# Mechanical, Electrical and Fractural Characteristics of Carbon Nanomaterial-Added Cement Composites
## 3 Results
### Porosity  
The porosity test results of the CNM/cement composites after 28 days of curing are discussed in this section. The test results are presented in Figure 9. The highest porosity was observed for CNF/cement composites with a CNF content ratio of 0.6%. The porosity of the CNM/cement composite sample increased up to 10.3% for 0.6% CNF content compared to that of the cement-only sample. Considering the CNF-added cement composite porosity results along with its mechanical and fractural characteristics results, it was determined that a high porosity significantly hampered the mechanical and fractural characteristics. Meanwhile, the mechanical properties and fractural characteristics improved when porosity was the lowest, i.e., at 1.0% CNF-content ratio.  
For GNP/cement composites, maximum porosity occurred at a GNP dosage of 0.6%. The porosities of the GNP/cement composite samples increased by 7.3%, 6.03%, and 7.6%  
Figure 9: Porosity diagram of CNT/cement composite samples, GNP/cement composite samples, graphene/cement composite samples, and CNF/cement composite samples with increasing CNM content ratios at 28 days of curing.  
when GNP dosages were maintained at 0.1%, 0.3%, and 1.0%, respectively. Compared to the porosity results reported in Figures 5 and 6, the compressive strength and fracture toughness decreased at a GNP content of 0.6%. Meanwhile, the flexural strength fracture energy, and fracture toughness of GNP/cement composites showed maximum improvement when the porosity value was lowest, namely, at 1.0% GNP content.  
For graphene/cement composites, the maximum porosity was observed in the 0.3% graphene-added composite. A further increase in the graphene dosage led to a drastic decrease in the porosity of the cement composite. Considering the results of the mechanical and flexural characteristics, it is noteworthy that the compressive strength, flexural strength, fracture energy, and fracture toughness showed the lowest values for cement composites with 0.3% graphene content. In contrast, at 1.0% graphene content, the cement composite showed the lowest porosity but significantly improved compressive, flexural strength, and fractural characteristics.  
For CNT/cement composites, a reduction in porosity was observed as the CNT content was increased to 0.6%. Further increasing the CNT dosage to 1.0% significantly increased the porosity. A drastic increase in porosity also led to a decrease in the mechanical and fractural characteristics of 1.0% CNT-added cement composites. In contrast, when porosity was low, namely, at a 0.6% CNT dosage, the flexural strength and fractural characteristics showed the maximum improvements. Hence, it may be that a decrease in porosity is closely related to the mechanical and fractural characteristics.  
Apart from reduced porosity, the improvement in the mechanical and fracture characteristics of cement composites containing CNMs can also be attributed to other beneficial characteristics of CNMs, such as their ability to bridge cracks and serve as nucleation sites for cement hydration products. Additionally, factors such as the dispersion quality and aspect ratio of different types of CNMs also influence the mechanical and fracture characteristics of CNM-enhanced cement composites.