## 5 Conclusions  
From the work presented in this paper, the following conclusions can be drawn:  
1. The experimental results suggest that a 50% change in UGWL data may be the threshold to be considered as a \"significant change\" in the condition of the rebar or the rebar-concrete interface with respect to corrosion progression in RC bridge decks. While a 50% change provided a permanent change in the data that presents a higher certainty of deterioration, it was verified by visual inspection that UGWL amplitude changes as small as 17% can indicate an onset of corrosion activity. 2. While a larger data population is needed to confirm this finding, less than a 40% change in the UGWL amplitudes correlates to the CTL threshold of 0.1% by weight of concrete established by ACI 318. 3. The findings suggest that when UGWL and HCP are benchmarked, most of the data were in good agreement. The UGWL measurements presented notablechanges in amplitude as early as 9 days, compared to 30 days with HCP. As such, UGWL may have the ability to detect corrosion activity sooner than HCP. In addition to earlier detection, UGWL allows for higher certainty in predictions compared to HCP's large region of uncertainty, ranging between a 10 and 90% probability of corrosion activity. 4. The experimental results also indicate that noticeable changes in the UGWL readings were recorded as early as 9 days for the lab specimens submerged in 10% NaCl. Over 175 days, the change in the UGWL amplitudes were as high as 154% with respect to the baseline. The 154% increase in the UGWL amplitude change correlated to a 0.84% chloride content, which is higher than the threshold of 0.1% by concrete weight specified by ACI 318. This finding suggests a strong potential for the proposed UGWL method for corrosion monitoring. 5. UGWL has the potential to become a method that can detect multiple flaws with a single setup, because several other advantages of UGWL over HCP are identified in previous work, such as (1) UGWL can be used on epoxy-coated bars, while HCP is limited to use with black bars; and (2) UGWL can detect various flaws (corrosion, delamination, and independent cracks) with one setup, whereas HCP only detects corrosion. As such, UGWL has the potential to become a method that can detect multiple flaws with a single setup. To improve this new method's ability in the detection of corrosion in RC structures, future work will involve determining the chloride content at different stages of the NaCl submersion process, as well as at different depths from the concrete's surface. Conceptualization, A.S.A. and E.E. ; investigation, A.S.A., E.E., and D.R.-E.; methodology, A.S.A., E.E., and D.R.-E.; project administration, E.E; supervision, E.E. ; writing--original draft preparation, A.S.A. and E.E. ; writing--review and editing, A.S.A., E.E., and D.R.-E. All authors have read and agreed to the published version of the manuscript. This research was funded by the Nebraska Department of Transportation (NDOT) under grant number SPR-P1(19) M086. Any opinions presented in this paper reflect those of the authors and do not necessarily represent those of the funding agency. Not applicable. This research was funded by the Nebraska Department of Transportation (NDOT). The opinions stated in this paper belong to the authors, and do not necessarily reflect those of the funding organization. The Durham Science Center at the University of Nebraska-Omaha is acknowledged for their support with chloride testing on concrete samples. The authors also present their gratitude to the following undergraduate researchers who assisted in this research: [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON]. The authors declare no conflict of interest.