BITUMEN & ASPHALT
NME innovations for Africa To ensure available funds are spent wisely, design engineers need to consider the most appropriate construction techniques, says Martin Murphy, managing director, GeoNano Technologies. These include the proven benefits of new-age modified emulsions (NMEs).
T
he new-age modification of surfacing materials can substantially improve a road’s structural characteristics. For example, binders can be modified to, inter alia, have a higher resistance to ‘ageing’ (oxidation of volatiles, which results in brittleness of binders and cracking) under the harsh environmental conditions experienced on the continent. Furthermore, new-age modifiers increase the maintenance-free life of the surfacing and provide user-friendly materials ideally suited for maintenance activities, resurfacing and the surfacing of new roads. Since they are placed at ambient temperatures, considerable savings in energy input are realised. The placement of surfacings at ambient temperatures also makes NME ideally suited for labour-intensive construction and maintenance actions. Workers can safely work with the materials, which are modified to adhere to stone/gravel/sand. The modified binder is much less likely to contaminate equipment or adhere to exposed skin.
ABOVE Preparation of GeNANO anionic NME slurry next to the road RIGHT Placement and spreading of the GeNANO anionic NME slurry on existing surfacing
Through the introduction of nano particles less than one thousandth of the size of a bitumen particle, NMEs ensure a high depth of penetration is achieved on existing seals. They further provide a permanent waterrepellent benefit to the application. Such applications will add considerable maintenance-free durability to existing surfacings at a fraction of the cost. Preparing an NME slurry-mix can be carried out next to the road (using simple equipment like a concrete mixer). The placement is equally straightforward using squeeze brooms to ensure that all surface cracks (including micro cracks) are thoroughly sealed.
GeNANO Clear-seal protection of the crush-stone base layer showing the impact achieved under the action of heavy vehicles after some rain
Clear-seals
Martin Murphy, managing director, GeoNano Technologies
The use of GeNANO nano-silane nanopolymer sealant provides a Clear-seal option with additional benefits. Due to the size of the particles used, a water-resistant, highpenetration protective layer is achieved. The application is dry within an hour with no ‘pick-up’ or contamination of vehicles and no repainting of road-markings required. It is easily applied by hand with little training at about 2 ℓ/m². The sealant is also ideally suited for the prime of an exposed base, protecting the base layer against water damage
and vehicle trafficking. A double application of the GeNANO Clear-seal can be used on gravel/ soil roads to protect the gravel layer. It provides a surface with a ‘natural’ look while protecting it from water damage, achieving a high depth of penetration on an existing compacted layer. “GeNANO NME is not a ‘one-size-fits-all’ solution. Adjustments to formulas are made based on the material, minerology analyses and the structural engineering requirements that must be met. Once those parameters have been determined, however, the correct NME application provides a cost-effective and workable solution,” Murphy concludes.
IMIESA January 2021
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