## 1 Introduction
Through the application of a material-compatible reactive nano-silane, a chemical reaction [11] with each material particle can be activated to change the surface characteristics to become hydrophobic (water repellent) and prevent the possible negative impact of secondary minerals on the future performance of a road structure [4; 12]. In addition, future weathering through chemical decomposition is prevented, or at least minimised, due to the repelling of water or moisture within the pavement structure. The presence of water is a pre-requisite for weathering due to the chemical decomposition that occurs [7]. It follows that the durability of the materials within the pavement structure will be increased by minimising chemical decomposition. This can be achieved through the introduction of minimum criteria, limiting the effect of the influence of water submersion on test samples on the compressive and tensile strengths of materials. This aspect can also be key to the successful treatment of materials in regions of the world subjected to frost-freeze conditions. The nano-silane in itself is not effective nor used as a stabilising agent. The nano-scale particles are too small to bridge the gaps between the granular particles of the road-building materials. Hence, it is used as a modification to a material-compatible stabilising agent (e.g., bitumen or equivalent polymer) in an emulsion form to \"permanently\" attach the stabilising agent (with a larger particle size) to the road-building materials to form a highly flexible durable layer or layers within a pavement structure [4]. The modification of an emulsion through the addition of nano-silane in effect introduces a second emulsifying agent with different characteristics into the mix, leading to a reduction in particle size (e.g., modification of bitumen emulsion) [19; 20]. Smaller particle sizes within the modified emulsion have several advantages [6], including the improved stability of the modified emulsion and the ease of distribution of the emulsion within the construction water, with related advantages during construction. Hence, the advantages of the introduction of material-compatible new-age nanotechnologies into the field of pavement engineering include:  
* Cost factors: naturally available materials can be used at a low risk with an enhanced durability, reducing materials costs with savings in the procurement, transportation and construction costs associated with high quality crushed stone;
* Environmental factors: naturally available materials require less energy for production, i.e., the blasting, transportation, crushing and screening is normally not required. New-age (Nano) Modified Emulsions (NME) stabilisation eliminates the use of cement (the manufacturing of which is a considerable contributor to greenhouse gasses in the world, with an additional associated cost of around USD 70 to USD 80 per ton during manufacturing);
* Energy factors: the constructability of NME stabilisation is less complex, requiring considerably less compaction effort, i.e., energy (due to the introduction of a lubricant as part of the NME), compared to traditional high quality crushed stone layers and requires no heating when added as part of the construction water, resulting in considerable savings in energy. Numerous different materials from all over southern Africa have been tested, determining the primary and secondary minerals through X-Ray Diffraction (XRD) scans [4] and successfully evaluated using tests indicative of basic engineering parameters. These include compressive strength, tensile strength and durability (assessing the hydrophobic effect achieved with the modified stabilising agent [12]) to ensure that the risk profile in terms of the category of road is met over the design period [18; 21]. These materials vary from material with CBR > 45 per cent at 95 per cent mod AASHTO [22; 23], to fine Kalahari Sands to highly weathered granites and laterites and include materials containing a high percentage of clays.