PSI - Issue 52

Sairam Neridu et al. / Procedia Structural Integrity 52 (2024) 267–279 Sairam Neridu/ Structural Integrity Procedia 00 (2019) 000 – 000

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poor-quality concrete, which can affect UPV test results. Inadequate mixing can result in voids, cracks, and other defects that can interfere with the transmission of ultrasonic waves. If low-quality materials are used, they can lead to poor-quality concrete, resulting in lower UPV values. Structural defects such as cracks or voids can also affect UPV test results in new concrete bridges.

Table 2. Shows Observations of Ultrasonic Pulse Velocity test.

Path Thickness (mm)

Pulse Velocity (km/sec)

Corrected Pulse Velocity (km/sec)

Concrete Quality As per Referred Table – II

Sl. No.

Member Id*

Test Method

Location

0.4m from the RHS end and 1.15m from Raft 3.35m from the RHS end and 0.9m from Raft 6.3m from the LHS end and 2m from Raft 4.3m from the LHS end and 0.7m from Raft 4.2m from the RHS end and 1.95m from Raft

Doubtful

Direct

300

3.700

3.700

1 Wall pier

Poor

Indirect

400

2.203

2.202

2 Wall pier

Poor

Indirect

400

2.353

2.353

3 Wall pier

Good

4 Wall pier

Indirect

400

3.704

4.204

Good

5 Wall pier

Indirect

400

3.401

3.901

Table 3 shows the results of the Rebound Hammer test conducted on five different locations (members) on the pier wall. The Rebound Hammer test is a non-destructive testing method that measures the rebound of a spring-loaded hammer after it impacts the concrete surface to determine the strength and quality of the concrete. The corrected rebound number is obtained by considering the effect of surface roughness, moisture, and other factors on the rebound number. The estimated compressive strength of the concrete is then calculated based on the corrected rebound number using a reference chart.

Table 3. Shows Observations of the Rebound Hammer test.

Corrected Rebound Number

Estimated Compressive Strength (N/mm²)

Sl. No

Member

Location ID

Method

Rebound Numbers

0.4m from the RHS end and 1.15m from Raft

1 Pier wall

Horizontal

39.5,42,42.5,44.5,43,48

43.3

34.14

3.35m from the RHS end and 0.9m from Raft

Horizontal

43,43,48,41.5,41,49

44.3

35.37

2 Pier wall

6.3m from the LHS end and 2m from Raft

3 Pier wall

Horizontal

54,44,39.5,44.5,46.5,47.5

46.0

37.63

4.3m from the LHS end and 0.7m from Raft 4.2m from the RHS end and 1.95m from Raft

4 Pier wall

Horizontal

56,51.5,56,54,50.5,55

54.8

51.44

Horizontal

47,45.5,45.5,43.5,54,43.5

46.5

38.30

5 Pier wall

The results of the Rebound Hammer test demonstrate that there are variations in the estimated compressive strength of the concrete among the different members of the pier wall. Members 1, 2, and 3 exhibit lower estimated compressive strength values ranging from 34.14 to 37.63 N/mm², while members 4 and 5 display higher estimated compressive strength values ranging from 38.30 to 51.44 N/mm². The quality of the concrete surface finishing can also contribute to higher rebound hammer test strength. A smooth and level surface can enhance the bond between the concrete and