INDUSTRY INSIGHT
Value engineering for
flexible pavements
The well-established science of nano technology provides an economical and highly viable proven alternative for maintaining and building road pavement structures. Martin Murphy, Managing Director, GeoNano Technologies, presents his business case and the company’s engineered solutions.
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perating nationally and internationally, GeoNano Technologies is widely regarded as a pioneer in the development and adoption of proven solutions for road pavement designs and construction. Material evaluation and bitumen emulsion tests are conducted in-house at the company’s materials and product research laboratory in Germiston, Gauteng. “We are proud to be involved with the highest ranked Faculty of Engineering in Africa, having sponsored several final-year and post-graduate students, enabling us to build the foundation for a sound engineering background to our products,” Murphy explains. “Through the involvement of these students and academics, we have identified the best available new-age (nano-size) technologies. We’ve improved products and developed optimal design methods based on fundamental scientific principles, making them universally applicable. Our products can be used with confidence to add value and contribute to the cost-effective, much needed service delivery of transportation infrastructure,” he continues. A considerable reduction in road unit costs can be achieved by using material-compatible
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IMIESA October 2020
and safe modifying agents that chemically modify traditional stabilising agents, such as bitumen emulsions (or equivalent). This modification enables the stabilising agent to chemically attach to the particles of naturally available stone/gravel/soil materials. The chemical attachment (absent in the normal use of bitumen products, which relies on electrical and mechanical forces through interlocking and absorption to gain strength) considerably improves bond strengths. These high chemical-bond strengths enable the use of naturally available materials in all pavement layers of roads, meeting (usually exceeding by some margin) the engineering requirements in terms of stresses, strains and durability in any pavement layer.
Understanding mineralogy The key to the successful use of modifying agents is in the science associated with the mineralogy of the materials and the identification of a compatible modifying agent with high inter-element bonds – i.e. a sound scientific chemical basis of design. The small particle sizes (nano-size) of the modifying agents enable a large coverage area, (1 litre of nano-sized material could exceed the
coverage area of 1 000 litres of bitumen). This allows for deep penetration into the material. The small particles also attach to secondary minerals found in naturally available material and render them hydrophobic (water repellent). Hence, any possible negative influence of these secondary minerals on the future behaviour of a road can effectively be neutralised using a scientifically designed, material-compatible modifying agent in the emulsion.
NME agents The proven concept of these New-Age modifying agents of emulsions (NME) has been demonstrated with the scientific testing and use of NME stabilisation of in-situ materials (ranging from fine Kalahari sands to the use of G8/G7 materials in base/sub-base layers, etc.) in the design and construction of several roads. Accelerated pavement testing (APT) has also Martin Murphy, Managing Director, GeoNano Technologies
