EFFECT OF STORAGE AND HANDLING ON HIGH BINDER EMULSIONS G. Holleran, Vice President, Valley Slurry Seal Company, USA Prepared For AEMA 2001 meeting San Diego Back to VSS Technology Papers Library Outline Emulsion Basics Test Methods and Emulsion types Results Conclusions Emulsion Basics Emulsions are dispersions of immiscible phases stabilized chemically Emulsions are NOT thermodynamically stable Emulsions settle due to density differences Emulsions flocculate and coalesce due to disruption and transport mechanisms This is time and temperature and handling dependant Emulsion Formation Sheared to a fine particle size Asphalt Dispersed in Water What Do Emulsifiers Do? Create a surface charge at the interface of the asphalt and the water. Create Repulsion and storage stability. Provide wetting. Enhance adhesion (cationic). Gel the asphalt (high float). Control break and cure rate. Emulsifier Emulsified Asphalt    Double Layers   Double Layer Important Factors Charge size Molecular size Charge density HLB Double layer thickness Where is the emulsifier ?- equilibrium time Miscelle formation Instability Mechanisms Water Inclusion Sedimentation Flocculation Coalescence Inversion Ostwald Ripening Test Methods and Emulsion Types Basic emulsion testing equivalent to ASTM D244. Brookfield Viscometer used. Torsional recovery using Mobil method- (same as caltrans). Recovery using evaporation and CT331 Microscopic technique visible developed at Mobil labs and done at Massey university N.Z Storage testing done using forced air ovens on 4 lt cans Stirring done every 24 hrs where appropriate Polymer micrographs done using UV fluorescence Lab Coarsening done using Brookfield viscometer and 100 rpm All formulations meet CRS-1 and CRS-2 basic Caltrans specs Sampling: Sampling: Representative Not under pressure- e.g spray bar Discard first gallon (Minimum) ( T140) Gallon at least- Not smaller Transfer samples to avoid material broken on sides of sampling container Plastic or metal acceptable Sample must be preserved: new containers Protected from freezing Chip Seal Process and Emulsion Properties - Stability The emulsion must remain dispersed until sprayed and aggregate is applied. Test Indication: Storage stability. Shear susceptibility. Important physical properties: Particle size, particle size distribution, particle charge, emulsifier type, asphalt chemistry. Chip Seal Process and Emulsion Properties - Sprayability The emulsion must be able to be sprayed so that it will form an even fan and laterally distribute on the pavement. Test Indication: Sieve Content Transverse Distribution Test Important Physical Properties: Particle size, contamination, viscosity and viscosity profile, shear thinning, binder content. Chip Seal Process and Emulsion Properties - Thixotropy The emulsion must not run off the pavement and must form an even membrane on which to apply the chips. Test Indication: Binder content, field spray. Shear thinning hysterisis loop. Important Physical Properties: Particle size and distribution, emulsifier type, binder type, binder content. Chip Seal Process and Emulsion Properties - Mobility (Flow) The emulsion must, after spraying, be able to coat the aggregate and pavement surface. Test Indication: Emulsion viscosity. Important Physical Properties: Particle size and distribution, emulsifier type, binder type, binder content. Chip Seal Process and Emulsion Properties - Wetting. The emulsion be able to displace water from the surface of an aggregate and form a chemical bond. Test Indication: Coating, adhesion and stripping tests. Important Physical Properties: Particle size and distribution, emulsifier type, binder type, binder content Chip Seal Process and Emulsion Properties - Breaking. The emulsion must break on and between the aggregate particles slowly enough to allow bond and membrane formation but fast enough to allow traffic quickly. Test Indication: Demulsibility, break tests. Zeta potential. Important Physical Properties: Particle size and distribution, emulsifier type, binder type, binder content. Aggregate type and condition, weather. Chip Seal Process and Emulsion Properties - Curing. The emulsion must be able to coalesce to form an even film and expel water from itself. Test Indication: Water resistance, stripping tests, cure tests.(Vialit). Important Physical Properties: Particle size and distribution, emulsifier type, binder type, binder content. Vialit Physical Properties of Binder Rheological Properties: penetration Viscosity Float Test Ductility Softening Point Elastic Properties ( torsional, elastic) Modulus/ phase angle General CRS-1 is 60% and is made to be stored and used at ambient. CRS-2 (LM) is 65% asphalt and 3% latex and is made to be stored and used at 40 plus C. (AEMA) Emulsions Tests and Storage Base Particle Size Distributions(PSD) Effect of Viscosity Vs Binder Content Effects on Particle size CRS-1 (60%) Effects on Particle size CRS-2 (65% asphalt) 3% latex Effect On Particle Size 70% emulsion 3% Latex Effect Of Storage On Viscosity CRS-1 (60%) Effect Of Storage on Viscosity CRS-2 latex 3% (65%) Effect Of Storage on Viscosity 70% LM 3% Effect Of Storage on Torsional Recovery CRS-2 3% latex (65%) Torsional Recovery 70% 3% latex Effect Of Coarsening on Torsional Recovery d50 v TR (CRS-2 65% with 3% latex) Effect On Morphology Of Storage d50 3um d50 20um Coarsened        Particles 100-150um long Effect on Pen Effect Of Storage on Sieve CRS-1 (60%) Effect Of Storage on Sieve CRS-2 3% latex (65%) Effect on Reheat (store 25C reheat to 40C) Effect of Storage 3% latex LMCRS-2 (All same scale) Fresh CRS-2LM CRS-2LM 7 days 25C CRS-2LM 14 days 25C CRS-2LM 21 days 25C CRS-2LM 28 days CRS-2LM 35 days 25C Effect Of Storage 60% emulsion CRS-1 CRS-1 fresh CRS-1 28 days 25C Other Ways Emulsions Coarsen Pumping Dilution of cationic emulsions CRS type* Very low temperatures Boiling Low emulsifier contents Purpose made low binder content tack coats are usually CSS or will have proportionately higher emulsifier contents based on asphalt Conclusions Storage is a determinant of emulsion stability properties Storage effects dispersion of the polymer in the binder ie its morphology this affects viscoelastic properties Pen is largely unchanged (25C) Back to VSS Technology Papers Library Copyright © 2000 Valley Slurry Seal Co All Rights Reserved.