[Retracted] Empirical Investigation on Compressive Strength of Geopolymer and Conventional Concretes by Nondestructive Method

Table 6

Grading of concrete using pulse velocity [8].

UPV (km/sec)	Quality of concrete
Above 4.5	Excellent (E)
3.5–4.5	Good (G)
3–3.5	Medium (M)
Below 3	Poor (P)