温湿度耦合作用下混凝土氯离子浓度场研究

发布时间：2018-04-04 20:33

本文选题：温度　切入点：混凝土　出处：《青岛理工大学》2015年硕士论文

【摘要】：氯离子渗透到混凝土内部导致钢筋锈蚀是海洋及西部盐湖/盐渍土环境下混凝土结构破坏的主要因素。氯离子在混凝土中的渗透过程不仅受到材料自身性能的影响,也受到外部环境的影响,尤其是外部温湿度环境作用。为了揭示混凝土在环境作用下的温湿度场响应,及其对氯离子传输的影响,本文通过在不同温湿度环境下进行升温、降温、毛细吸盐试验和导热系数测定试验等进行综合分析,研究表明:(1)随着混凝土内部相对湿度(Iternal Relative Humidity:IRH)的增加,热量传递速度逐渐加快。距离热源越近的位置,混凝土的热响应速度越快,升温、降温过程中所需的时间越少。(2)距离底面越近的位置,湿度的增长速度越快,稳定状态的湿度值也较大。随着内部相对湿度的增大,混凝土达到环境温度所需时间越短。(3)随着外部环境温度的升高,混凝土的单位面积毛细吸水量和吸收系数逐渐增大,且毛细吸收系数与温度的变化关系符合阿累尼乌斯公式。内部相对湿度增加,吸水量和吸收系数都逐步减小,且混凝土毛细吸收系数随着湿度的增大具有线性减小的趋势。(4)混凝土的湿度扩散系数随着温度的升高而增大,导热系数随着内部相对湿度和龄期的增加而增大,且在28d内增加较为迅速,之后较为缓慢。(5)随着混凝土内部湿度的增加,氯离子的传输系数呈线性减小趋势。随着外部温度的升高,氯离子传输系数逐渐增大,且扩散系数与温度的演变关系符合阿累尼乌斯方程。(6)粉煤灰掺量增加,混凝土的单位面积吸水量和毛细吸收系数整体都呈现减小趋势。矿粉掺量增加,吸水量逐渐减小,而当掺量达到50%时,吸水量又出现随掺量增大而略微增加的趋势。(7)复掺矿粉和粉煤灰的LF50混凝土,导热系数、热响应速度、湿度的增长速度、湿度扩散系数和氯离子传输系数都小于L50纯水泥混凝土,所以LF50混凝土氯离子的渗透速度较慢。
[Abstract]:The corrosion of steel bar caused by chloride ions permeating into the concrete is the main factor of concrete structure damage in the sea and western saline lake / saline soil environment.The permeation process of chloride ions in concrete is affected not only by the properties of the material itself, but also by the external environment, especially the external environment of temperature and humidity.In order to reveal the temperature and humidity field response of concrete under environmental action and its influence on chloride ion transport, this paper makes a comprehensive analysis by means of temperature rise, cooling down, capillary salt absorption test and thermal conductivity measurement test in different temperature and humidity environments.The results show that the heat transfer rate increases gradually with the increase of internal relative humidity (Iternal Relative humidity: IRH).The closer the heat source is, the faster the thermal response speed of concrete is, and the shorter the heating time is, the less time is needed to reduce the temperature, the closer to the bottom surface, the faster the growth rate of humidity is, and the higher the humidity value is in the stable state.With the increase of internal relative humidity, the shorter time it takes for concrete to reach the ambient temperature, the smaller the amount of capillary water absorption and the absorption coefficient of concrete per unit area increase with the increase of external ambient temperature.The relation between capillary absorption coefficient and temperature is in accordance with Arrhenius formula.With the increase of relative humidity, the water absorption and absorption coefficient decrease gradually, and the capillary absorption coefficient of concrete decreases linearly with the increase of humidity.The thermal conductivity increases with the increase of internal relative humidity and age, and increases more rapidly in 28 days, then slowly. 5) with the increase of internal humidity of concrete, the transport coefficient of chloride ion decreases linearly.With the increase of external temperature, the chloride ion transport coefficient increases gradually, and the relationship between diffusion coefficient and temperature is in accordance with the Arrhenius equation.The water absorption per unit area and the capillary absorption coefficient of concrete are decreasing as a whole.With the increase of mineral powder content, the water absorption decreases gradually, and when the mineral powder content reaches 50, the water absorption increases slightly with the increase of mineral powder and fly ash content. The LF50 concrete mixed with mineral powder and fly ash has thermal conductivity, thermal response speed and humidity growth rate.The moisture diffusion coefficient and chloride transport coefficient are lower than that of L50 pure cement concrete, so the permeation rate of chloride ion in LF50 concrete is slower than that in L50 pure cement concrete.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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