*2.1. Materials*

Two types of samples, namely mortar and concrete samples, were mixed, and ordinary Portland cement was used in both types of samples. The fine aggregate used in the two types of samples was river sand, and the relative density of this sand was 2.62. The coarse aggregate used in concrete samples was a dolomitic limestone with a relative density of 2.65. As shown in Table 1, the mortar samples were designed to span three water to cement ratios (w/c = 0.4, 0.45 and 0.5), and the w/c of the concrete sample was fixed to 0.5 to figure out the influence of coarse aggregate on the guided wave technique.

**Table 1.** Mixture designs and setting times of mortar and concrete samples.


–not applicable.
