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

摘要

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 3-110nm from 6.5-450nm in composites with PAAD, in contrast to 5-210nm 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.