# Experimental Investigation of Mechanical Properties of Clay-Cement Slurry Containing Graphene Oxide
## 3 Results
### The Microstructural Characteristics of the Grout-Solid Interface  
The cemented broken gravel sample undergoes a microscopic damage process, which involves deterioration and cracking of the structure. As a result, a distinctive microcrack surface morphology is formed. There exists a significant correlation between the microcrack surface morphology and the mechanical properties of the sample [39]. The degree of damage to the sample can be inferred from the microcrack surface morphology, which also reflects the resistance strength of the cemented broken gravel sample to uniaxial load. Therefore, scanning electron microscopy was used to observe the fracture surface of the samples, allowing for further analysis of the reinforcing effect of industrial-grade graphene oxide on broken gravel. This study summarizes and compares the micro-reinforcement modes of different grouting materials for the GO-0 and GO-5 samples with GO dosages of 0% and 0.05%, respectively (refer to Figure 7). Figure 7a shows the presence of clay-cement agglomerates at the GO-0 cement-gravel interface, surrounded by a large number of clay particles forming a skeleton structure with the agglomerates as the core. However, these agglomerates have small volumes with noticeable cracks and low bonding degrees, significantly affecting the macroscopic strength of the reinforcement material. This is the fundamental reason why traditional clay-cement grouts and their reinforced bodies exhibit low initial anti-permeability and filtration abilities in underground water-rich and erosion environments, exhibit low stone strength, and are prone to brittle failure. In contrast, Figure 7b illustrates a significant amount of well-developed clay-cement agglomerates at the GO-5 cement-gravel interface, improving the density of the interface structure compared with GO-0. Additionally, there is no CH crystal present at the cement-gravel interface. A substantial amount of C-S-H gel has already reacted, and the mineral composition is reasonable. The microstructure of the structural body is dense, and the surface bonding density is high. These factors are highly conducive to significantly enhancing the bonding strength of the transition zone between the cement paste and gravel. Compared with the GO-0-reinforced body, GO-5 offers advantages such as a reasonable mineral composition, dense structure, and high interface bonding strength. These characteristics ensure excellent mechanical properties and long-term stability in water-rich environments. These findings align with the results of [PERSON] et al. [40], which suggest that oxidized graphene nanosheets have the capability to enhance the hydration reaction in injection materials. This enhancement is achieved through facilitating the nucleation of oxygen-containing functional groups and altering the morphology of hydration products. This enhancement of the slurry's microstructure contributes to its consistency. In this experiment, the improvement of binding gravel through oxidized graphene primarily lies in the integrity and regularity of the fracture surface. Previous studies have highlighted two main mechanisms by which carbon nanotubes, graphene, oxidized graphene [41], and other nanomaterials enhance the microstructure of cement-based composites to improve their performance. Firstly, the nanomaterials themselves have a nucleation effect, promoting the hydration reaction of cement to generate more C-S-H and transmit additional cement hydration products in microcapillary pores. Secondly, the nanomaterials act as bridges in the microwinkles of materials [42]. In recent years, there has been an increasing application of fractal theory in quantitatively characterizing rock fracture surfaces [43]. [PERSON] and [PERSON] [44] proposed that the failure of specimens under constant external loads is essentially a nonlinear and statistically significant superposition of various microscopic deformation variables.