Facile synthesis of novel dopamine-modified glass fibers for improving alkali resistance of fibers and flexural strength of fiber-reinforced cement

Glass fiber-reinforced cementitious material is one of the significant components in structural materials playing vital roles in enhancing the tensile and flexural behavior of cement-based quasi-brittle materials. Compared with carbon and polymer fibers, its intrinsic similar silicate-based composition to cement was endowed with better bonding properties and compatibility with cement-based materials. However, the poor alkali resistance of glass fibers restrained their potential development for spreading to applications in construction fields. In this study, dopamine-modified glass fibers (DP) were self-polymerized at ambient temperature by a facile method for enhancing the alkali resistance of glass fibers. Scanning electron microscopy and X-ray photoelectron spectroscopy were utilized for characterizing DP. The duration of reaction and fiber to solution ratio were adjusted with an optimal reaction time of 12 h and fiber to solution ratio of 0.12 g ml−1 acquired. Alkali resistance was measured by strength retention tests in both mortar and sodium hydroxide solution. Compared with untreated glass fibers (UN), DP exhibited a distinct improvement in strength retention rate of 37.1% and 18.9% under mortar and sodium hydroxide solution environments, respectively. Also, flexural strength tests of DP-reinforced cement were conducted, and its strength was increased in comparison with that of UN-reinforced cement by 58.2%. As a consequence, a novel simple method for improving the alkali resistance of glass fibers was proposed and is anticipated to promote the development and applications of glass-fiber reinforced cement-based materials.