Study on the Effect of Graphene Oxide with Low Oxygen Content on Portland Cement Based Composites

Abstract

The current study presents research into the effect of graphene oxide (GO) with a carbon to oxygen ratio of 4:1 on the fluidity, hydration, microstructure, mechanical and physical properties of Portland cement pastes and mortars. The amounts of GO investigated were 0.02%, 0.04%, and 0.06% by weight of cement, while for mortars, an extra composition with 0.1% was also prepared. According to the results, the fluidity of cement paste and mortar increased and the hydration process was slightly retarded with the addition of GO. Despite this, improvements in compressive and flexural strength were established in the mortars containing GO. The maximum effects (~22% and ~6%, respectively) were obtained with the addition of 0.06% GO. The calculation of estimated strength proportional to samples of equal density showed that for mortars cured for 7 days the gain in strength was directly related to the gain in density. For mortar samples cured for 28 days, the estimated strength was found to be significantly higher than that of the reference sample, indicating that besides density there are other factors determining the improvement in strength of mortars modified with GO. The possible structure strengthening mechanisms are discussed.

Efficient Use of Graphene Oxide and Silica Fume in Cement-Based Composites

“…The peak intensity of the portlandite lowered as time passed. These results are consistent with previous findings in the literature [ 23 , 28 , 49 ].…”

Efeitos do reforço na pasta de cimento portland com óxido de grafeno obtido por métodos de química verde

“…Quando foi adicionado 0,10% de GOv à pasta de cimento, observou-se um aumento de 14,7% na resistência mecânica. Esse valor é similar ao descrito por KUDŽMA e colaboradores, que observaram o aumento de cerca de 15% ao adicionar a mesma quantidade de GO [35]. A série de ensaios mostrou um pico de resistência à compressão, quando foi adicionado 0,30% de GOv à pasta de cimento, com incremento de 65,6% na resistência à compressão em relação ao material de referência.…”

“…BABAK e colaboradores [5], em pesquisas realizadas com GO e cimento, observaram que os produtos de silicatos de cálcio hidratado do cimento se depositaram na superfície GO, que atuou como um local de nucleação e os silicatos apresentaram uma grande adesão em sua superfície. KUDŽMA e colaboradores [35] observaram que a melhora nas propriedades mecânicas pode estar associada, principalmente, à compactação da estrutura, redução na descontinuidade e na porosidade da microestrutura da matriz cimentícia. Já WANG e colaboradores [20] observaram que dosagens de GO resultam em cristais de portlandita mais refinados.…”

“…O ganho na resistência mecânica apresentado pelo grafeno e o GOv, onde (I) WANG, et al [20], (II) KUDŽMA, et al [35] e (III) BABAK, et al [5] A análise de microscopia (MEV) do corpo de prova com 0,30% e de 1,00% de GOv é apresentado na Figura 9. Nessa figura podem ser observadas as folhas de GO, que atuam no sítio de hidratação, favorecendo o crescimento de cristais de fases portlandita e silicato de cálcio hidratado, como descrito na literatura [5,20,34].…”

Effect of Graphene Oxide on the Crystallization of Calcium Carbonate by C3S Carbonation

“…Due to the excellent mechanical properties of GO, the possibility of its application in cement has been extensively explored. Previous studies have reported that addition of GO promoted the hydration of cement and significantly increased the compressive and flexural strength of cement [37,38,39]. In a recent study, Lv et al [40] found that the addition of GO was capable of affecting the shape of cement hydration products, such as ettringite (AFt) and monosulfate (AFm).…”