Analisis Pengaruh Variasi Persentase Serat Fiberglass Terhadap Kuat Tekan dan Kuat Lentur Beton 24 22

Abstrak

Concrete is one of the most widely used construction materials due to its high compressive strength. However, concrete is inherently brittle, resulting in relatively low resistance to tensile and flexural forces. One approach to improving its mechanical performance is the incorporation of fiberglass fibers as an additive and the use of fly ash as a partial cement replacement. This study aims to analyze the effect of fiberglass fiber addition on the compressive and flexural strength of concrete, evaluate the influence of different percentages of fiberglass fibers on these mechanical properties, and determine the optimum fiberglass fiber content. This research employed an experimental laboratory method using concrete with a design compressive strength of 19 MPa. Fly ash was used as a 15% partial replacement for cement, while fiberglass fibers were added at proportions of 0% (normal concrete), 0.75%, and 1.75% by the weight of cement. Cylindrical specimens were prepared for compressive strength testing, while beam specimens were used for flexural strength testing. All specimens were cured for 28 days before being tested in accordance with the applicable standards. The results indicate that the addition of fiberglass fibers and fly ash significantly affects the mechanical properties of concrete. The mixture containing 0.75% fiberglass fibers increased the compressive strength from 20.36 MPa to 22.90 MPa and the flexural strength from 3.33 MPa to 4.12 MPa. In contrast, the mixture containing 1.75% fiberglass fibers reduced the compressive strength to 19.61 MPa due to decreased workability and the occurrence of fiber balling, although the flexural strength continued to increase to 4.64 MPa. Based on these findings, the use of 0.75% fiberglass fibers with a 15% fly ash substitution is considered the optimum mixture because it improves both compressive and flexural strength without significantly reducing the workability of the concrete.

Keywords: concrete, fiberglass fibers, fly ash, compressive strength, flexural strength.