IDENTIFICATION OF FROST SUSCEPTIBLE AGGREGATES AND THEIR USE IN CONCRETE OR BITUMINOUS PAVEMENTS

Coarse aggregates have been recognized as potential sources of deterioration of concrete exposed to freezing and thawing action. Whenever coarse aggregates are involved, deterioration of pavement structures can take place as pitting, pop-outs, and varying extents of D-cracking. Recently, serious damage of bituminous pavements was observed where the coarse aggregate fraction played an important role. In some concrete and bituminous pavements, a typical pattern of surface damage was also found associated to the application of deicers. In order to prevent damage to concrete and bituminous pavements by frost susceptible aggregates, they must be identified by reliable testing procedures. Sometimes the identification of potentially deleterious aggregates is based on their physical properties alone, and some other times the identification is based on their performance under freezing and thawing surrounded by mortar. Neither method has been entirely successful; however, from extensive experimental studies, the most significant factors involved in frost action have been identified. In this respect, strong evidence has been reported regarding the importance of the pore structure of coarse aggregates in their potential resistance to freeze-thaw action. The present study was designed to investigate the significance of the details of the pore structure on the frost resistance of concrete aggregates. Likewise, the surface failure taking place in concrete and bituminous pavements exposed to deicers was closely analyzed. Two approaches were used to accomplish the objectives of this investigation: Statistical Analysis of observational data, and the Experimental Method. In addition, a simplified theoretical analysis of the freezing process was offered. Based on field data, a discriminating function was obtained to differentiate between aggregates of varying frost resistance. This function was derived by taking into consideration the details of the pore structure of coarse aggregates in concrete pavements