Thermal Considerations for Roller-Compacted Concrete
Stephen B. Tatro and Ernest K. Schrader
Appears on pages(s):
adiabatic conditions; computer programs; cooling; concrete dams;cracking (fracturing); finite element method; gravity dams; roller-compactedt;concrete; stresses; temperature rise (in concrete); thermal properties.
The Willow Creek Dam near Heppner, Oregon, is the first dam constructed in the United States using the roller-compacted concrete (RCC) method and materials. Although the material is placed much like an earthfill, it must be considered to be mass concrete. Adequate design and control of the project depend on thermal studies to determine the internally-generated mass concrete temperatures and the resulting cracking potentiaI of the structure. A mathematical model can be formulated which, when incorporated with a finite element computer program, can accurately predict internal temperatures through-out the structure. Modifications to the method of inputting data to the computer program are necessary to accommodate the different properties and methods of RCC construction as compared to conventional mass concrete construction. A more detailed model of environmental temperatures is necessary because of the continuous RCC placement method. Detailed construction schedules must be developed to determine the quantity, sequence, and rate of RCC placement, and the program control must be altered to account for the smaller RCC lifts and the accelerated placement schedule. Temperature profiles for different zones of the structure can be plotted to indicate areas needing critical thermal control. Model variables, which are adjusted to minimize cracking potential, become contract requirements for the actual RCC placement.