PSI - Issue 18

Sana Gul et al. / Procedia Structural Integrity 18 (2019) 101–107 Sana Gul/ Structural Integrity Procedia 00 (2019) 000–000

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concrete mix. After mixing, the cylindrical molds were filled in layers being placed on vibrating table for proper compaction and to remove the air entrapped in voids. 4. Testing Procedures 4.1. Compressive Strength Test Cylindrical specimens of dimension 6 in x 12 in were tested according to ASTM C 39 test standard 12 . To keep the load uniform and distributed, cylinders were capped with sulfur mortar (ASTM C 617). Sulfur caps were applied two hours before testing. The loading rate on a hydraulic machine were kept in range of 20 to 50 psi/s . 4.2. Split Tensile Strength Test For split tensile strength, the samples were tested according to ASTM C 496-96 13 . The specimens were placed in Universal Testing Machine (UTM) along the length. In this test a diametral compressive force were applied along the length of the cylindrical specimen at a given rate un till failure occurs. 5. Results and Discussion 5.1. Compressive strength test From Figure 4 it can be seen that compressive strength reduced up to 20% and 38% for 1% and 5% incorporation of RRSF as compared to the specimens containing SF respectively. Specimens containing recycled rubber steel fiber (RRSF) showed notable ductility before failure under compression loading. Horizontal cracks were observed for RRSF specimens. This reduced compressive and flexural strength for RRSF might be because of improper bonding between the cement particles and RRSF as compared to cement and SF 14,15 . This might lead to the non-uniformity of the applied load. The compressive strength of concrete depends on the bond between cement, aggregate and the fibers use 11 . In case of RRSF this bond seems to be weak that is why the strength degradation occurred for the specimens containing RRSF.

1% SF and RRSF 5% SF and RRSF

0 10 20 30 40 50 60

Compressive Strength (MPa)

SF

RRSF

Fig. 3. Compressive Strength Test Results

5.2. Split Tensile Strength Test From figure 5 it can be seen that the split tensile strength tests up to 14% and 42 % reduction of strength were observed for 1% and 5% replacement of RRSF respectively. The percentage reduction of split tensile strength was