Each bond–slip curve of uncorroded

Each bond–slip curve of uncorroded specimens consists of three segments, namely, ascending segment, approximate horizontal segment, and descending segment. The slip corresponding to the approximate horizontal segment accounts for the vast majority of the total slip (specimen B2.2 is an exception because of experimental discreteness). However, each bond–slip curve of the corroded specimens consists of only two segments – ascending and descending – and the gradient of the descending segment increases with the severity of the corrosion.The pull-out process after the cementation action is destroyed works for the corrosion-free strands with sufficient screwing effect because of the smooth and unbroken regular spiral ribs. Thus, the approximate horizontal segment is formed and remains until the split crack increases to a width too wide to maintain holding function. However, the original regular spiral ribs for the corroded strands are broken. This damage weakens the screwing effect, and so the pull-out process after cementation action is destroyed works mainly with gear action. Thus, the descending segment is formed directly after the ascending segment with no transition by approximate horizontal segment.