Investigation of the Interfacial Transition Zone between Aggregate-Cement Paste by AC Impedance Spectroscopy  

作　　者：孔丽娟 hou lirong wang yuhua sun guowen 

机构地区：[1]School of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043, China

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2016年第4期865-871,共7页武汉理工大学学报（材料科学英文版）

基　　金：Funded by the National Natural Science Foundations of China(Nos.51108282 and 51478278);the Excellent Youth Scholars of University Science and Technology Research of Hebei Province(No.Y2011111)

摘　　要：Three different types and sizes of coarse aggregate were chosen,and the alternating current（AC） impedance of cement paste samples with and without aggregate was measured at different curing ages.Based on Song’s equivalent circuit model,the electrical properties from the AC impedance results were obtained,and the resistance of connected pores RCCP was used to characterize the microstructure of the interfacial transition zone（ITZ）.The results show that the RCCP of concrete sample with aggregate is lower than that of cement paste sample,which indicates that the introduction of aggregate in cement paste makes the ITZ porous.Furthermore,for the same type of aggregate,an increase in particle size leads to a more porous ITZ,which accounts for the “water effect” and a larger aggregate would accumulate a thicker water film around it.In addition,for the same size of aggregate,the physical interaction between aggregate and cement paste is dominant in early age,and the microstructure of the ITZ around limestone aggregate is denser,which mainly depends on its rough surface and high water absorption.However,the microstructures of the ITZ around granite and basalt aggregates are denser in later age,which may be due to their higher chemical activity,and the chemical interaction between them and cement paste resulting in the generation of more hydrates.AC impedance spectroscopy thus proves to be powerful for evaluation of the microstructure of the ITZ.Three different types and sizes of coarse aggregate were chosen,and the alternating current（AC） impedance of cement paste samples with and without aggregate was measured at different curing ages.Based on Song’s equivalent circuit model,the electrical properties from the AC impedance results were obtained,and the resistance of connected pores RCCP was used to characterize the microstructure of the interfacial transition zone（ITZ）.The results show that the RCCP of concrete sample with aggregate is lower than that of cement paste sample,which indicates that the introduction of aggregate in cement paste makes the ITZ porous.Furthermore,for the same type of aggregate,an increase in particle size leads to a more porous ITZ,which accounts for the “water effect” and a larger aggregate would accumulate a thicker water film around it.In addition,for the same size of aggregate,the physical interaction between aggregate and cement paste is dominant in early age,and the microstructure of the ITZ around limestone aggregate is denser,which mainly depends on its rough surface and high water absorption.However,the microstructures of the ITZ around granite and basalt aggregates are denser in later age,which may be due to their higher chemical activity,and the chemical interaction between them and cement paste resulting in the generation of more hydrates.AC impedance spectroscopy thus proves to be powerful for evaluation of the microstructure of the ITZ.

关 键 词：aggregate paste impedance hydration curing Paste limestone sizes characterize porous 

分 类 号：TU528[建筑科学—建筑技术科学] TQ172.1[化学工程—水泥工业]