Michael Kidgell, Prof Wynand JvdM Steyn, Prof Gerrit Jordaan Effect of Nano-Modified Emulsions (NME) (Nano-Silanes) Stabilizers on the Properties of Dolomite Michael Kidgell, Prof Wynand JvdM Steyn, Prof Gerrit Jordaan 8 July 2019

The Problem Provision of good transport infrastructure, preservation & timely rehabilitation prerequisites to economic growth Costs continuously increasing - consuming scarce available funds Investigation, testing and application of “alternative” new road building products, including nano-materials essential Effect of nano-silanes stabilising agent on properties of dolomite material evaluated

Methodology Main objectives determine whether stabilising agent would make dolomite water-repellent reduce moisture sensitivity of dolomite improve understanding of material behaviour 22 samples Neat & Stabilized Grading tests & Atterberg Limits Optimum Moisture Content X-Ray Diffraction (XRD) & X-Ray Fluorescent (XRF) 0.075 mm & 0.425 mm fractions

Main results XRD scans Ankerite contained mainly Quartz (SiO2)(>20%) Illite (2 to 3%) Kaolinite (<2%)

Main results Importance of identifying presence & type of clays Neat material average GM of 2.36 - relatively good quality G4 material AASHTO A-1-a (gravel sand) Stabilised material NME1 - recommended material classification system for Nano-Modified Emulsions (Jordaan et al., 2017a) and TG2 (Asphalt Academy, 2009)

Atterberg Limits - Neat & Stabilised Material Effect of nano-silanes Deep penetration into substrates achieved due to small molecular size (<5 nm in size) Interaction of nano-silanes with free energy surrounding molecules of natural materials, changes surface atom arrangements of aggregates Nano-silanes react with themselves and any hydroxy (OH) groups within substrate when moisture is present, forming silicone resin network Smaller nano-silane particles formed protective layer - reducing susceptibility of dolomite to water Dolomite effectively water-repellent - preventing water reacting with problem minerals in dolomite & causing weathering

Benefits 40 000 l water saving per 1 km of 2-lane road Water-sensitivity of Dolomite Nano-silane treatment

Conclusions Addition of nano-silanes stabiliser improved properties of dolomite slight reduction in plasticity of soils - reducing effect of moisture variations acted as lubricant for compaction proposed classification system & materials criteria allows for better utilisation of naturally available materials possible & practical Cost-effective, safe & sustainable road infrastructure