| 主权项 |
1. A method for real-time and in-situ monitoring the freeze-thaw damage of concrete, including the following steps:
(1)—embed pairs of gradient electrical resistance probes into a surface of the concrete at the depth of 0˜50 mm, each of the pairs of gradient electrical resistance probes comprising an anti-corrosion metal bar, the buried depth gradient between different pairs of electrical resistance probes being in the range of 1 mm to 20 mm, and the buried depth gradient of the pair of electrical resistance probes nearest to the surface being less than 5 mm; (2)—transmit the impedance value of the concrete measured by each of the pairs of gradient electrical resistance probes to a monitor center for processing; (3)—evaluate a spalling status of freeze-thaw damage to the concrete based on changes in impedance value as reflected in a curve of impedance versus time, there being two evaluation standards according to conditions: (A). The electrical resistance probes with a same depth meet with abrupt changes for the concrete impedance value and there are three statuses:
i. on the curve of Impedance-Time, an impedance value changes from relatively stable to infinite at the moment the concrete suffers spalling and free water does not penetrate the concrete;ii. on the curve of Impedance-Time, the impedance value changes from relatively stable to almost zero at the moment the concrete suffers spalling and free water penetrates into the concrete;iii. on the curve of Impedance-Time, where the impedance value presents a vertical change in trend: if the impedance value rises, the concrete suffers spalling and free water does not penetrate the concrete, whereas if the impedance value decreases, it suffers spalling and free water penetrates into the concrete; and (B). From the surface to the interior, for each pair of buried electrical resistance probes at each layer, if the impedance value of the concrete meets with the status as mentioned in A, refer to A and judge according to the standards discussed in A. |
