Effects of Chopped Cfrp Fiber on Mechanical Properties of Concrete

Enhancing concrete's mechanical properties has become a prominent field in recent years. Numerous studies investigated the possibility of enhancing the mechanical properties of concrete by adding additive materials. In this study, the effects of Chopped Carbon Fiber Reinforced Polymer (CCFRP) on the mechanical properties of low and normal concrete strength were investigated. Different volume fractions (0%, 0.25%, 0.5%, and 0.75%) of chopped carbon fibers were added to the concrete mix for the 13 MPa and 28 MPa concrete grades and five mix trials were conducted to achieve concrete with 13 MPa and 28 MPa. The ratios (1:1.5:2.5) for the normal strength mix and (1:2.6:4.1) for the low strength mix were chosen. Three tests were conducted to evaluate the effects of chopped CFRP on the mechanical properties of concrete: compressive strength, tensile strength, and flexural strength. A total of 120 pieces were cast, including 24 beams, 48 cubes, and 48 cylinders. The casted cubes were 15 × 15 × 15 cm and the cylinders were 15 cm in diameter and 30 cm in length. Prism beams with a 15 × 15 cm cross-section and a 56 cm length were tested under a single point load. The samples were tested at 7 and 28 days of age, and the sample density was recorded. The results of the 28-day test revealed that adding 0.25% CCFRP increased the compressive strength of low-strength concrete by about 10% and slightly enhanced the compressive strength of normal strength concrete by about 5%. When the dosage of CCFRP was increased, however, compressive strength decreased significantly. On the other hand, adding 0.25% CCFRP to both low and normal strength concrete increased split tensile strength by about 44% for normal strength concrete and 16.6% for low strength concrete. Similar improvements were made in flexural strength when this rate of CCFRP fiber was added to the concrete. As such, this study recommends 0.25% CCFRP fiber as the ideal dosage