Mechanical properties and microstructure of glass fiber and polypropylene fiber reinforced concrete: An experimental study

This paper presents the results of a comprehensive experimental work investigating the effect of glass fiber (GF) and polypropylene fiber (PPF) on the mechanical and microstructural properties of concrete as a function of the water/binder ratio and fiber content. Different water/binder ratios (0.30 and 0.35), GF and PPF contents (0.45, 0.90, and 1.35% by volume fractions), and curing times (7 and 28 d) were used during the experiment to prepare the concrete specimens. The compressive, four-point flexural, and splitting tensile strengths and the full curves of water absorption of the glass-fiber-reinforced concrete (GFRC) and polypropylene-fiber-reinforced concrete (PPFRC) were obtained. The strength differences and water absorption properties of GFRC/PPFRC were analyzed in depth. Scanning electron microscope observation was undertaken to analyze the mechanism of the water/binder ratio and fiber effects. The results showed that the water/binder ratio can affect the optimal fiber content. When discussing the effect of fibers on the improvement of concrete mechanical or microstructural properties, the influence of the water/binder ratio should be considered. The improvement effect of GF on water absorption was significantly superior to that of PPF. When the water/binder ratio was 0.30, the water absorption of GFRC and PPFRC tended to be stable as the test proceeded, while when the water/binder ratio increased to 0.35, the water absorption of the GFRC and PPFRC with the highest fiber dosage still increased with the prolongation of testing time. (C) 2020 Elsevier Ltd. All rights reserved.