Investigation of Physical Properties of Graphene-Cement Composite for Structural Applications

Abstract

The hydration of cement generates heat due to the exothermic nature of the hydration process. Poor heat dissipation in mass concrete results in a temperature gradient between the inner core and the outer surface of the element. High temperature gradients generate tensile stresses that may exceed the tensile strength of concrete thus leading to thermal cracking. The present paper is an attempt to understand the thermal (heat sink property) and microstructural changes in the hydrated graphene-Portland cement composites. Thermal diffusivity and electrical conductivity of the hydrated graphene-cement composite were measured at various graphene to cement ratios. The mass-volume method was implemented to measure the density of the hydrated graphene-cement composite. Particle size distribution of Portland cement was measured by using a laser scattering particle size analyzer. Heat of hydration of Portland cement was assessed by using a TAMAIR isothermal conduction calorimeter. Scanning electron microscopy (SEM) was implemented to study microstructural changes of the hydrated graphene-cement composites. The mineralogy of graphene-cement and the hydrated graphene-cement composites was investigated by using X-ray diffraction. The findings indicate that incorporation of graphene enhances the thermal properties of the hydrated cement indicating a potential for reduction in early age thermal cracking and durability improvement of the concrete structures.

Investigation of the effects of graphene and graphene oxide nanoplatelets on the micro- and macro-properties of cementitious materials

“…Based on the XRD and SEM tests, they speculated that the intrinsic reinforcement mechanism was that the hydration gels reacted preferentially with the functional groups on the surfaces of GONPs. In addition, the unique 2D sheet-like structure of GONPs was found to form a barrier against crack propagation so as to provide a 2D isotropic reinforcement for cement paste [14]. This is an advantage over the nanofiber-like additives, which strengthen concrete microstructure only normal to their longitudinal direction, and thus cannot arrest the microcrack growth parallel to it.…”

“…Graphene nanoplatelets (GNPs) and graphene oxide nanoplatelets (GONPs) are new types of nano-particles consisting of graphene stacks [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Different from pristine graphene, GONPs are oxides of GNPs, and thus contain the functional groups attained during oxidation and exfoliation process.…”

“…In addition, by enhancing the packing density of calcium-silica-hydrate (C-S-H), some nano-sized additives can effectively reduce the microstructure porosity, and thus greatly decelerate the transport rate of the deleterious agents in concrete. Therefore, despite certain challenges existing in dispersion, bonding and cost [1,14], incorporation of nano-sized additives in concrete is showing great potentials for producing stronger and more durable construction materials.…”

Graphene nanoplatelet-fly ash based geopolymer composites

“…All of the graphenereinforced ceramic matrix composites were found to exhibit a decreased tendency to fracture, mainly because of crack bridging, crack deflection, crack tip shielding, and crack branching. Moreover, few studies have investigated the effect of graphene on the properties of cementitious materials [25][26][27][28]. Lv et al reported that the addition of 0.3% of graphene oxide in cement composites showed a remarkable increase of 78.6%, 60.7% and 38.9% in tensile strength, flexural strength and compressive strength, respectively [25,28].…”

Application of Nanomaterials in Production of Self-Sensing Concretes: Contemporary Developments and Prospects

“…Besides the proper dispersing method, preparation of new functional fillers or hybrid fillers can contribute to the development in this field of science. In the last years graphene oxide [23,24] and graphene nanoplatelet [15,25] have gathered spectacular attention as a potential material to improve self-sensing ability of cement-based materials. The entanglement of carbon nanotubes represent some major challenge for large-scale structural application.…”