Beam specimens of polypropylene fiber-reinforced concrete (PPFRC) with 1.3 vol. % having three different sizes, 100 x 100 x 400 mm, 150 x 150 x 530 mm, and 200 x 200 x 650 mm, were tested under four-point bending tests to investigate the flexural behavior (flexural and post-cracking strengths). The beam specimens were quarried from PPFRC slabs to evaluate the influence of the fiber orientation and distribution and the concrete casting and loading directions on the flexural behavior. The test results show that the difference in the fabrication methods of specimens considerably affected the flexural behavior. The flexural cracking strength was accompanied by the size effect and the post-cracking strength, significantly decreased when compared with standardized prism specimens; however, the post-cracking strength was not sensitive to the size effect. Furthermore, the pavement thickness of PPFRC was compared with that of plain concrete with the calculation using the post-cracking strength.