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Despite being most widely used construction materials, cement-based composites are brittle materials with low tensile strength and susceptible to cracking, especially under harsh environments. Over the past three decades, numerous studies have been conducted to enhance the mechanical properties and durability of cementitious composites through the use of various nanomaterials such as carbon nanotubes (CNTs) and carbon nanofibers (CNFs). More recently, graphene nanoplatelets (GNPs) has emerged as an ideal 2D nano-reinforcement for composite materials due to their favorable mechanical, thermal and electrical properties. However, the effects of different dispersing agents and particle size and surface area of GNPs on the mechanical properties of cement-based composites needs to be further investigated. This paper explores the influence of GNP addition on the mechanical properties and durability of cement-based composites. Two types of GNPs with different lateral size (<2 μm and 25 μm) and specific surface area (300 m2/g and 120 m2/g) are used in this study. The GNP concentration is set to be 0.1% by weight of cement in all mixtures. In order to study the effect of dispersion agents, four different dispersion method are utilized to disperse and stabilize GNP particles in aqueous solution. Compressive strength and flexural strength tests are conducted to assess the mechanical properties, while sorptivity test and surface resistivity measurement are carried out to evaluate the durability. In order to explore the effect of GNPs on hydration process of cement mortar, mechanical properties tests are conducted at 7 day and 28 day curing ages and thermal gravimetric analyses are conducted.
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