房建工程中混凝土结构碳化的定量分析

Quantitative analysis of concrete structure carbonization in housing construction projects

利用多场耦合数值模型,对房建工程中的粗骨料取代率、环境温度、相对湿度和二氧化碳浓度等因素进行定量分析。结果表明,当房屋建筑是处于一种高温环境并且密封状态下的情况下,就会极大程度的引起建筑工程材料中碳化问题,而碳化发生几率中处于高温环境但是通风状况良好的房屋建筑次之,低温室外环境碳化程度最轻微。影响混凝土结构服役寿命的重要因素包括环境温度、粗骨料取代率、环境相对湿度。当相对湿度和粗骨料取代率一定时,粗骨料混凝土结构的使用寿命会伴随着房屋的内部温度的升高而出现降低的趋势;相比于二维碳化的情况而言,出现一维碳化现象的粗骨料混凝土结构的房屋建筑的使用寿命大约是二维碳化情况下的两倍。碳化速率系数的限值会伴随着房屋建筑设计使用年限的不断增加而呈现负相关趋势;即所有影响因素都基本保持一致的情况下,房屋建筑工程中混凝土的保护层的厚度越大的时候,就会加速碳化速率的系数限值;环境系数越大的时候,碳化速率系数限值就呈现负相关递减趋势,并且变化幅度较为显著。

The factors such as the replacement rate of coarse aggregate,ambient temperature,relative humidity and carbon dioxide concentration in housing construction projects are quantitatively analyzed by using a multi-field coupled numerical model.The results show that high-temperature indoor closed-loop environment is the most serious area of carbonization,followed by high-temperature indoor ventilation environment,and low-temperature outdoor environment is the least carbonization.The important factors affecting the service life of concrete structures include ambient temperature,replacement rate of coarse aggregate and ambient relative humidity.When the relative humidity and replacement ratio of coarse aggregate are constant,the service life of coarse aggregate concrete structure decreases gradually with the increase of temperature.Compared with two-dimensional carbonation,the service life of one-dimensional carbonation coarse aggregate concrete structure is about twice as long.The limit value of carbonization rate coefficient decreases gradually with the increase of design service life.The greater the thickness of concrete protective layer,the greater the limit value of carbonization rate coefficient.The larger the environmental coefficient,the smaller the limit value of carbonization rate coefficient,and the greater the change range.