Efeitos do óxido de grafeno nas propriedades termomecânicas do concreto

Abstract

Since the discovery of cement and the resulting possibility of producingvariouscementitious materials, such as concrete, they have been widely usedincivil construction. As its use is high in civil construction, the need to improvethismaterial is discussed, for example, for application in environments with extreme temperatures.An example of a recent addition is organic carbon nanomaterials (carbonnanotubes,graphene, graphene oxide), which have developed significant gains. Grapheneoxidehas been intensively studied by the scientific community due to its highthermal conductivity, high mechanical strength and flexibility and large surfacearea.Furthermore, it has functional groups, such as carbonyl, that make it hydrophilic,which allows it to be dispersed in various liquid media, such as water. Inthiswork,we intend to evaluate the thermomechanical behavior of class 35 concretewithdifferent concentrations of graphene oxide rich in carbonyl groups (CGO) andsubjected to high temperature gradients (300ºC, 600ºC and 900ºC), inadditiontoambient temperature. Firstly, the concrete was dosed with concentrationsof 0,02%,0,03% and 0,05% of CGO on the weight of cement to determine the percentagethatmost contributed to the improvement in the tested properties. The0,02%concentration showed a considerable reduction in absorption of water andvoidcontent, in addition to an increase of 33% in compressive strength, 18%intensilestrength and 28% in the static modulus of elasticity, when compared to thereferenceconcrete without CGO. This concentration was then exposed to high temperatures,as well as the reference concrete, in order to compare the results obtained. Onceagain, the best results came from concrete with a concentration of 0,02%of CGO,which achieved an increase of 20% in compressive strength and 17%intensilestrength, in addition to a 10% increase in the static modulus of elasticity. It isconcluded that, for conventional concretes, CGO demonstrated considerablegainsinreinforcement and microstructural properties, due to its active functional groups,which in this case is carbonyl. This compound is capable of influencingthecementhydration process and improving the mechanical properties of concrete.