PSI - Issue 64

Jian-Neng Wang et al. / Procedia Structural Integrity 64 (2024) 1605–1612 / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 5. (a) Plot of the transmission loss versus aqueous samples of fresh concrete supernatant (W/C = 0.35) with sodium chloride solutions in different concentration ranges from 0.015% to 12.5%; (b) Plot of the transmission loss versus aqueous samples of fresh concrete supernatant (W/C = 0.65) with sodium chloride solutions in different concentration ranges from 0.015% to 12.5%.

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Fig. 6. (a) Plot of the chloride ion concentration versus aqueous samples of fresh concrete supernatant (W/C = 0.35) with sodium chloride solutions in different concentration ranges from 0.015% to 12.5% using the chloride ion-selective electrode (ISE) sensor; (b) Plot of the chloride ion concentration versus aqueous samples of fresh concrete supernatant (W/C = 0.65) with sodium chloride solutions in different concentration ranges from 0.015% to 12.5% using the chloride ion-selective electrode (ISE) sensor. 3.2. Optical fiber pH sensing in standard solutions For the results of this optical fiber pH sensing different pHs of the standard solutions, Fig. 7 (a) shows the transmission spectra of sensing different pHs of the standard solutions; Fig. 7 (b) displays the enlarged transmission spectra of sensing different pHs of the standard solutions (500-800 nm). Fig. 8 is the plot of the maximum intensity (counts) versus different pHs of the standard solutions. A linear fit (adj. R-Square = 0.91367) for the graph of sensing response, maximum intensity (counts), as a function of the different pHs of the standard solutions for this optical fiber pH sensing system (see Fig. 8). Based on the optical fiber sensing results, we found a linear increase in the maximum intensity (counts) as the pH of standard solution increased from1 to 9.75.