High Volume Fly Ash RCC for Dams: Freezing and Thawing Durability

Abstract

The freezing and thawing durability of Norway's first Roller Compacted Concrete (RCC) dam was studied using the Scandinavian slab test (European/CEN test method for freezing and thawing durability) and ASTM C671 freezing dilation test. RCC with W/(C+FA) = 0.53 and FA/(C+FA) = 0.67 had some scaling and severe internal cracking in the wet freezing and thawing exposure of the slab test. The period of freezing and thawing immunity of RCC in the separated absorption and sealed freezing procedure of the dilation test was shorter than that of the conventional facing concrete (FC). Air entraining improved the RCC's freezing and thawing resistance, although not to be as good as that of FC with W/(C+FA) = 0.50 and FA/(C+FA) = 0 and 0.40. The FC had low scaling and no sign of internal cracking in the slab test, and the RCC's period of freezing and thawing immunity was longer than the 120 days of absorption used in the dilation test. The air voids of the RCC were coarser and the protective share of voids (= voids that are not filled by capillary suction but filled by 10 MPa pressure head) was lower than in the FC. Critical degrees of saturation were determined for service life prediction by combining dilation- and degree of saturation measurements.