Study On Preparation And Properties Of Conductive Lightweight Aggregate Concrete

Conductive concrete can apply for both deicing or melt snowing of road,airport runways and for heating, structural monitoring and so on.It is very real significant to carry out the work of conductive concrete materials.To adapt to the needs of social development and conservation resource.This thesis construct two new conductive concrete-black lightweight aggregate concrete and re-doped carbon black/carbon fiber lightweight aggregate concrete.Preparation processs,mechanical and electrical prop-erties and resistance variation with load of the two new conductive concrete were researched systematicly. The main researching content and results are as follows:(1) A better preparation process of carbon black lightweight aggregate concrete was obtained by comparing the effect of the different kinds of conductive carbon black, carbon black dispersions in different ratio, age on the electrical conductivity of the lightweight aggregate concrete. Carbon black lightweight aggregate concrete had electrical percolation phenomena and percolation threshold was about 0.83vol%. Compressive strength increased with increasing carbon content at first and then decreased, while the material density decreased with increasing the volume content of carbon black. When the carbon black content was 1.94vol%, cement-sand ratio of 2.43 to 5.2, the compressive strength can reach 34 to 38MPa, and resistivity was stabile, but the poor workability and processing difficulty.(2) To further enhance the mechanical properties of conductive concrete, a good process that using water-soluble carbon fiber Thin felt to prepare carbon fiber/ carbon black conductive lightweight aggregate was obtained by comparing 5 different preparation process of carbon black/carbon fiber conductive lightweight aggregate concrete. The resistivity of black lightweight aggregate concrete was decreased with the increase of carbon fiber. The total volume amount of carbon black and carbon fiber is less than that of single-doped carbon black, and mixing has better workability.(3) The bending properties of carbon black/carbon fiber lightweight conductive was studied. The result indicated that carbon fiber has a certain role in strengthening and toughening to black lightweight aggregate concrete. The bending strength of concrete increases with increasing cement/sand ratio, when the cement/sand ratio is 2.0, the bending strength reach 5.7MPa,but then become a very small change in bending strength. A mix of meeting the requirement of deicing or snow melting material was obtained according the requirements of bending, compression, and electrical conductivity.(4) The experiment that carbon/carbon fiber conductive lightweight aggregate concrete was loaded monotonously show that the resistance change rate decreased linearly before reaching limit load. The larger cement/sand ratio and the smaller the resistance,the smaller the range of resistance change rate.