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活性粉末混凝土(RPC)高温下易发生爆裂破坏,升温时RPC微细观孔隙结构与内部蒸汽压的变化与爆裂密切相关.本文采用压汞和SEM方法测试了素RPC200在室温至350°C七个温度水平下的微细观孔隙结构特征,分析了比孔体积、阀值孔径、最可几孔径等孔隙特征参数随温度变化的规律.通过自行研制的蒸汽压装置量测并分析了温升过程中素RPC200内部蒸汽压的变化机制.采用“薄壁球”模型定量分析了孔隙内部蒸汽压引发RPC爆裂的力学机理,并给出了球壁任意点的应力随饱和蒸汽压q(T)、球壁特征尺寸K变化的力学计算模型.研究表明:随温度升高,素RPC200的比孔体积、平均孔径、阈值孔径、最可几孔径等孔隙特征参数明显增大,200°C是阈值孔径和最可几孔径明显增加的门槛温度.单位质量的RPC孔隙体积增大主要来自于过渡孔与毛细孔的数量与体积增加.由于未形成有利于蒸发水逃逸的孔隙通道,快速达到饱和且难以有效释放的内部蒸汽压是导致RPC高温爆裂的直接原因.作者利用“薄壁球”模型给出了对爆裂起控制作用的壁厚范围.
The reactive powder concrete (RPC) is prone to burst failure at high temperature, and the change of RPC microscopic pore structure and internal vapor pressure is closely related to the burst at elevated temperature.This paper uses mercury intrusion and SEM methods to test the stability of RPC200 at room temperature to 350 ° C Temperature characteristics of microscopic pore structure, the pore volume, pore size, the most pore size and other pore characteristics of the parameters of the law with temperature changes were measured by the vapor pressure device developed by measuring and analyzing the process of temperature rise The mechanical mechanism of vapor pressure-induced RPC burst was quantitatively analyzed by “thin-walled ball ” model, and the relationship between the stress at any point of the spherical wall and the saturated vapor pressure q (T), the ball The results show that pore volume, average pore size, thresholded pore diameter and most probable pore size of porous RPCs significantly increase with the increase of temperature, and 200 ℃ is the threshold pore size and The pore temperature can be significantly increased the most threshold temperature per unit mass of RPC pore volume increases mainly due to the transition pore and the pore volume and volume increase due to the formation of the water is not conducive to evaporation Yi pore channels, and difficult to quickly reach the saturated vapor pressure effective to release the internal temperature is the direct cause of RPC burst. Use of “thin Squash ” burst model gives a range of thickness functions as a control.