## 4 Conclusions  
\(\upmu\)CT reveals the internal geometry of the fabric reinforced composite materials, showing the overall image of the composite from the impact point towards the edge of the sample and the fiber breakage, notch, or depth of the impact areas. The advantages of this technique are that it not only shows the impact area but also very clearly shows the fiber rupture in the different slice images. Furthermore, other parameters--like porosity and sample position--can be obtained from the 3D image. The mechanism of damage of the composite is well explained on the basis of the \(\upmu\)CT investigation of the damaged area. The following conclusions can be deduced from the obtained results:  
1. Fabric reinforced composites were much less affected by the mechanical impact than the E-glass and the basalt reinforced composites.  
2. As examined for basalt composites, \(\upmu\)CT was found to be one of the most useful techniques for examining the different failure mechanisms for geopolymer composites.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Experimental Parameters** & **Carbon Composite** & **E-glass Composite** & **Basalt Composite** \\ \hline Number of Layers & 65 & 99 & 86 \\ Number of fibers & 174 & 520 & 423 \\ Number of closed pores & 0 & 0 & 5 \\ Volume of closed pores (mm\({}^{3}\)) & 0.0 & 0.0 & 0.04 \\ Surface of closed pores (mm\({}^{2}\)) & 0 & 0 & 1.96 \\ Closed porosity percentage (\%) & 0.0 & 0.0 & 0.06 \\ Volume of open pore space (mm\({}^{3}\)) & 99.61 & 242.37 & 559.99 \\ Total porosity \% & 17.78 & 43.27 & 89.80 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Parameters for the analysis of 3D images of impacted composites in the \(\upmu\)CT techniques (pixel size: 16 \(\upmu\)m).  
3. \(\upmu\)CT provided the internal geometry (including 3D image) of the fabric reinforced composite materials, including parameters like porosity and sample position. This is the prime advantage of \(\upmu\)CT over other techniques.  
4. Our study showed that the durability of the carbon fiber reinforced composite showed better residual strength in comparison with the E-glass fiber one.  
5. The carbon fiber reinforced composite had a much better impact resistance, with fiber damage only in the central area with a limited amount of fiber sliding in the surrounding areas.  
The following are available online at [[http://www.mdpi.com/2076-3417/9/3/516/s1](http://www.mdpi.com/2076-3417/9/3/516/s1)]([http://www.mdpi.com/2076-3417/9/3/516/s1](http://www.mdpi.com/2076-3417/9/3/516/s1)), Figure S1: SEM images of E-glass geocomposite after damage, showing matrix rupture, fibre pull out and non-adhesion. Figure S2. SEM images of Basalt reinforced geocomposite after impact test, showing the fiber breakage, matrix cracks, non-adhesion of fabric-matrix interface, Video S1: 3D analysis of basalt fiber from center to edge in basalt fiber reinforced composite  
[PERSON], [PERSON], [PERSON] and [PERSON] conceived and designed the experiments; [PERSON], [PERSON] and [PERSON] performed the experiments; [PERSON], [PERSON] and [PERSON] analyzed the data; [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] wrote the paper.  
[PERSON] is grateful to the MIUR for the grant \"Fund for basic research activities\", and to the Department of Civil Engineering and Architecture of the University of Catania for supporting the project MATErials LIfe foreCAst (MATELICA).  
The authors declare no conflict of interest.