Consolidation of Concrete with Epoxy-Coated Reinforcement

The specific objectives of this testing are as follows: (1) assess the damage to epoxy-coated reinforcing bars produced by metallic head and rubber head vibrators; (2) assess the quality of consolidation obtained with rubber head vibrators as compared with metallic head vibrators; (3) determine the degree and quality of consolidation obtained with rubber head vibrators as compared with metallic head vibrators through a visual examination and by measuring density of cores from vibrated specimens; and (4) make recommendations on the appropriate type of internal vibrator to be used in conjunction with epoxy-coated reinforcement.

Several test specimens were constructed to evaluate vibrator damage to coated reinforcing bars. Companion specimens simulating column, footing, and slab sections were assembled. Once specimen was vibrated with the rubber vibration head, while the metal head was used to consolidate the companion specimen. The amount of vibrator damage to reinforcement was assessed visually. For each specimen type, the metal vibrator heads produced significantly more damage than did rubber heads.

In a second series of tests, the vibratory action produced by rubber and metal vibrator heads was recorded using accelerometers. The measurement showed that during consolidation, the metal head produced more significant horizontal waves in the concrete than did the rubber head. Horizontal particle accelerations with the metal head were greater than those with the rubber head, both close to the insertion point of the vibrator, and farther out from this point. More significant differences were noted between the two heads at points father from the point of insertion.

Finally, a group of specimens consolidated using metal and rubber vibrator heads was cured and cores were removed. Cores from both metal and rubber head specimens revealed that more voids were located under reinforcing bars farther fromt he point of vibrator insertion than there were closer to the insertion point, even when the concrete at both locations was adequately consolidated.