A better way to state this question would be “should all placed concrete be consolidated.” Why? There is more than one way to consolidate concrete and one way being by mechanical vibration. Mechanical vibration of concrete is the typical method of concrete consolidation. However, there are other methods such as rodding, but they tend not to be as efficient as mechanical vibration.
Yes, all concrete should be consolidated. Contractors tend to use mechanical vibrators such as spud vibrators, vibratory screeds, and form vibrators. Contractors tend to use spud vibrators for formed structures such as foundation walls, footings, elevated slabs, etc. Vibratory screeds are used for slab on grades, which is typically suitable for consolidating concrete up to 8 inches thick.
Concrete should be vibrated for a few reasons, but a major reason being concrete settlement. As previously mentioned in the article “Why Does Concrete Crack”, it was stated that concrete can crack from the settlement of the concrete itself. This settlement tends to occur from improper consolidation, which often leads to open voids and can eventually lead to cracking.
REFERENCES:
ACI 318-11 – Building Code Requirements for Structural Concrete (2011)
The Concrete Manual – Based on 2015 IBC and ACI 318-14 (2015)
