Preparation And Research Of Cement-based Carbon Fiber Conductive Composites

Cement-based Carbon Fiber Conductive Composites(CCFCC) is a multifunction smart material and it play a important role in civil engineering to be intelligent. In this paper, Phosphate Cement-based Carbon Fiber Composite Materials(PCFCM, including PCFC paste and PCFM mortar) prepared using phosphate cement with high fly ash as matrix and short carbon fiber as function materials by mechanical mixing. Carbon Fiber Reinforced Cement-based Composite Materials(CFRCM) were prepared by using Portland cement as matrix, and preparing Sulphoaluminate cement Conductive Composite Mortar(SCCM) by using Sulphoaluminate mortar as matrix, carbon fiber, graphite and nano-zinc oxide as conducting medium. A comparative study of electrical conductivity between PCFCM and CFRCM is performed by measuring resistance and observe the distribution of the carbon fiber in the matrix by means of SEM, the conductivity model and the stability of conductivity in both PCFCM and SCCM were analyzed. At last, the pieo-resistivity of PCFCM is measured by a combination of AC bridge and universal testing machine. The following conclusion can be obtained.(a)The results showed that comparing with CFRCM, PCFCM not only is easy to be prepared but also higher in mechanical properties reinforced effect and better in electrical conductivity when they have same carbon weight. The reason is SEM image shows the distribution of carbon fiber in PCFCM is better than CFRCM when they have high fiber contain.(b)The electrical conductivity of PCFCM specimen which carbon fiber content are higher were less effected by age and drying time owing to the electrical conductivity networks in those specimen electrical oriented by electron conduction mechanism which formed by the contact between carbon fiber. The study shows when carbon dosage more than 1.4% in PCFC and carbon dosage more than 1.0% in FCFM, they will have stable electrical conductivity performance.(c)Under unidirectional and cyclical loading, the resistance change of carbon fiber can reflect the stress state of the structure, if contents suitable PCFCM, it is expected to be applied to structural stress and damage monitoring.(d)Under the condition of fixed water cement ratio, when the conductive powder dosage is suitable it can enhance SCCM conductive ability, once content is too high it will limit the dispersion degree of carbon fibers with bad flowability in SCCM caused by water been absorbed. So the results proved the appropriate water plays an important role in the preparation of good electrical conductivity performance of SCCM.