Title: Freeze-Thaw Durability and Deicer Salt Scaling Resistance of Roller-Compacted Concrete Pavements

Author(s): J. Marchand,M. Pigeon, H. L. Isabelle, and J. Boisvert

Publication: Symposium Paper

Volume: 122

Issue:

Appears on pages(s): 217-236

Keywords: aggregate gradation; air entrainment; compacting; deicers; freeze-thaw durability; pavements; roller-compacted concrete; saturation; scaling; Materials Research

DOI: 10.14359/2504

Date: 6/1/1990

Abstract:
Twenty roller-compacted concrete loads were cast at St. Constant near Montreal during the fall of 1987. Three types of cement (Canadian Types 10, 30, and 10SF), four different aggregate gradings, and three water-cement ratios (0:27, 0:33, and 0:35) were used to prepare the various mixes. Most of these mixes contained an air-entraining admixture. Approximately one-third of each concrete surface was moist-cured for 7 days, another third was covered with a white curing compound, and the remaining portion was not cured at all. Samples representative of all mixes and all curing conditions were taken from the pavement after 28 days and then tested for freeze-thaw durability (ASTM C 666) and deicer salt scaling resistance (ASTM C 672). The characteristics of the air-void system of all concretes were determined in accordance with ASTM C 457. With no exception, all samples withstood, without any significant deterioration, 300 cycles of freezing and thawing in water. However, the loss of mass after 50 cycles in the presence of a deicer salt solution ranged between 2 and 18 kg/mý (i.e., higher than the usual 1 kg/mý limit in all cases), even if most of the spacing factor values were below 250 æm. The best results (a weight loss of approximately 2 kg/mý after 50 cycles) were obtained for a mix containing Type 10 cement and no air-entraining admixture. In addition, this mix was not cured at all. Overwoking of the concrete surface during compaction is considered to be one of the possible explanations for the discrepancy between the results of the C 666 and the C 672 tests. It is also possible that the relationship between spacing factor and freeze-thaw durability does not apply to such concretes with a high permeability, numerous irregularly shaped compaction air voids, and large porous zones in the paste. This series of tests is the first phase of a 3-year research project on roller-compacted concrete pavements at Laval University, in collaboration with Canada Cement Lafarge. In the second and third years of this project, various ways to improve the scaling resistance (mostly by micro structural changes) will be studied.