- Author
-
Snyder, K. A.
|
Clifton, J. R.
|
Knob, L. I.
- Title
- Freeze-Thaw Susceptibility of High Performance Concrete.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Book or Conf
- International Conference on Building Materials. Proceedings. September 22-24, 1994,
Weimar, Germany,
139-142 p.,
1994
- Keywords
-
building technology
|
concretes
|
freeze-thaw
|
high performance concrete
|
hydraulic pressure theory
|
spacing factor
- Abstract
- Based upon the physical arguments used by Powers to develop the hydraulic pressure theory for the air-entrainment requirement of concrete, it is reasonable to expect that low water-cement ratio concretes, under certain conditions, may not require air entrainment. Powers' critical spacing of the air voids is proportional to permeability and tensile strength, and inversely proportional to capillary porosity. At early ages the permeability of the paste is large and at later ages the tensile strength is large and the capillary porosity is small. Therefore, the critical spacing should become a minimum at intermediate ages. Results from freeze-thaw tests performed on concretes with water-cement (w/c) ratios of 0.28 and 0.38 with no air-entrainment dindicate an intermediate age when the concrete was most susceptible to freeze-thaw damage. An experiment has been performed in which samples were subjected to freeze-thaw cycling after 3, 7, 14, 28, 56, and 91 days of curing. The specimens of the w/c=0,38 concrete that were cured for 3, 7, 14, and 28 days failed the ASTM C 666 freeze-thaw procedure. Except for the 3-day specimens performing as well as the 56-day specimens. The existence of a pessimum hydration time for the 0.28-w/c concretes can be estimated qualitatively using a simple analysis based upon Powers' hydraulic pressure theory.