Study on the Preparation of Modified Polypropylene Fiber Reinforced Cement-Based Composite

Abstract

The concentrated HNO3 is applied to carry out the surface modification of polypropylene fibers for the preparation of PP fiber reinforced concrete composite. The modification effect of the oxidation reaction is evaluated by the mechanical testing of the PP fiber reinforced concrete composite. The stretching vibration of O-H and C=O bond centered at the wave number of 3300 cm−1 and 1720 cm−1, respectively, indicates the oxygen-containing groups are generates on the surface of the modified polypropylene fiber. The contact angles of the modified polypropylene fiber are also significantly reduced to about 81°, compared with the untreated polypropylene fiber (112°). SEM analysis suggests that the corrosion effect of HNO3 modified polypropylene fiber on the surface is quite obvious since the surface becomes very rough and has grown pore structure near the surface area. Finally, the modification PP fiber reinforced cement composite has an increment of 11.5% on the fracture strength properties compared by the untreated PP fiber. The results indicated that the oxidation process by the concentrated HNO3 could substantially improve the mechanical properties of modified PP fiber in the concrete composite. The reason should be the elevated hydrophilic properties of the modified PP fiber improve the interface bonding strength which is crucial for the performance of the composite.