Study on dispersion, mechanical and microstructure properties of cement paste incorporating graphene sheets

In this study, the influences of ultrasonic and surfactants on the dispersion of graphene sheets in water were evaluated using UV-vis spectroscopy, and homogenous dispersions of graphene sheets in water were obtained by using sodium dodecyl benzene sulfonate (SDBS). Then, the highly dispersed graphene sheets were introduced to cement paste through high-speed mixing, and the mechanical and microstructural properties of graphene-modified cement material was evaluated. Experiment results indicated that the addition of 0.025 wt% graphene sheets increased the 7-day composite compressive strength by 14.9%, the flexural strength by 23.6% and direct tensile strength by 15.2%. X-ray diffraction (XRD) analysis showed that the addition of graphene sheets lowered the orientation index of calcium hydroxide (CH) crystals significantly. Moreover, mercury intrusion porosimetry (MW) and microscope imaging (SEM) indicated that a high degree of dispersion of graphene sheets was achieved, and the two-dimensional graphene sheets promote hydration and suppress the extension process of cracks. (C) 2018 Elsevier Ltd. All rights reserved.