The compressive strengths of the prepared samples were measured according to displacement control at a constant rate of 1.0 mm/min. The hardened cement samples containing PET powder were crushed and ground into powder for characterization. Similarly, the PET powder samples immersed in different solutions were retrieved and vacuum filtered. The characterization techniques employed in this study include isothermal calorimetry, XRD, thermogravimetric analysis (TGA), FT–IR spectroscopy, and Raman spectroscopy.
Isothermal calorimetry was conducted using a three-point multipurpose conduction calorimeter (Tokyo–Riko Co., Ltd., Tokyo, Japan). Dry mixtures and water were mixed in the vessels, allowing the measurement of heat release at the start of mixing. XRD patterns were obtained using an X’Pert3–Powder X–ray diffractometer (PANalytical, Malvern, Worcestershire, UK), operating at 30 mA and 40 kV with Cu K-α radiation. The samples were scanned over a 2ϴ angle range of 5–65° with a step size of 0.026° for 1.5 h. TGA was conducted using DTG–60H (Shimadzu, Kyoto, Japan) at a heating rate of 10 °C/min in N2. FT–IR spectra were obtained using an FT–4100 spectrometer (JASCO, Tokyo, Japan). Raman spectra were obtained using an NRS–5100 Micro Raman Spectrometer (JASCO, Tokyo, Japan) with a 532-nm beam in the spectral range of 98–4000 cm−1.
Isothermal calorimetry was conducted using a three-point multipurpose conduction calorimeter (Tokyo–Riko Co., Ltd., Tokyo, Japan). Dry mixtures and water were mixed in the vessels, allowing the measurement of heat release at the start of mixing. XRD patterns were obtained using an X’Pert3–Powder X–ray diffractometer (PANalytical, Malvern, Worcestershire, UK), operating at 30 mA and 40 kV with Cu K-α radiation. The samples were scanned over a 2ϴ angle range of 5–65° with a step size of 0.026° for 1.5 h. TGA was conducted using DTG–60H (Shimadzu, Kyoto, Japan) at a heating rate of 10 °C/min in N2. FT–IR spectra were obtained using an FT–4100 spectrometer (JASCO, Tokyo, Japan). Raman spectra were obtained using an NRS–5100 Micro Raman Spectrometer (JASCO, Tokyo, Japan) with a 532-nm beam in the spectral range of 98–4000 cm−1.