PSI - Issue 68

Asad Zia et al. / Procedia Structural Integrity 68 (2025) 231–237 A. Zia et al. / Structural Integrity Procedia 00 (2025) 000–000

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strength testing. The tests were conducted using 100 mm cubes for water absorption and cylindrical specimens for split tensile strength and compression tests. Typically, two to three readings were averaged for each property, with specimens tested at 28 days old. 3. Analysis of Test Results 3.1. Water Absorption Test Results Water absorption is a critical parameter for assessing the durability and pore connectivity of concrete, serving as an indirect measure of its permeability. The immersion-based method, as prescribed by ASTM C642-13 and Belgian Code NBN B15-215, is widely regarded as an effective approach for determining water absorption (WA) in concrete (De Schutter & Audenaert, 2004). The results obtained from WA tests are presented in Table 1. Specifically, water absorption values of 2.20%, 1.94%, and 2.12% were observed for plain concrete (PC), 6EF7R, and 6IS7R, respectively. These values are also illustrated through a percentage comparison in Figure 1.

Table 1 Test results of water absorption

0F7R 2.20 0.08

6IS7R

6EF7R

Water absorption (%) Standard deviation (%)

1.94 0.20

2.12 0.01

Figure 1 Water absorption test results

The inclusion of industrial steel fibers in RAC resulted in a 12% reduction in water absorption compared to plain concrete, while the addition of 0.60% waste tire steel fibers (EFs) led to a 3% reduction. This improvement is likely due to the fibers' ability to restrict water movement within the concrete matrix, thereby reducing the ingress of water. Consequently, the fibers exhibit a synergistic effect, where the combined use of industrial steel fibers and recycled tire steel fibers enhances water absorption resistance more effectively than plain concrete. Therefore, incorporating both industrial hook-end steel fibers and recycled waste tire steel fibers holds the potential for significantly improving concrete durability by reducing its permeability to water and minerals over time. 3.2. Compressive Test Results The compressive strength test results are presented in Table 2. The plain concrete with 75% RCA (0F7R) exhibited a compressive strength of 30.46 MPa, while the steel fiber-reinforced concretes, 6IS7R and 6EF7R, demonstrated slightly lower values of 30.40 MPa and 30.03 MPa, respectively. The reduction in compressive strength for 6IS7R and