The ICCP-SS System Of Cementitious Material Operation Performance And CFRP Recycling Method Research

Targeted at the problem of deterioration of reinforced concrete(RC) induced by steel corrosion, the method of improvement for the durability of RC structures is the major research. Based on the impressed current cathodic protection(ICCP) technique and structural strengthening(SS) method, which are the currently popular repaired measurements for the deteriorated concrete, the newly technique denominated by ICCP-SS that is the conbination of ICCP technique and SS method is proposed. The adhesive material in the ICCP-SS is the critical part used to make the integration between the dual functional material and concrete substrate so that it should keep excellent electricity conductivity and maintain sufficient interfacial bond property. However, the epoxy resin was commonly adopted in SS method for RC structures, it is restriction for combination between ICCP techniqe and SS method due to the nonconducting of the epoxy resin. Based on the sufficient strength performance and excellent electricity conductivity as well as good durability, the cementitious material would be adopted used as adhesive material in ICCP-SS. The carbon fiber reinforced polymer(CFRP) is also used as dual functional material which are the anode material and strengthening material simultaneously. The evolution of the performance of the proposed ICCP-SS would be investigated in this thesis. Besides, targeted at the problem of carbon fiber recycling, the electrochemical recycling method is proposed based on the principle of the subject to recycle the carbon fiber from CFRP. Therefore, a series of related research were designed, developed and achieved in this thesis.1) Cementitious material optimization research. For the requirement of both electrochemical and mechanical performance and property, the investigation of cementitious material optimization research begin in the consideraion of the property of material strength, electrical conductivity and interfacial shear strength. The re-dispersible powde is adopted which the weight is the 20% of the mass of both the cement and silicate powder. The modest amount of chopped catbon fiber is the 1% of the cement. Results show that the micro-structure of the cementitious material is a kind of interlocking each other between cement paste and high-molecular polymer which attribute to the increasing of property of adhesive.2) Performance of ICCP-SS technique. The cementitious material is used as adhesive material and the CFRP is applied as dual functional material to estabilish the ICCP-SS. The investigation of electrochemical and mechanical properties and interfacial acidification are studied out. The experimental results show that it is efficient to make the conbination between ICCP techniqe and SS method based on the application of dual functional material and cementitious adhesive material. Larger anode current density(400 mA/m2) can cause serious polarization at the system interface and the smaller the anode current density(26 mA/m2 and 80 mA/m2) can keep the system stable operation for a long time. At the same time, it will not cause interface phenomenon of acidification, after 2 months of impressed current cathodic protection.3) Recycling of carbon fibers using electrochemical method. In this research, we proposed an electrochemical method for the recycling of carbon fibers from CFRP. Experiments were designed with different solution concentrations(3%, 10%, and 20% NaCl) and various levels of applied current(4mA, 10 mA, 20 mA, and 25mA) to identify the significant parameters that affect carbon fiber recycling efficiency. The recycled carbon fibers were characterized by using the single fiber tensile strength test, SEM, XRD, and XPS techniques. Test results showed that the recycling of carbon fibers with electrochemical method is simple, effective, and economical. From the experimental results, the maximum tensile strength of the reclaimed carbon fibers was 80% of the virgin carbon fibers(VCF). The increase in electrolyte concentration did not improve the recycling efficiency but resulted in severe oxidation and chlorination on the surface of recycled carbon fibers.