Methods for Assessing Concrete Segregation Due to Compaction

Segregation in concrete significantly affects its durability and structural integrity by introducing local variance in both the strength distribution and the modulus of elasticity within a structural element. Additionally, segregation can lead to durability complications, such as shrinkage induced cracking. Recent observations have identified such segregation issues in already existing structures, underscoring the importance of assessing segregation. In this study, we evaluate the extent of segregation in normally vibrated concrete specimens, which were subjected to different vibration durations and vibrated using either table or poker vibrators. The research introduces three segregation indices to assess this phenomenon. One index relies on the standard deviation of densities across multiple slices of each specimen, while the other two utilize Digital Image Processing (DIP) to analyse the distribution of aggregates in horizontal and vertical slices, respectively. High correlations were found between the density-based index and vibration time for both poker-vibrated and table-vibrated specimens. The DIP-based indices showed strong correlations with the density-based approach, offering quicker alternatives for assessing segregation. The study further proposes classification levels for segregation based on these methods and reveals the negative impact of increased air entrainment on segregation. These findings provide insights for optimizing concrete compaction processes and understanding segregation.