Assessing the effect of different compaction mechanisms on the internal structure of roller compacted concrete

Compaction plays a pivotal role in the formation of the aggregate skeleton of concrete mixtures, especially for stiff mixes such as Roller Compacted Concrete (RCC). RCC is compacted in the field with combinations of different energies (kneading/shear, impact, static & vibratory pressure), whereas various compactors are used, viz. modified Proctor (MP), vibratory hammer (VH), vibratory table (VT), and gyratory compactor (GY) in the laboratory to mimic the field compaction. Since the compaction mechanism is different in these compactors compared to field rollers, the behaviour of RCC is also distinct and warrants a fundamental study. In this study, the dominating parameters affecting the mesostructural arrangement of aggregates within the concrete skeleton when compacted with different mechanisms are comprehensively studied and compared with the field com-pacted specimens using several image processing techniques. The mesostructural parameters considered are interparticle spacing & distribution, aggregates segregation, orientation, morphology & breakage post-compaction, and crack length. The results indicate a higher possibility of getting better aggregate distribution and strength while a lower segregation potential when compacted with VH, followed by MP. However, the use of MP could alter the aggregates' morphological characteristics due to the breakage of particles during the compaction process. On the other hand, VT and GY could exhibit similar interparticle distances to the field specimens but could not demonstrate similar performance in terms of strength and durability. The dominating parameters affecting aggregates' spatial distribution are found to be aggregate-to-mortar ratio, interparticle distance, and the mechanism associated with each compaction technique.

Automated summary

This study comprehensively compares the dominant parameters affecting the mesostructural arrangement of aggregates in concrete compacted with different mechanisms, and compares them with field compacted specimens. The results indicate that using a vibratory hammer and modified Proctor compactor can result in better aggregate distribution and strength, with a lower segregation potential. However, the use of the modified Proctor compactor may alter the aggregates' morphological characteristics due to particle breakage during the compaction process. On the other hand, the vibratory table and gyratory compactor can have similar interparticle distances to field specimens but may not exhibit similar performance in terms of strength and durability.