Étude multiéchelle de l’efficacité de l’oxyde de graphène dans les matériaux à base de ciment

Abstract

This study was conducted to evaluate the impact of a small percentage (0.03%) of graphene oxide (GO) on the properties of cement-based materials. Derived from graphene, this nanomaterial consists of hexagonal arrangements of carbon atoms with several functional groups in its structure such as hydroxyl, epoxy, carboxyl and carbonyl. The growing interest in nanomaterials has led several researchers to consider the use of this new generation of materials to improve the performance of concrete. Thus, through an experimental program based on a multiscale characterization, the impact of GO on the performance of cementitious matrices has been evaluated. The GO dispersion method (superplasticizers and sonication), the W/B ratio (0.35 and 0.40) and the use of binary binders, one made of 30% blast furnace slag and the other with 8% of silica fume, were also variables that have been studied. To make this technology potentially accessible to concrete producers, commercially available GO was used for the trials. Through isothermal calorimetry and thermogravimetric analysis (TGA) tests, it was possible to characterize the hydration reaction of the GO modified cementitious materials. It turns out that the effect of GO is visible on the heat release rate curves, especially when dispersed by superplasticizer and by a combination of superplasticizer and sonication. This effect, on the general use cement (GU) and on the binary binder, is mainly noted on the amplitude of the calcium aluminate (C3A) peak. This observed change in the second hydration peak shape can be attributed to the nanofiller phenomenon provided by the GO. The TGA tests did not show that the use of GO affected the hydration products of the cement at 3, 7 and 28 days. Next, compressive strength tests were used to evaluate the mechanical strength of mortar at 1, 7, and 28 days. The first result is that the addition of GO to the mixes significantly reduces the flow of the mortar in the fresh state. A decrease in compressive strength is also noted for mortars without superplasticizer. The results finally show that no benefit on compressive strength is obtained from the use of GO. To evaluate the effect of GO from a practical application point of view, chloride ion penetration tests were carried out at 28, 56, and 91 days, on concretes based on the Ministère des Transports (MTQ) and Canadian standard association (CSA) VS/C-1 and XIII/C-XL mixes. The results showed that GO reduces the penetration of chloride ions by between 5.5 and 24.9%, depending on the cure period and the type of concrete mix. However, mixes modified with GO do not meet the 1000-coulomb requirement of MTQ standard 3102. Concretes with silica fume showed far superior results. Thus, graphene oxide must be used in other environmental conditions and would be better in other mix design.

Date	10 Apr 2023
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Claudiane Ouellet-Plamondon (Supervisor)