PSI - Issue 60

Harikrishna S et al. / Procedia Structural Integrity 60 (2024) 700–708 Harikrishna S / Structural Integrity Procedia 00 (2019) 000–000

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4.0 Non-Destructive Evaluation To ascertain the damage properly, NDE was carried out on concrete distress locations of wall using in-situ Non destructive techniques (NDT) like Ultrasonic Pulse velocity test (USPV), Rebound Hammer test (RH), Half-cell potentiometer tests (HCP) etc. The results of tests obtained also confirmed that the concrete quality was poor on middle portion of wall. The NDT report results indicated that concrete on top portion on South side of wall is also fully damaged. The extent of damage was in range of around 60% of area of wall. It was decided that repair jobs shall be carried out on middle wall.

Fig. 9. Damage representation of middle wall

At many distress locations, the core samples could not be collected as the machine could not be mounted to surface. So, core samples were limited to 2 locations on bottom portion of wall where reasonable strength was there for concrete and could support the core cutter machine. The cores were observed to have yellow patches on inner surface confirming sulphur intrusion inside wall.

Fig. 10. Core samples

4.1 RESULTS OF NDE a. Rebound Hammer test: - The results obtained were less than 10 MPa at distress locations. b. Ultrasonic Pulse velocity test: - The concrete quality was inferred to be Poor. c. Half Cell Potential test: The Probability of corrosion is greater than 90% (Severe). d. Core test: - depth of carbonation of extracted concrete core sample is varying from 55 to 80 mm. The above results confirmed the condition of concrete.

Table 1: results showing depth of carbonation.

5.0 Inferences