Issue 65

L. A. Aboul Nour et alii, Frattura ed Integrità Strutturale, 65 (2023) 1-16; DOI: 10.3221/IGF-ESIS.65.01

Figure 8: Cylinders after testing splitting tensile strength; (a) Normal concrete +2% glass fiber. (b) 75% LECA +2% glass fiber. (c) 85% LECA +2% glass fiber. (d) 95% LECA + 2% glass fiber. (e) 75% LECA +1% glass fiber. (f) 75% LECA + 1.5% glass fiber.

Figure 9: Four points loading applied to beam specimens. Fig. 5.g and Fig. 5.h show the relation between tensile strengths, LECA content, and fiber content. Firstly, the splitting tensile strength of normal concrete was 3.395 MPa, which decreased by 53%, 46%, and 40% for 75%, 85%, and 95% LECA mixtures to reach 1.578, 1.815, and 2.02 MPa, respectively. While the splitting tensile strength increased in LECA mixtures with 1% and 1.5% glass fiber, it decreased in LECA mixtures with 2% glass fiber content. Splitting tensile strength increased by 30.5% and 40.5% for 1% and 1.5% fiber content to reach 2.36 MPa and 2.02 MPa, respectively. Secondly, the flexural strength of normal concrete was 22.734 MPa. Using LECA aggregate at rates of 75% and 95% caused a small reduction in flexural strength at rates of 2% and 4% to be 22.236 and 21.802 MPa, respectively. While using LECA aggregate at a rate of 85% achieved flexural strength more than normal concrete by about 7.5%. At the same time using 1.5% and 1% fiber content increased flexural strength by rates of 7% and 0.9% to reach 24.245 and 22.937 MPa, respectively, compared to 22.236 MPa for LECA concrete with 2% fiber content. Amani et al. mentioned that the increased strength of LECA concrete directly depends on the content, length, and thickness of the used fiber. Glass and Polyolefin fiber enhance the flexural strength of LECA concrete by around 18% and 45%, respectively [16]. This finding is consistent with that of the current study. Fig. 10 shows that all concrete samples had a splitting tensile to compressive strength ratio in the 5-10% range. When compared to normal concrete, using LECA and glass fiber increased the ratio between splitting tensile strength and compressive strength by about 42% and 13% for samples L75-F1 and L95, respectively. The concrete with 75% LECA content + 1% glass fiber (L75-F1) had the highest splitting tensile to compressive strength ratio of 10%. While the concrete

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