## 2 Applicable Nanotechnology Solutions to Road Maintenance
### Clear-Seal Applications  
As discussed, various material surfacings were treated and tested to measure and quantify the impact of the clear-seal application. In all examples, the clear-seal was applied by hand sprayer to saturation of the material as shown in Figure 5, at a rate adjusted by eye to limit (prevent) run-off of the clear-seal and to optimise application rates. 1.1 Treatment of a Poor-Quality Material Containing More than 25 Per Cent Kaolinite Clay at the University of Pretoria, Engineering 4 Facility  
A small section of this compacted material was treated to test the hydrophobic nature that can be achieved with the GE-NANO clear-seal treatment. The material consisted of a poor quality G10 [18] clay-based material compacted to 93% mod AASHTO [19; 20] as shown in Figure 6a. The treated section is shown as an inset in Figure 6a. After drying, water was poured onto the treated surface, the effect of which is shown in Figure 6b. Figure 5: **(a) Application of a clear-seal by hand sprayer at a rate of approximately 1 to 2 L/m\({}^{2}\) (about 5 to 10 mL of NPNS/m\({}^{2}\) at a material cost of about US$ 0.10/m\({}^{2}\) to US$ 0.20/m\({}^{2}\))—note the close proximity of the sprayer head to the road surface to prevent loss during windy conditions; (b) The dried surfacing 30 min after application of the clear-seal with a Marvil apparatus placed on top of the surfacing to measure the rate of water penetration into the treated surface. **  
The leading of the water shows the high degree of hydrophobicity achieved through the treatment of the poor material (compare Figure 3). No water penetration tests were performed on this poor-quality material. 1.2 Treatment of a Good G1 Quality Crushed Stone Base Layer That Has Not Been Primed at the University of Pretoria, Engineering 4 Facility  
A section of a newly constructed good G1 quality [18] base layer compacted to 88% of ARD [21] was left untreated without any surfacing or protective prime at the newly constructed Engineering 4 facility at the University of Pretoria. As a \"worst case\" scenario, the impact of the application of the GE-NANO clear-seal on this untreated granular layer was measured and quantified. The same clear-seal product (as applied on the red-clay material shown in Figure 6), was applied by hand-spay to the exposed base layer at a rate to saturation. The materials cost of the application of the GE-NANO clear-seal was approximately US$ 0.08/m2 to US$ 0.12/m2. Shortly after application of the protective clear-seal, 5 mm of rain fell at the site and the protective impact achieved through the application of the clear-seal product was tested through the turning of a truck over the treated and untreated G1-quality [18] base layer, the visual effect of which is shown in Figure 7.  
Nine months after application of the GE-NANO clear-seal, the Marvil apparatus was used on the G1-quality [18] layer to test the rate of penetration of the water into the G1 [18] layer. Tests were performed on an untreated section of the G1 [18] base, on a section of the G1 [18] base that was treated with the clear-seal, but not subjected to any traffic and on a section treated with the clear-seal and subjected to light vehicle traffic over the nine-month period. The conditions of the G1 quality [18] crushed-stone base layer test sections after a period of 9 months are shown in Figure 8. The penetration rates of the G1 layer after being exposed to elements for more than 9 months with some vehicle movement on some sections are summarised in Table 1. The period covered spanned the 2020/21 summer rain-fall season--an unusually good season in terms of the rain recorded. The water damage from the rain on the exposed G1 [18] base layer with no application of the clear-seal can be seen in Figure 8a.