Structure, performances, and formation mechanism of cement composites with large‐scale regular microstructure by distributing uniformly few‐layered graphene oxide in cement matrix

Abstract

The multiple layered graphene oxide (GO) was prepared by modified Hummer's method. Then few-layered GO was obtained by forming intercalation composites with the multiple layered GO and poly(acrylic acid-acrylamide-diallyl dimethyl ammonium chloride) (PAAD). The goal is to prepare large-scale ordered structure in the whole cement composites by distributing uniformly the GO in cement matrix. The effects of PAAD on GO nanosheets and its distribution within the cement paste were investigated and assessed by characterization of the size range of GO nanosheets and microstrcuture of cement matrix. The results showed that the GO nanosheet size can reduce to 3-110 nm from 6.5-450 nm in composites with PAAD, in contrast to 5-210 nm for polycarboxylate superplasticizers. Doping GO/PAAD intercalation composites, the large-scale ordered structural cement composites were prepared. The SEM images indicated that the whole cement composites consisted of regular cement hydration products by interweaving and crosslinking. The X-ray diffraction patterns indicated that there are new crystals in the cement composites and the amorphous hydration products have been transferred into crystal phase. The forming mechanism was proposed according to these research results. The test results indicated that the cement composites have high compressive and flexural strengths, good heat resistance, few cracks, small average pore diameter and good durability.

The Role of Graphene Oxide on the Hydration Process and Chemical Shrinkage of Cement Composites

“…In addition, the calcium hydroxide in the CCG paste exhibits a relatively dense petal shape. The mechanism through which the petal-like crystals are formed indicates that regular crystals are formed by the template effects of the GO and the ordered structures are formed by the interweaving and crosslinking caused by the crystal growth [32]. It can be inferred that the pore structure of the CCG hydration product is denser than that of the blank paste.…”

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

“…Esse melhor ordenamento ocorre através dos planos de GO em interação com os íons de cálcio, que atuam como ponto inicial de crescimento dessas fases cristalinas. Em virtude disso, observou-se o melhor desempenho mecânico pela matriz [36]. Já nas adições superiores a 0,30%, acredita-se que o as unidades de GO façam interação entre si formando agregados de GO, devido ao excesso da nanopartícula em suspensão.…”

Electrochemically Exfoliated Graphene for High-Durability Cement Composites

“…The authors attributed this phenomenon to the results of the porosity measurements, i.e., to the significant refinement of large capillary pores. 16 As a consequence, the decreased mobility of chloride and sulfate ions within cement matrix 16,23 as well as the improved performance of cement composites during freeze-thaw cycles 19,20 and carbonation tests 19,20,22 have been reported in several studies. Similarly, comparable results have been obtained for GNP-cement composites revealing a significantly reduced water penetration depth, even by 75%, 5,21 accompanied by an increased chloride migration resistance.…”

“…Most importantly, it has been reported that the addition of GO notably reduces the sorptivity of cement composites. [15][16][17][18][19][20] The maximum reduction of 46% 18 and 44% 15 has been quantified for initial and secondary sorptivity, respectively, if compared to plain composites. The authors attributed this phenomenon to the results of the porosity measurements, i.e., to the significant refinement of large capillary pores.…”