PSI - Issue 47

Shakiba Zolfaghari et al. / Procedia Structural Integrity 47 (2023) 398–407 S. Zolfaghari et al./ Structural Integrity Procedia 00 (2019) 000–000

401

4

Sikadur-330 was used to impregnate the fibers with adhesive and bond the sheet to the concrete and fill the 2.5 mm wide grooves. The single-lap shear tests were performed as displacement-controlled test at a loading rate of 2 mm/min according to the ASTM D3039/D3039M-17.

Table 2. Material specifications

Flexural Modulus of Elasticity (GPa)

Tensile Modulus of Elasticity (GPa)

Elongation at Break (%)

Tensile Strength (MPa)

Flexural Strength (MPa)

Compressive Strength (MPa)

Thickness (mm)

Sikadur-31 Sikadur-330

- -

15-20

30-40

60-70

4.3 4.5 230

-

-

30

- -

- -

3.8

0.9 1.5

SikaWrap-300 C

0.17

3900

-

3. Experimental results and discussion In Table 1, the maximum load and the debonding load for EBR and EBROG specimens are included. The debonding load or the load corresponding to the starting point of sheet separation from concrete is the level of the load that, with the continuation of the loading process after that, the longitudinal shear stress profile (i.e., the stress diagram along the length of the FRP-concrete bond) experiences the zero stress value at the beginning of the connection. In many studies, the maximum load that can be tolerated by the joint is referred to as the bond strength. If this definition is applied, the following results can be obtained from the above tests: By digging only one longitudinal groove on the concrete surface, the maximum load supported by the connection was 14.7 to 73.5% higher than the maximum load of EBR (Table 1). Among all the specimens, the specimen EBROG-10×5 (with a groove width of 10 mm and a groove depth of 5 mm) with a maximum load of 14.40 kN performed best and is considered as the specimen with the optimal groove dimensions.

Table 3. Maximum load tolerated by the FRP-concrete joint in kilonewtons for different dimensions of the groove.

2.5

5

10

15

b g (mm)

h g (mm)

2.5

9.85

-

-

-

5

10.78

11.09

14.4

12.86

7.5

9.52

-

-

-

10 15

- -

12.66 11.28

10.75 10.74

12.08

13.5

(b g : groove width; h g : groove depth)

At the groove depth of 5 mm (groove widths of 2.5, 5, 10, and 15 mm), with the increase of the groove width from 2.5 to 10 mm, the bond maximum load increased from 10.78 to 14.4 kN and then by increasing the groove width to 15 mm, it decreased to 12.78 kN. That is, the optimum groove width corresponding to the groove depth of 5 mm is 10 mm (Fig. 1(a) and Table 3). At the groove depth of 10 mm (groove widths of 5, 10, and 15 mm), with the increase of the groove width from 5 to 10 mm, the bond maximum load decreased from 12.66 to 10.75 kN and then by increasing the groove width to 15 mm, it increased to 12.08 kN. That is, the optimum groove width corresponding to the groove depth of 10 mm is 5 mm (Fig. 1(b) and Table 3). At the groove depth of 15 mm (groove widths of 5, 10, and 15 mm), with the increase of the groove width from 5 to 10 mm, the bond maximum load decreased from 11.28 to 10.74 kN and then by increasing the groove width to 15