This paper summarizes the relationship between the cover-zone mortar resistance (Rs) and the Rp of the steel anodes, and aims to predict Rp from the Rs values of the surrounding cover mortar using the parameters obtained from the developed sensors, instead of directly measuring the Rp of so the structural steel.2.?Experimental2.1. MaterialsP?O 42.5 cement from Harbin Cement Co. LTD was used for all experiments in this study. River sand with a fineness modulus of 2.4 was used as a fine aggregate. The chemical composition of the steel anodes used for the sensor, corresponding to Q235 steel, is given in Table Inhibitors,Modulators,Libraries 1. Q235 steel is widely used in civil engineering and especially in coastal constructions in China.Table 1.Chemical composition of the steel anodes used in this study.2.2.

Sensor ArrangementsFigure 1 presents a photo and a detailed schematic of the corrosion sensor embedded in cement mortar. Each of Inhibitors,Modulators,Libraries the four differently-sized steel anode rings was fixed on a fabricated nylon tower [see Figure 1 (b)], spaced Inhibitors,Modulators,Libraries 10 mm from one another. The detailed geometrical design of each steel anode is given in Table 2. Cables connected to each single steel anode, S1~S4, were run out of the cover-zone mortar.Figure 1.(a) Photo of the embeddable corrosion sensor. (b) Schematic of the placement of the corrosion sensor in cement mortar.Table 2.The geometrical sizes of the steel anode rings used in this study (mm).This geometrical sensor design ensures that:Each steel anode has an equal exposure area of about 668 mm2.

The surface area of the cathode (more than 3,000 mm2) is sufficiently larger than the anodes to reduce errors due to the lateral current distribution on the surface of Inhibitors,Modulators,Libraries the steel anodes [21].The cement mortar cover over each steel anode is not affected by the parts of the sensor, thus, the penetration of chloride into each Carfilzomib anode and the carbonation of the surrounding cement mortar are not influenced by the adjacent anodes.The sensors can be used in existing concrete structures by inserting them into holes drilled in cover-zone concrete. Furthermore, all of the measured parameters are depth-related. In this way, the penetration of chloride and/or carbonation from the cement mortar surface into the cement mortar and the subsequent corrosion risk of the reinforcing structures can be measured immediately.

A cathode made of Ti/MMO (mixed metal oxide-coated titanium), which is widely used in the cathodic despite protection system, was placed 10 mm above anode S4. A fabricated long-term Ti/MnO2 reference electrode (RE) was embedded adjacent to the corrosion sensor for potential measurements, and the stable potential of the RE is ?40 �� 5 mV referenced to the saturated calomel electrode (SCE) [18]. Each sensor was embedded in the middle of a cubic cement mortar specimen (10 cm �� 10 cm �� 10 cm). The distance between the upper end of the sensor and the upper surface of the cement mortar was 2 mm.2.3.