## 2 Applicable Nanotechnology Solutions to Road Maintenance
### Clear-Seal Applications
The corresponding conditions of the G1 [18] test sections (where the Marvil tests were performed) after cleaning the surfacing from any loose material through light brushing with a hand brush are shown in Figure 9.  
Figure 6: (**a**) poor-quality clay material (G10 quality material [18]) compacted to 93% mod AASHTO [19; 20] and hand-sprayed with a GE-NANO clear-seal until saturation; (**b**) After drying of the clear-seal, water was poured onto the treated section—the shape of the water drops shows the level of hydrophobicity achieved on the surface of the red-clay material (refer Figure 3). Figure 8: Condition of the G1 quality [18] base layer at the University of Pretoria, Engineering 4 facility after being open for 9 months from 21 August 2020 to 20 May 2021: **(a)** Untreated G1 layer subjected to rain; **(b,c)** GE-NANO clear-seal treated G1-layer subjected to rain; **(d)** Clear-seal treated G1 layer subjected to rain and light traffic. Figure 7: NPNS clear-seal application on an unprotected G1 quality [18] base layer at the Engineering 4 facility at the University of Pretoria, showing the effect of truck turning movements on sections treated with the clear-seal [18] (left) versus untreated section (right)—the application was performed by hand sprayer to saturation. The effect of the GE-NANO clear-seal as measured in Table 1 and the corresponding photographs in Figure 9 are conclusive. The clear-seal application protected the G1 quality [18] crushed stone base layer over a period of 9 months without any surface damage and reduced the water ingress by a factor of 10. Although the surfacing experienced some damage under the action of light traffic over a period of 9 months (Figure 9c), the base layer still retained considerable resistance to water ingress, which is still one-fifth of that of the untreated G1 [18] base layer section. The G1 [18] base layer subjected to light traffic over a period of 9 months illustrates the depth of protection provided by the clear-seal application. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline
**Permeability Measured on the G1 Quality [18] Base Layer per Volume of Water** & **G1 Quality [18] Base Layer—Untreated (Figure 8a)** & **G1 [18] Layer—Treated with a NINS GE-NANO Clear-Seal Applied at \(\pm\) 1 L/m2—No Traffic (Figure 8b,c)** & **G1 [18] Layer—Treated with a NINS GE-NANO Clear-Seal Applied at \(\pm\) 1 L/m2—No Traffic (Figure 8b,c)** & **NPNS GE-NANO Clear-Seal Applied at \(\pm\) 1 L/m2—No Traffic (Figure 8d)** \\ \hline @ 50 mL & 0.370 L/h & 0.035 L/h & 0.059 L/h \\ \hline @ 100 mL & 0.260 L/h & - & - \\ \hline @ 150 mL & 0.207 L/h & - & - \\ \hline
**Permeability at different intervals** & & & \\ \hline
20 mL & - & 0.030 L/h & - \\ \hline
25 mL & - & - & 0.061 L/h \\ \hline
75 mL & 0.279 L/h & - & \\ \hline
**Average Permeability** & 0.279 L/h & 0.030 L/h & 0.061 L/h \\ \hline \end{tabular}
\end{table} 
Table 1: Penetration rates tested using Marvil apparatus of the application of a NPNS GE-NANO clear-seal on an exposed G1 quality [18] base layer at the Engineering 4 facility at the University of Pretoria (date applied—21 August 2020; date tested—20 May 2021)—test duration on each section = 1 h.  
Figure 9: **(a)** Condition of G1 [18] unprotected surfacing subjected to 9 months of rain in 2020/21 Pretoria, South Africa (loosened material brushed clean); **(b)** G1 [18] base layer with a GE-NANO clear-seal applied after 9 months of rain in 2020/21 and no traffic; **(c)** Cleanly brushed surfacing of G1 [18] base layer treated with a GE-NANO clear-seal subjected to 9 months of rain and light traffic. 1.3 Treatment of Road Section with Some Severe Crocodile Cracking (Alligator Cracking) in the Wheel-Tracks  
Similar to the measurements on the G1 quality [18] base layer, the effect of an application on a GE-NANO clear-seal (diluted NPNS) was shown on a severely compromised surfacing exhibiting severe crocodile cracks (alligator cracks). The condition of the surface with the Marvil apparatus is shown in Figure 10a before any treatment.