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Q. Does over-vibration cause segregation and loss of air content? A. Normal-density concretes that are well-proportioned and have adequate consistency are not readily susceptible to segregation resulting from over-vibration (ACI 309). A mixture with excess mortar is prone to segregation when over-vibrated, however. A well-proportioned mixture with the proper air-void system will lose some air during vibration. The system will still provide satisfactory resistance to freezing and thawing because the loss of air will be from large-size bubbles and it will not increase the bubble-spacing factor beyond acceptable limits. References: SP-1(02); ACI PRC-309.5-22 Topics in Concrete: Concrete Fundamentals; Consolidation of Concrete; Placing Concrete
Q. Does over-vibration cause segregation and loss of air content?
A. Normal-density concretes that are well-proportioned and have adequate consistency are not readily susceptible to segregation resulting from over-vibration (ACI 309). A mixture with excess mortar is prone to segregation when over-vibrated, however. A well-proportioned mixture with the proper air-void system will lose some air during vibration. The system will still provide satisfactory resistance to freezing and thawing because the loss of air will be from large-size bubbles and it will not increase the bubble-spacing factor beyond acceptable limits.
References: SP-1(02); ACI PRC-309.5-22
Topics in Concrete: Concrete Fundamentals; Consolidation of Concrete; Placing Concrete