# Multifunctional Graphene-Concrete Composites: Performance and Mechanisms
## 2 Experimental Program
### Sample Preparation  
The instruments utilized in this study included an analytical balance manufactured by Shanghai Shangping Instrument Co., Ltd., located in Shanghai, China, an ultrasonic material emulsion disperser (model TH-100), and an adjustable high-speed homogenizer (model FSH-2A), with daily tap water as the dispersing medium.  
According to the specifications for the target test block, the mass ratios of cement, coarse sand, stone, and water was as follows: m (cement):m (coarse sand):m (stone):m (water) = 1:0.58:1.39:0.47 (see Figure 1a). The total volume of the concrete mixture was 0.02 m\({}^{3}\), resulting in a total mass of approximately 52.6 kg. The graphene contents for the target test blocks were set at 4.728 g, 8.944 g, 14.184 g, and 18.912 g. Accordingly, four groups of dispersion liquids with varying graphene concentrations were prepared, corresponding to mass ratios of cement to graphene of 1:0.002, 1:0.004, 1:0.006, and 1:0.008, respectively. To prepare the dispersion solution, each amount of graphene was first weighed using an analytical balance and placed in a 500 mL beaker. Subsequently, 400 mL of water was added, and the mixture was subjected to vibration using a 325 W ultrasonic material emulsifier for 5 min. This was followed by stirring with an adjustable high-speed homogenizer at a speed of 8000 rpm for 3 min. Finally, an additional 1038 mL of water was added, and the mixture was stirred until homogeneous, resulting in a graphene dispersion (see Figure 1b). The graphene dispersion was then mixed with the concrete, stirred at 1000 rpm for 5 min, and poured into a mold that had been coated with a release agent. The mixture was slightly above the upper edge of the mold before being placed on a shaking table for vibration compaction. The concrete test blocks were prepared within 3 h post-dispersion configuration (see Figure 1c). To prevent water evaporation after the test blocks were formed, they were immediately covered with an impermeable film. The curing conditions for the test blocks were maintained at a temperature of 18 \({}^{\circ}\)C and a relative humidity of 90%, with curing durations of 3 days, 7 days, and 28 days.  
As illustrated in Figure 2, a total of 20 test blocks with dimensions of 100 mm \(\times\) 100 mm \(\times\) 100 mm were prepared for this experiment. Each set comprised four test blocks, including one group without graphene and four groups containing suspensions with varying graphene concentrations. The first three test blocks in each group  
\begin{table}
\begin{tabular}{c c} \hline
**Components of Concrete** & **Chemical Composition** \\ \hline cement & calcium oxide, silicon dioxide, aluminum oxide, iron oxide \\ \hline coarse sand & silicon dioxide \\ \hline crushed stone & silicon dioxide, iron oxide \\ \hline graphene & carbon \\ \hline tap water & water \\ \hline \end{tabular}
\end{table}
Table 1: The chemical composition of each component in concrete.  
underwent compressive testing, while the fourth test block in each group was used for photothermal and impermeability testing.  
The experimental procedure is systematically illustrated in Figure 3, which presents a comprehensive flowchart delineating the sequential steps and methodological framework employed in this study.