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.

Original graphene oxide (GO) nanosheets were prepared using the Hummers method and found to easily aggregate in aqueous and cement composites. Using carboxymethyl chitosan (CCS) as a dispersant, few-layered GO nanosheets (1–2 layers) were obtained by forming CCS/GO intercalation composites. The testing results indicated that the few-layered GO nanosheets could uniformly spread, both in aqueous and cement composites. The cement composites were prepared with GO dosages of 0.03%, 0.05% and 0.07% and we found that they had a compact microstructure in the whole volume. A special feature was determined, namely that the microstructures consisted of regular-shaped crystals created by self-crosslinking. The X-ray diffraction (XRD) results indicated that there was a higher number of cement hydration crystals in GO/cement composites. Meanwhile, we also found that partially-amorphous Calcium-Silicate-Hydrate (C-S-H) gel turned into monoclinic crystals. At 28 days, the GO/cement composites reached the maximum compressive and flexural strengths at a 0.05% dosage. These strengths were 176.64 and 31.67 MPa and, compared with control samples, their increased ratios were 64.87% and 149.73%, respectively. Durability parameters, such as penetration, freeze-thaw, carbonation, drying-shrinkage value and pore structure, showed marked improvement. The results indicated that it is possible to obtain cement composites with a compact microstructure and with high performances by introducing CCS/GO intercalation composites.

This study focused on the uniform distribution of graphene oxide (GO) nanosheets in cement composites and their effect on microstructure and performance. For this, three polymer dispersants with different level of polar groups (weak, mild, and strong) poly(acrylamide-methacrylic acid) (PAM), poly(acrylonitrile-hydroxyethyl acrylate) (PAH), and poly(allylamine-acrylamide) (PAA) were used to form intercalation composites with GO nanosheets. The results indicated that GO nanosheets can exist as individual 1–2, 2–5, and 3–8 layers in GO/PAA, GO/PAH, and GO/PAM intercalation composites, respectively. The few-layered (1–2 layers) GO can be uniformly distributed in cement composites and promote the formation of regular-shaped crystals and a compact microstructure. The compressive strengths of the blank, control, GO/PAM, GO/PAH, and GO/PAA cement composites were 55.72, 78.31, 89.75, 116.82, and 128.32 MPa, respectively. Their increase ratios relative to the blank sample were 40.54%, 61.07%, 109.66%, and 130.29%, respectively. Their corresponding flexural strengths were 7.53, 10.85, 12.35, 15.97, and 17.68 MPa, respectively, which correspond to improvements of 44.09%, 64.01%, 112.09%, and 134.79%.

The collagen obtained from chrome leather waste can be used to modify graphene oxide (GO) to prepare polyvinylidene fluoride (PVDF) composite ultrafiltration membranes, a process that is conducive to the recovery of leather waste, comprehensive utilization of GO and improved performance of the membrane. In this paper, collagen-modified GO (CGO) was prepared by degradation of collagen from chrome leather waste and used to prepare a PVDF composite ultrafiltration membrane. The results show that the carboxyl content of CGO and dispersion were improved. The water flux and flux recovery rate of the modified ultrafiltration membrane were improved. The bovine serum albumin (BSA) intercepted on the membrane surface was easy to clean and the antifouling performance improved. The performance of the membrane decreased when the GO content exceeded 0.75 wt%, while CGO can reach 1.0 wt% without agglomeration due to its good dispersion.