PSI - Issue 70

R. Ashwathi et al. / Procedia Structural Integrity 70 (2025) 183–190

186

3. Results and discussion: The fresh properties were primarily evaluated through slump test as per IS 1199:1959 and concrete specimens were casted under controlled conditions using binary blind of steel and polyester fibres as per IS codes (IS 516:1959 and IS 5816: 1999). The testing was performed using calibrated Universal Testing Machine under standard loading.

3.1 Compressive Strength:

Compressive strength is employed as one of the vital parameters in evaluating effective performance of the fibre incorporated into the matrix (Cao Mehran, 2020). The capability to withstand the axial load relies on the type of fibre, its proportion, mix and the age of curing. The compressive strength results are displayed in the Table 4.

Table 4. Compressive Strength of concrete Specimen % added

7 Day (MPa) 20.32 24.24 21.42 21.26 21.92

14 Day (MPa)

28 Day (MPa)

7 Day (MPa) 30.12 28.12 26.41 30.12 27.62

14 Day (MPa)

28 Day (MPa)

Specimen

% added

CC

0

28.12 34.96 31.27 30.10 31.72

31.24 37.74 33.64 32.24 35.26

SFRC SFRC HFRC HFRC HFRC

0.5

40.24 38.16 36.26 41.12 40.12

44.64 42.92 40.64 45.62 44.44

PFRC PFRC PFRC SFRC

0.25

0.75

0.5

0.25 - 0.75

0.75 0.25

0.5 - 0.5

0.75 - 0.25

Fig. 1. Compressive Strength of concrete The conventional concrete shows a steady incline in Fig.1. over ages and serves as a baseline for interpretation. The addition of fibre enhances strength of concrete, particularly hybrid inclusion delivers enhanced outcome owing to its complementary properties of toughness and crack resistance. Excessive percentage of fibre individually does not contribute greatly to strength while hybrid incorporation does which may be due to clamping of fibres together causing uneven distribution and makes the zone weaker (Haripriya and Ganesh Naidu, 2023) (Shirsath Subhash C., 2017). The percentage increase tends to range between 2.65% and 17.22% and 10.65% and 38.90% for PFRC and SFRC. The percentage increase tends to range between 24.91% and 34.98% highlighting the combined effect of PFRC and SFRC. The steel and polyester fibres incorporated in the ratio of 0.5-0.5 exhibits highest performance among various mixes.

3.2 Split Tensile Strength:

Concrete inherently weak in tension due to the interfacial transition zone which causes the cracks to propagate through it could gain benefit by adding fibres to the matrix (Baldenebro-Lopez, 2014; Park Dong Joo; Ryu, Gum Sung; Koh, Kyung-Taek, 2012). The inclusion of fibres enhances the tensile strength by providing resistance to cracking and ductility of the structure by bridging the cracks developed under tension (Frazão Joaquim A. O.; Bogas, J. Alexandre; García-Cortés, Verónica; Valente, Tiago, 2022). The tensile strength results are displayed in Table 5.