Calcium carbonate whisker (CW) can work as a cost-effective and environment friendly micro-fiber in reinforcing cementitious composites. Influence of high temperature on micro-structure of CW reinforced cement paste by nanoindentation and mercury intrusion porosimetry test is studied in this research. Up to 500∘C, the indentation depth, elasticity modulus, indentation hardness and interfacial transition zone (ITZ) width of CW reinforced cement paste are near or even better than that at room temperature, due to the coupling effect of CW transformation from aragonite to calcite and internal autoclaving. However, when the temperature is higher than 700∘C, nano-mechanical properties of CW reinforced cement paste degenerated significantly, due to the decomposition of CW and hydration products. Similarly, with the increase of temperature up to 400∘C, the porosity and pore size increase little or even decrease, while the fractal dimension of pore volume increases. With the introduction of CW, the pore parameters and fractal dimension are decreased up to 400∘C, due to the filler effect of CW. When the temperature is higher than 700∘C, the pore diameter and fractal dimension of CW reinforced cement paste are significant higher than that of pure cement paste, due to the decomposition of CW and hydration products. In CW reinforced cement paste, the fractal dimension was increased with the increased temperature and porosity in this research. There are negative correlations between the pore volume fractal dimensions and the strengths of CW reinforced cement paste. Fractal dimension is a useful tool to evaluate the change of pore structure at high temperature.

中文翻译：

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碳化钙晶须增强水泥浆在高温（高达900℃）后的纳米压痕和孔隙率分形维数

碳酸钙晶须 (CW) 可以作为一种具有成本效益和环境友好的微纤维用于增强水泥基复合材料。本研究通过纳米压痕和压汞法研究高温对CW增强水泥浆体微观结构的影响。最多 500 个∘C、CW增强水泥浆体的压痕深度、弹性模量、压痕硬度和界面过渡区（ITZ）宽度接近甚至优于室温，这是由于文石向方解石的CW转变和内部高压灭菌的耦合作用. 但是，当温度高于 700∘C，由于CW和水化产物的分解，CW增强水泥浆体的纳米力学性能显着退化。同样，随着温度升高到 400∘C、孔隙率和孔径增加不大甚至减小，而孔体积的分形维数增加。随着CW的引入，孔隙参数和分形维数降低到400∘C、由于CW的填充效果。当温度高于700∘C，由于CW和水化产物的分解，CW增强水泥浆体的孔径和分形维数显着高于纯水泥浆体。在本研究中，在 CW 增强水泥浆体中，分形维数随着温度和孔隙率的增加而增加。孔隙体积分形维数与CW增强水泥浆体强度呈负相关。分形维数是评价高温下孔隙结构变化的有用工具。