Effect of excessive fiber reinforcement on mechanical properties of chopped glass fiber reinforced polymer concretes

Polymer concretes (PCs) have evolved with the growing need for special concretes in the construction sector such as swimming pools, sewer structures, drainage channels, reinforcement injection, and other structures that contain liquids or corrosive chemicals. Recently, these concretes have been prioritized and their importance is growing. In this study, chopped glass fiber (CGF) reinforced polymer concretes (CGFRPCs) are emphasized and the effect of excessive fiber reinforcement on the mechanical properties of concrete is investigated. In this regard, six different mixtures; M1 (Pure PC), M2 (0.15 % CGFs), M3 (0.20 % CGFs), M4 (0.25 % CGFs), M5 (0.50 % CGFs), M6 (1.0 % CGFs); were prepared by considering 0, 0.6, 0.8, 1, 2 and 4 reinforcing indexes (RIs) with a constant aspect ratio (6/0.015 = 400), respectively. Then, the initial setting time, final setting time, peak temperature and flow tests are performed on the fresh concrete samples. The density, flexural strength and compressive strength at 7, 14, 21 and 28 days are determined on the prism and cube samples as the hardened concrete tests. Besides, scanning electron microscope (SEM) examinations are performed to obtain detailed information about the behavior of the concretes. The experimental studies and SEM evaluations show that excessive fiber reinforcement negatively affects both fresh concrete properties and hardened concrete properties because of fiber agglomeration, thixotropy, fiber pull-out, fiber breakage, dislodged aggregate, interface and matrix cracks. In addition, it is observed that the problems observed in the CFRPCs increase as the RI increases.