A study on measurement of water content of recycled gypsum derived from waste gypsum board using refractive index of aqueous glycerol solution

In this study, we discussed the calibration curves (experimental, theoretical, and approximate) for the refractive index of aqueous glycerol solution. Next, the results (refractive index) of the water content test using the glycerol method, which has been conducted on commercially available reagent gypsum that imitates recycled gypsum derived from waste gypsum board, were applied to three different calibration curves (experimental, theoretical, and approximate) and calculations were made to determine how much the different calibration curves used affect the water content value. The obtained results showed that the difference between the water content obtained by the glycerol method and the set water content increases as the set water content increases, and at a set water content of 300%, the difference between the water content obtained by the glycerol method and the set water content was 8.4% for the experimental method, 50.8% for the theoretical method, and 296.6% for the approximate method, and therefore, it was clear that the water content obtained by the experimental equation was sufficiently accurate.