关键词: 高温碳化养护, 干硬性水泥净浆, 抗压强度, 碳化程度, 矿物成分

Abstract: Carbonation curing has attracted lots of research interests for the ability to improve early compressive strength and storage CO₂. However, the effect of high temperature on the carbonation process has been barely investigated. In the present study, 20 ℃, 100 ℃, 120 ℃, 140 ℃ and 160 ℃ were chosen for carbonation curing, the variation of compressive strength was investigated and the microstructural properties of carbonated dry-mixed cement pastes were evaluated by thermogravimetric analysis (TG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM). The results show that compressive strength and carbonation degree firstly increase with the increase of carbonation temperature and then became constant. The compressive strength of the sample cured at 20 ℃ is 14.8 MPa, while achieved about 4 times higher strength at 140 ℃ with recorded values of 71.2 MPa, which means that high temperature speeded the carbonation process. At such temperatures, part of the free water can be evaporated to enhance the CO₂ diffusion thus beneficial for a more complete carbonation reaction. Polymorphs of CaCO₃ are varied in samples carbonated with different carbonation temperatures. Compared to sample carbonated at 20 ℃, sample carbonated at 140 ℃ presented a higher proportion of aragonite and vaterite. Also, calcium silicate hydrate (C-S-H) generated from the sample carbonated at 140 ℃ is identified higher polymerization degree than that of sample carbonated at 20 ℃.

Key words: high temperature carbonation curing, dry-mixed cement paste, compressive strength, carbonation degree, mineral composition