Kim Junho, Na Seunghyun, Hama Yukio
Department of Architecture, National Institute of Technology, Oyama College, Nakakuki, Oyama-shi, Tochigi 323-0806, Japan.
Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan.
Materials (Basel). 2020 Oct 27;13(21):4787. doi: 10.3390/ma13214787.
The frost damage resistance of blast-furnace slag (BFS) cement is affected by carbonation. Hence, this study investigates the carbonation properties of pastes incorporating BFS with different replacement ratios, such as 15%, 45%, and 65% by weight, and different curing conditions, including air and carbonation. The BFS replacement ratio properties, determined by the Ca/Si ratio of calcium silicate hydrate in the cement paste sample, were experimentally investigated using mercury intrusion porosimetry, X-ray diffraction, and thermal analysis. The experimental investigation of the pore structure revealed that total porosity decreased after carbonation. In addition, the porosity decreased at a higher rate as the BFS replacement rate increased. Results obtained from this study show that the chemical change led to the higher replacement rate of BFS, which produced a higher amount of vaterite. In addition, the lower the Ca/Si ratio, the higher the amount of calcium carbonate originating from calcium silicate hydrate rather than from calcium hydroxide. As a result of the pore structure change, the number of ink-bottle pores was remarkably reduced by carbonation. Comparing the pore structure change in air-cured and carbonation test specimens, it was found that as the replacement rate of BFS increased, the number of pores with a diameter of 100 nm or more also increased. The higher the replacement rate of BFS, the higher the amount of calcium carbonate produced compared with the amount of calcium hydroxide produced during water curing. Due to the generation of calcium carbonate and the change in pores, the overall number of pores decreased as the amount of calcium carbonate increased.
高炉矿渣（BFS）水泥的抗冻融性受碳化作用影响。因此，本研究调查了掺加不同取代率（如按重量计15%、45%和65%）的BFS以及不同养护条件（包括空气养护和碳化养护）的净浆的碳化性能。通过水泥净浆样品中硅酸钙水化物的Ca/Si比确定的BFS取代率特性，采用压汞法、X射线衍射和热分析进行了实验研究。孔隙结构的实验研究表明，碳化后总孔隙率降低。此外，随着BFS取代率的增加，孔隙率降低的速率更高。本研究结果表明，化学变化导致BFS的取代率更高，从而生成了更多的球霰石。此外，Ca/Si比越低，源自硅酸钙水化物而非氢氧化钙 的碳酸钙量越高。由于孔隙结构的变化，碳化显著减少了墨水瓶状孔隙的数量。比较空气养护和碳化试验样品的孔隙结构变化，发现随着BFS取代率的增加，直径100nm或更大的孔隙数量也增加。BFS的取代率越高，与水养护期间产生的氢氧化钙量相比，产生的碳酸钙量越高。由于碳酸钙的生成和孔隙的变化，随着碳酸钙量的增加，孔隙总数减少。
