负温环境下混凝土孔结构与强度和渗透性的关系  

Pore Structure of Concrete at Negative Temperature Curing inRelation to Strength and Penetration

作　　者：段运[1] 杨子江[1] 王起才[2] 张戎令[2] 吴朝阳 薛彦瑾 魏定邦 DUAN Yun;YANG Zijiang;WANG Qicai;ZHANG Rongling;WU Chaoyang;XUE Yanjin;WEI Dingbang(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;National and Provincial Joint Engineering Laboratory of Road&Bridge Disaster Prevention and Control,Lanzhou 730070,China;Gansu Province Transportation Planning,Survey and Design Institute Co.,Ltd.,Lanzhou 730030,China)

机构地区：[1]兰州交通大学土木工程学院,兰州730070 [2]兰州交通大学道桥工程灾害防治技术国家地方联合工程实验室,兰州730070 [3]甘肃省交通规划勘察设计院股份有限公司,兰州730030

出　　处：《材料导报》2022年第15期68-73,共6页Materials Reports

基　　金：国家自然科学基金(51768033)。

摘　　要：为探究多年冻土区混凝土孔结构与其抗压强度和氯离子渗透性之间的关系,依据多年冻土区地层温度,设计了负温(-3℃)环境下三种强度等级的混凝土的抗压强度、抗氯离子渗透性和孔结构试验。结果表明,负温养护下,混凝土中200 nm以上孔的比例显著增加,阈值孔径增大,分形维数减小;标养和负温下混凝土的临界孔级分别为50~100 nm和100~200 nm,负温养护使得临界孔级增大;负温养护并未改变混凝土的抗压强度与分形维数、孔隙率以及平均孔径之间的正负相关性,但却降低了它们之间的相关程度;双参数模型能准确描述混凝土强度与其孔隙率和平均孔径之间的定量关系;混凝土的氯离子迁移系数与阈值孔径平方呈正比例关系,与分形维数呈负线性相关,减小阈值孔径可以有效提高混凝土的抗渗性。To explore the relationship between the pore structure of concrete and its compressive strength and chloride ion permeability in permafrost regions,tests of compressive strength,its resistance to chloride ion penetration and pore structure are designed for concretes with three different strength grades at negative temperature(-3℃),based on the ground temperature in permafrost regions.The results show that the proportion of pores above 200 nm significantly increases in the concrete cured at negative temperature,with the threshold pore diameter of concrete increased and the fractal dimension of concrete decreased simultaneously.The critical pore levels of concretes cured at standard and negative temperatures are 50—100 nm and 100—200 nm,respectively.The critical pore levels are significantly increased due to negative temperature curing.The relationship between the compressive strength of concrete and its fractal dimension,porosity and average pore diameter still shows the positive and negative correlation under negative temperature curing,but the degree of correlation between them is reduced.The dual-parameter regression model can accurately describe the quantitative relationship between the strength of concrete and its porosity and average pore diameter.The chloride ion migration coefficient of concrete is positively correlated with the square of the threshold pore diameter and negatively linearly correlated with the fractal dimension.Reducing the threshold pore size can effectively improve the impermeability of concrete.

关 键 词：阈值孔径 临界孔级 分形维数 双参数模型 

分 类 号：TU528[建筑科学—建筑技术科学]