4th International Conference on Transportation Infrastructure (ICTI) Laboratory Evaluation of Road Construction Materials Enhanced with Nano-Modified Emulsions (NMEs) 4th International Conference on Transportation Infrastructure (ICTI) I Akhalwaya and FC Rust 9 July 2018

Overview Brief Introduction to Nanotechnology Standard Bitumen Emulsions vs NMEs CSIR Laboratory Results and Discussions Concluding Remarks The way forward for NMEs

Introduction What is Nanotechnology? Lots of misconceptions about nanotechnology

Definition of Nanotechnology Simplest Definition: “Nanotechnology is the next biggest thing that's really small” – Unknown Scientific Definition: “Nanotechnology may be defined as the term used to cover the design, construction and utilisation of functional structures with at least one characteristic dimension measured in nanometres (nm)” - Kelsall et.al (2005)

Relative scale of a Nanometre (nm) What potential impact does this have? - (Justin Kavanagh, 2017)   Tennis Ball = 1 Nanometre Earth = 1 Metre

Chemistry of Standard Bitumen Emulsions Bitumen Particle   Bitumen Particle + Emulsifying Agents   Sea of Water Molecules (Blue Shading)

Standard Emulsifier of a Bitumen Emulsion Non-Polar Tail (hydrophobic and lipophilic) Polar Head (hydrophilic and lipophobic)   Single Janus Particle of a traditional bitumen emulsifier

What is a Nano-Modified Emulsion (NME)? NME = Standard Bitumen Emulsion + Nano-additives Types of nano-additives found in NMEs: Combination of Nano-Polymers and/or Organo-Silanes Provides extremely low-viscosities. Provides a NME material with hydrophobic properties It improves the distribution and coverage which allows for smaller quantities of residual bitumen to be used

How do NMEs Work?

Visual Representation of a Siloxane surface Water droplets were coloured in blue for visual presentation

Visual Hydrophobic Test Standard Bitumen Sample after 3 hours NME Sample after 3 hours

Laboratory Investigation: Materials Tested X-Ray Diffraction (XRD) Results of Raw materials 17-20% Mica (Muscovite) and a 7-43% clay minerals (Smectite/Kaolinite) i,e. marginal quality materials “Independent material tests showed the material was not suitable for cement stabilisation as they were unable to achieve the minimum strength requirements with the specified cement quantity” Source: Jordaan et al. (2017a)

The Common Norm in this Scenario VS NMEs Imported high quality granular base and subbase layers High-Costs Exorbitant Transportation costs of hauling large quantities of materials, especially from further distances.. or alternatively: Stabilisation using a standard bitumen emulsion High percentages of stabilising agent will be needed to meet design criteria – High Costs Or ideally the best scenario: Stabilisation using a NME

Benefits of NMEs applicable To This Scenario • Improved performances • Required design strength is obtained using low percentages of residual bitumen as well as nano-additives • Enables the use of locally available marginal materials and at lower risk • Improved resistance to water damage due to the rejection of the water from the bitumen-aggregate bonding process Source: Jordaan et al. (2017b)

Sample Description for Strength Tests Sample Description, Information and Properties Stabilising Agent SS60 anionic nano-modified emulsion (NME) with organo-silane and nano-polymer additives Standard SS60 anionic emulsion without any additives % of stabilising agent added 0.7% per mass % of cement content None Optimum Moisture Content (OMC) % 6.0 Sample Diameter (mm) 150mm Ф Sample

Laboratory Results SS60 anionic nano-modified emulsion (NME) with organo-silane and nano-polymer additives Standard SS60 anionic emulsion without any additives Test Performed UCS** (Dry) UCS (Wet) ITS*** (Dry) ITS (Wet) UCS (Dry) ITS (Dry) Average (kPa) 2430 1923 179 158 2218 558 145 36 NME Equivalent Classification (Jordaan et al. 2017b) NME2 Not suitable for NME treatment due to materials not meeting any specification BSM* Equivalent Classification (TG2, 2009) BSM2 Not suitable for BSM treatment due to materials not meeting any specification *Bituminous Stabilised Material (BSM) **Unconfined Compressive Strength (UCS) *** Indirect Tensile Strength (ITS)

Summary and Discussion of Results UCS Dry - 10% increase in strength UCS Wet - 244% increase in strength ITS Dry - 23% increase in strength ITS Wet - 338% increase in strength Performs extremely well under wet conditions relative to standard bitumen emulsions Limitation in terms of results displayed for Standard Bitumen Emulsion

Concluding Remarks Lot of misconceptions about the use of nanotechnology, including NMEs – attend the NME seminars and workshops Preliminary tests indicate that NME materials perform significantly superior to traditional bituminous stabilised materials The required design strengths obtained exceeded expectation using low percentages of stabilisation agent The overall laboratory evaluation concludes that NMEs may in fact be used to enable the cost-effective use of locally available marginal materials at lower risk, which may have direct implications for improved cost-effective pavement design alternatives in the future So does mean that NMEs are better?

The Way Forward for NMEs Performance Testing Full-scale Laboratory Programme needed with more specialised laboratory studies needed Heavy Vehicle Simulator (HVS) tests on NME trial projects to verify laboratory results Economic Studies Economic models and Life-Cycle Cost Analysis Environmental Studies Risk Evaluation studies and Environmental Impact Assessments (EIAs)

Where do NMEs currently stand in SA? HVS testing and continuous Laboratory investigation at the CSIR International and Local Collaboration Source: as cited in Steyn (2011)

Acknowledgements Prof. Gerrit Jordaan Dr. Louw du Plessis Mr. Martin Murphy Mr. Thomas Modise CSIR Transport Infrastructure Engineering Staff and Laboratory Technicians

Thank you! Questions? Elsevier