The Folsom Dam Auxiliary Spillway project, a $900-million cooperative effort between the U.S. Army Corps of Engineers and the U.S. Department of the Interior's Bureau of Reclamation, began in 2012. The new spillway was constructed to safely release water from Folsom Lake when water levels are elevated to protect communities during a flood.
Granite Construction of Watsonville, Calif., was awarded a $125.9-million contract in May 2012 to build the spillway during phase three. Kiewit Infrastructure West was awarded a $255.1-million contract in May 2013 to complete construction during phase four.
The spillway includes an 1,100-ft. (335m) approach channel that will funnel water from the lake into the spillway. A control structure with six submerged gates was constructed to operate in coordination with the gates on the dam to control water releases. A 3,027-ft. (923m) spillway chute transports water from the control structure to the American River. A stilling basin slows the flow of released water to normal flow levels that the river channel can safely withstand.
The control structure is the central component used to prevent dam failure and risk of flooding. To ensure its long-term performance, a Komponent® expansive cement admixture designed to create shrinkage-compensating grout was specified for use around the curved, stainless steel gate supports. This critical application area requires long-term dimensional stability of the grout to ensure the gates open and close properly. Shrinkage and cracking of the cementitious grout would prevent the gates from closing properly and leave gaps that leak. Over time, the resulting volume change and movement would increase leakage points and ultimately accelerate deterioration - and potential failure - of the control structure.
Komponent expansive cement additive was chosen due to its proven performance in shrinkage-compensating concrete and non-shrink grout designs. Komponent is engineered to achieve a net-zero drying shrinkage, prevent drying shrinkage cracking, and ensure long-term dimensional stability.
For this project, Komponent was used at a 16% dosage rate, which replaced 16% of the total portland cement content in the original mix design. Fly ash was also used in this high-performance mix design. The dosage rate was determined based on ASTM C806 and C878 testing to ensure designed expansion was achieved. The dosage rate is evaluated to ensure it provides sufficient expansion to compensate for the anticipated shrinkage of the portland cement in the mix.
Due to site conditions and construction concerns, ready-mix delivery of the grout was not viable. Jobsite batching was required. To meet these project requirements, the Komponent additive was provided in 90-lb. bags and introduced into the mix using a high-velocity slurry mixer. The shrinkage-compensating grout was then pumped into the stainless steel gate supports and finished.
The Komponent non-shrink grout achieved the 7000-psi design requirement and the designed shrinkage-compensating expansion. Gate installations were completed successfully. Two years after installation, Project Engineer Jared Thornton noted that the Komponent non-shrink grout is meeting design expectations.
The communities serviced and protected by the Folsom Dam Auxiliary Spillway Control Structure can enjoy peace of mind on a job well done by the entire project team.
For information on how Komponent® can be used to provide a high-performance shrinkage-compensating concreting or grouting solution on your next project, contact a member of the CTS Cement Engineering Team at (800) 929-3030 or info@CTScement.com.