## 2 Experimental Setup  
### Materials  
To set the baseline data, eighteen concrete cylinders were cast and tested: nine were evaluated nondestructively, whereas the remaining nine were tested according to the ASTM C469. The cylinders were 152.4 mm (6 in.) in diameter and 304.8 mm (12 in.) high. Three \(w/c\) ratios, namely 0.42, 0.45, and 0.50, were considered. The materials are listed in Table 1a and the mixture designs are presented in Table 1b. To ease identification, we labeled the samples according to Table 1c. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Batch** & **1** & **2** & **3** \\ \hline \(w/c\) ratio & 0.42 & 0.45 & 0.50 \\ Paste vol./concrete vol. & 0.30 & 0.30 & 0.30 \\ Air content (\%) & 6.50 & 5.00 & 6.25 \\ Coarse agg. (kg/m\({}^{3}\)) & 1054 & 1054 & 1054 \\ Fine agg. (kg/m\({}^{3}\)) & 666 & 666 & 666 \\ Cement (kg/m\({}^{3}\)) & 303 & 291 & 274 \\ GGBFS (kg/m\({}^{3}\)) & 101 & 97 & 91 \\ Water (kg/m\({}^{3}\)) & 170 & 175 & 183 \\ Slump (mm) & 133 & 95 & 203 \\ \hline \hline \end{tabular}
\end{table} 
Table 1c: Detailed information about the concrete cylinders. The samples evaluated with the HNSW (highly nonlinear solitary wave)-transducers were wet and tested after 28 days of curing. The samples evaluated with the UPV (ultrasonic pulse velocity) were wet and tested after 29 days of curing. The samples subjected to compressive load were tested saturated after 28 days of curing. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Material** & **Specific Gravity** & **Water Absorption Capacity (\%)** \\ \hline Cement & 3.15 & n/a \\ Coarse aggregate & 2.71 & 0.50 \\ Fine aggregate & 2.67 & 1.24 \\ GGBFS [1] & 2.83 & n/a \\ \hline \hline \end{tabular}
\end{table} 
Table 1a: Material used in the concrete mixtures. Then, sixteen 15.2 cm \(\times\) 15.2 cm \(\times\) 30.4 cm (6 in. \(\times\) 6 in. \(\times\) 12 in.) beams were fabricated using concrete mix design with \(w/c\) = 0.42. The beams were subject to the four different scenarios sketched in Figure 1. Each scenario represented either two surface finishing or two standing water situations in the formworks. Conditions 1 and 2 reflected the field case where water accumulates on the formwork as a result of rainfall prior to the placement of the concrete. To create Conditions 1 and 2, a predetermined volume of water based on the surface area of the beam mold was measured and poured on the sealed molds. Concrete was placed as evenly as possible into the molds and a shaft vibrator was then used to consolidate the concrete mixture before finishing the top surface. During the fabrication, the standing water was seen migrating to the top as shown in Figure 2a. After consolidation, the top surfaces of the beam molds were finished. Figure 1: Schematics of the four conditions simulated on the 152.4 \(\times\) 152.4 \(\times\) 254 mm\({}^{3}\) concrete beams. **(a)** Condition 1 in which 12.7 mm of water sits at the bottom of the form mimicking standing water on the formwork before concreting; **(b)** Condition 2 in which 6.35 mm of water sits at the bottom of the form mimicking standing water on the formwork before concreting; **(c)** Condition 3 in which 2.54 mm of water is sprinkled at the top of the beam mimicking rainfall during concreting; **(d)** Condition 4 in which 3.81 mm of water is sprinkled at the top of the beam mimicking rainfall during concreting. Figure 2: Photos of the preparation of the samples. **(a)** close-up view of one of the samples under Condition 2; standing water from bottom of beam mold migrates to the top; **(b)** preparation of one of the samples under Condition 3: finishing beam surface after second application of water; **(c)** rodding the same sample shown in **(b)** during the third and final application of surface water. Conditions 3 and 4 simulated instead the occurrence of rainfall during placement and finishing of the concrete. To create these conditions, a specific procedure was developed in an effort to best simulate the finishing of rainfall that would occur on a job site.