better at lower pressure than it did at higher pressure. Because the mix was now shooting against the wall with less force, dust and waste from rebound were also reduced. No water was added to the truck during pumping, helping to maintain the design strength of the concrete as it was produced at the plant. The nozzle operator commented that his shoes were clean, and this was not common. The mix did not segregate or pack sand in the line, eliminating the need to disconnect and clear hose lines. The contractor was very pleased with the EdenCrete® mix and it will continue to be used to support caissons and abutments along the Central 70 Project through 2021.
The project involves approximately 6000 yd 3 of shotcrete containing EdenCrete® at ¼ gal/yd. 3 and will take place over three years.