The effects of various formwork surfaces on the corrosion performance of reinforcing steel in concrete

摘要

In this study, the effects of various formwork surfaces on the corrosion performance of reinforcing steel in concrete were examined. For this purpose, seven formwork surfaces from populus nigra, pinus silvestris, steel sheet, and four of plywoods were prepared. Three of the plywood formworks were covered with different geotextile liners and drainage channel and holes were drilled on their surfaces. One of the plywood formworks having no processes on its surface was for control. Reinforcing steels were first embedded in formworks and then the concrete was poured. The samples were exposed to corrosion in a way of settling them in 5% NaCl solution. We tested the corrosion potential and bonding strength of the samples. Later, the mass loss and tensile strength were measured on reinforcing bars that were pulled out from the concrete. The chloride content and pH values were also tested on concrete powders. The results indicated that drained-lined formwork (F5 with TB50 + F613 geotextile liner) compared to steel sheet (F4 undrained and unlined) gave 16% lower corrosion and 68% higher bonding strength on reinforcing bars embedded samples, 73% lower mass loss and 4% higher tensile strength on reinforcing bars, and 70% lower chloride content and 4% higher pH on concrete powders. In addition, it was found that the corrosion strength of reinforcing steels in concrete could be increased if drained-lined formworks were utilized.