Preparation And Performance Investigation Of Iron Containing Aggregate And Its Cement-based Conductive Composites

Electrically conductive concrete is a kind of concrete owning special properties such as electrical conductivity, strength sensibility etc. In view of its special functions, Electrically conductive concrete has a broad application prospect in the field of civil engineering structure health monitoring and evaluation, airport and road deicing, room heating, and electromagnetic shielding etc. Aiming at solving the problem of common aggregates in concrete obstructing the distribution of conductive phases such as carbon fiber, and affecting the integrity and continuity of the conductive network, this thesis investigated the preparation and performances of iron-containing conductive functional aggregate and its cement-based composites, with the funding of national natural science foundation of China.The main research works and achievements are listed as follows:Iron containing conductive functional aggregate with excellent performances was prepared through raw materials power preparation, dry-pressing molding and calcinations processes, with clay used as pottery basis material and micro iron powder used as conductive component. The optimal calcinations temperature range and the mixture were determined by considering the variation of volume shrinkage and specific density.The mechanical properties and the electrical conductivity of the iron containing functional aggregate were studied. The results show that the particle size and the content of iron powder have remarkable influence on the conductivity and the mechanical properties. As the particle size of iron powder decreased, the conductivity of aggregate with the same iron powder content improved obviously. With the particle diameter of 3μm,6μm,48μm and 150μm, the conductive percolation threshold content of the iron powder were 9.82%,11.03%,18.01% and more than 18.01% in volume respectively.Diphase conductive cement based material was prepared utilizing iron containing conductive functional aggregate and carbon fiber. And the conductivity of it was compared with common aggregate concrete and pure cement paste reinforced with carbon fiber. It was found that the adding of conductive functional aggregate could obviously lower the resistivity of concrete, and shorten the time needed for resistivity stabilization. The reason for that was due to the conductive aggregate helped forming a more complete conductive network. Through unidirectional uniform loading experiment, the compressive sensibility of the conductive cement based material was investigated. Between the percolation content ranges, the compressive sensibility decreased with the increasing of carbon fiber content. And with the certain carbon fiber content, the adding of conductive aggregate improved the compressive sensibility. However, the adding of common aggregate lowered the compressive sensibility.