摘要
高温不仅降低砂浆的力学性能,还会对其耐久性产生重大的影响。通过高温马弗炉以3种不同升温速率(即5℃/min、10℃/min、15℃/min)加热砂浆至400℃、500℃、600℃来模拟火灾试验。通过新的试验技术(允许在围压下同时测量气体渗透性和孔隙率)研究了不同温度损伤后砂浆的气体渗透性和孔隙率以及力学性能的变化。结果表明,随着升温速率的加快以及温度的升高,砂浆气体渗透率与孔隙率逐渐增大。与未升温相比,当以15℃/min加热至600℃时,砂浆气体渗透率增加了2个数量级,孔隙率增大了1.77倍;在加卸载围压过程中,砂浆气体渗透率与孔隙率均不可逆地降低;升温速率越大,加热温度越高,砂浆气体渗透率与孔隙率对围压就越敏感。孔隙率对围压的敏感性与气体渗透率相比较小,但孔隙率对围压的敏感性证实了加卸载围压过程中裂纹不可逆闭合与孔隙不可逆破碎;当以3种升温速率加热砂浆至400℃、500℃和600℃时,随着升温速率的加快以及温度的升高,砂浆的抗压强度逐渐降低。
High temperature not only reduces the mechanical properties of mortar, but also has a great impact on its durability. The fire test was simulated by heating the mortar to 400 ℃, 500 ℃ and 600 ℃ by high temperature muffle furnace at three different heating rates(5 ℃/min, 10 ℃/min and 15 ℃/min). Throuth a new experimental technique allowing simultaneous measurement of gas permeability and porosity changes under confining pressure, the changes of gas permeability, porosity and mechanical properties of mortar damaged at different temperatures were studied.The main results show that the gas permeability and porosity of mortar increase gradually with the acceleration of heating rate and temperature. Compared with no heating, when heated to 600 ℃ at 15 ℃/min, the gas permeability of mortar increases by 2 orders of magnitude and the porosity increases by 1.77 times. In the process of loading and unloading confining pressure, the gas permeability and porosity of mortar decrease irreversibly. When the heating rate is faster and the heating temperature is higher, the gas permeability and porosity of mortar are more sensitive to confining pressure. The sensitivity of porosity to confining pressure is smaller than that of gas permeability, but the sensitivity of porosity to confining pressure confirms the irreversible closure of cracks and irreversible fracture of pores during loading and unloading confining pressure. When the mortar is heated to 400 ℃, 500 ℃ and 600 ℃ at three heating rates, the compressive strength of the mortar decreases gradually with the acceleration of heating rate and the increase of temperature.
作者
陈伟
盛明泉
许澳
梁越
CHEN Wei;SHENG Mingquan;XU Ao;LIANG Yue(College of Civil Engineering,Architecture and Environment,Hubei University of Technology,Wuhan 430068,China)
出处
《硅酸盐通报》
CAS
北大核心
2022年第4期1256-1263,共8页
Bulletin of the Chinese Ceramic Society
基金
国家自然科学基金(51709097)。
关键词
砂浆
火灾模拟
高温
升温速率
气体渗透性
孔隙率
力学性能
mortar
fire simulation
high temperature
heating rate
gas permeability
porosity
mechanical property
