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.
