Development of a Nondestructive Impulse Device and Damage Model for Unreinforced Concrete

Table 2

Frequency divided by initial frequency.

Mix	𝑓𝑖/ 𝑓𝑜
Low strength	89.11%
Low/medium strength	90.36%
Medium strength 1	90.13%
Medium/high strength	92.53%
High strength	93.30%