## 4 Experimental Results: Short Beams
### HNSW-Transducer Measurements  
Figure 7a-d show one of the fifty waveforms recorded by the transducer P1 when it was placed above the beams with water in excess. To ease the readability of the time waveforms, the amplitudes were offset. Figure 7e-h are the close-up view of Figure 7a-d, and they reveal some variation in the TOF between the pristine and the conditioned samples. In what follows, the time waveforms are analyzed to validate the hypothesis that the differences are due to the presence of unwanted water. Figure 7: The time waveforms and their close up views obtained from the short beam tests: (**a**) condition 1; (**b**) condition 2; (**c**) condition 3; and (**d**) condition 4; (**e**), (**f**), (**g**), and (**h**) are the close views of (**a**), (**b**), (**c**), and (**d**), respectively. Table 5 summarizes the results associated with the beam subject to Condition 1, _i.e._, with the presence of 12.7 mm (0.5 in.) of standing water at the bottom of the formwork. The average value of the fifty TOF measurements per transducer is listed along with the corresponding elastic modulus. The data refer to the beam both top and bottom face. The latter was exposed to the presence of water. However, as is said earlier and displayed in Figure 2a, water migrated toward the top due to vibration and the weight of the concrete. The mean of the twelve moduli is presented in the shaded row along with the corresponding standard deviation and RSD. Surprisingly, the modulus estimated at the top surface is higher than the modulus at the bottom where the standing water was originally located. The results are therefore consistent with the empirical evidence that water migrated to the top and the experimental procedure that water was mixed with the concrete throughout the specimen. The RSD associated with the measurement at the top is almost double the corresponding value at the bottom. This is the result of point-by-point variations due to the presence of water whereas the conditions at the bottom were more uniform due to the self-weight of the concrete and the smoothness of the mold. We will observe that this consideration about the RSD applies to all four conditions. The last three rows of Table 5 list the elastic modulus of the baseline cylinders predicted by the same transducers. They are presented here again to ease the prediction of the resulting \(w/c\) ratio at the two surfaces of the beams. By comparing the values relative to the beams and to the cylinders, the solitary wave based technique estimates a ratio higher than 0.50 at the top and around 0.46-0.47 at the bottom of the short beams. Similar to Table 5, Table 6 presents the results relative to Condition 2 where the amount of standing water was half the amount in Condition 1. By looking at the mean of the elastic modulus, we observe that the value relative to the top surface is very close to the value reported in Table 5, whereas the \(w/c\) ratio estimated at the bottom is 0.45. The results suggest that the difference in the amount of standing water between Conditions 1 and 2 was not relevant to change the \(w/c\) ratio of the overall beam. By looking at the three bottommost rows of Table 6, we can reach the same conclusions for both conditions: the HNSW transducers were able to capture the circumstance that the short beams were corrupted by water in excess.