Preservation of gravel roads to make them durable and erosion resistant using technology disruptor NANO-silanes

Abstract

The length of gravel roads in South Africa outnumbers the length of paved roads by a factor of three to four. Gravel roads have known lower vehicle/kms, but their mobility and access provision for communities are well recognised via initiatives like Sustainable

Mobility for All (SUM4All) and overall Sustainable Development Goals (SDGs). The ever- decreasing gravel source issue coupled with diminishing maintenance and upgrade

actions, place the maintenance and retention of gravel road networks under significant threat. The new draft TRH 24 (SANRAL, 2022) promotes the use of latest new-age modified emulsions (NME) using nano-technology (Nano-Silanes) as a low cost technology to upgrade to bituminous surfaced weather proof standards. This NME technology has real technology disruptor potential regarding the improved utilisation of lower quality natural granular materials in roads in general enabling lower cost in gravel road upgrade to paved bituminous surfaced standards. The case for application of this nano-technology for lower cost improved maintenance of gravel roads is made. NME is promoted here to be used as (special) gravel road maintenance, therefore not upgrade to paved standard. It has the potential for gravel preservation and makes sense with lesser funding and legislative hurdles as a gravel maintenance action in stead of upgrading such low traffic volume gravel roads to bituminous surfaced standard. If a gravel road status is retained the geometric and drainage design specifications do not have to be upgraded as for when it was to be upgraded to paved bituminous surfaced road standards. Thus, significant additional costs can be saved by retaining the road as a gravel road. Durable enhanced engineered low traffic volume gravel roads and streets can be provided by means of nano-technology. It retains the gravel road colour. This helps to manage public perception and expectations in terms of a darker colour that implies bituminous upgrading and higher standards. It makes the gravel surfacing and base water and erosion resistant with improved maintenance and operational functionality. Case studies are briefly referenced to demonstrate the potential.