Maintenance and repair of steel reinforced concrete structures by simultaneous galvanic corrosion protection and chloride extraction

摘要

A novel galvanic zinc anode system, composed of a zinc mesh embedded into a proprietary binder that solidifies into a solid matrix with ion exchange properties, was developed by CAS. The solid matrix of the embedded zinc anode system (EZA) is based on a tecto-alumosilicate-binder containing additives that prevent passivation of the zinc anode, assure high and durable galvanic activity of the zinc anode and high and durable adhesion towards the concrete overlay. The efficiency of the galvanic corrosion protection (GCP) of the steel reinforcement with a novel embedded zinc anode (EZA) is evaluated on four types of civil structures - abutment of a road bridge in the Styrian Alps in Austria, concrete abutments of a steel bridge and support-beams for the bearings of four viaducts in the Netherlands and a parking deck in Switzerland. The efficiency of the GCP was monitored with embedded reference cells, concrete resistivity - and macro cell sensors. Data collected over a period of more than 6 years show that the EZA protects the steel reinforcement efficiently and reliably. Based on these data, estimation of expected service time is discussed. Data indicate an efficient migration of chloride ions towards the anode and their chemical immobilization in the binder matrix.