荷载和试件形状对水泥基材料碳化反应孔结构分形特征的影响  

Influence of load and specimen shape on pore structure fractal feature of cement-based material in the carbonation reaction

作　　者：韩萍[1] 韩建德[1] 王曙光[1] 刘伟庆[1] 

机构地区：[1]南京工业大学土木工程学院,江苏南京211816

出　　处：《混凝土》2014年第8期57-60,73,共5页Concrete

基　　金：国家973计划"城市轨道交通地下结构性能演化与感控基础理论"(2011CB013802);国家自然科学基金(51308290);江苏省自然科学基金(BK20130947);高性能土木工程材料国家重点实验室开放基金(2012CEM002);江苏省土木工程材料重点实验室开放基金(CM2013-01)

摘　　要：利用MIP压汞仪对碳化反应前后不同荷载应力水平和不同试件形状的孔结构信息进行定量研究，利用分形理论中的热力学分形模型计算出各组试样的孔表面积分形维数，分形维数越大表示孔结构的曲折和复杂程度越大，有害侵蚀性介质传输难度增加。研究结果表明：利用分形理论中的热力学分形模型可以定量地表述孔结构的变化，其数值结果在拓扑维数2.0和2.7之间。荷载影响下砂浆试样的孔表面积分形维数的分维值在2.1～2.5之间；对应力水平为0.2的试样，拉应力作用下其孔表面积分形维数的分维值比压应力作用下的大；对应力水平为0.4，0.6的试样，其拉应力作用下的分维值比压应力作用下的小。不同形状的水泥基试样其孔表面积分形维数在2.0～2.7之间，碳化前后其分维值都减小，但是块状试件的分维值减小的幅度比圆柱状试件要大。With MIP mercury intrusion microscopic test,a quantitative study was conducted on the pore structure with different load stress level and specimen shape before and after carbonation. The fractal dimension is larger ,means the tortuous and complex degree of pore structure are more,and harmful erosion medium is more difficulty. Based on thermodynamic fractal model ,the change of the external fractal dimension was analyzed before and after carbonation. The study reveals that the fractal dimension of thermodynamic fractal model can characterize the changes of the samples pore structures. The numerical result is between 2.0 and 2.7. Pore external fractal dimension of mortar specimen is between 2.1 and 2.5 under load. Sample,whose stress level is 0.2,the external fractal dimension under the action of tensile stress is larger than that under the action of compressive stress. However,sample,whose stress level is 0.4 and 0.6,the conclusion is opposite. On the other hand,pore external fractal dimension of cement-based specimen is between 2.0 and 2.7 for different shapes samples. Their fractal dimension values were decreased before and after carbonization ,but the fractal dimension values of massive specimens decrease amplitude is bigger than cylindrical specimens.

关 键 词：水泥基材料 碳化 孔结构 热力学分形模型 荷载 试件形状 

分 类 号：TU528.01[建筑科学—建筑技术科学]